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Nov 062015
 

 

 Photo: C Schubert/CCAFSWhere to begin a decade-long story like that of the CGIAR Generation Challenge Programme (GCP)? This time-bound programme concluded in 2014 after successfully catalysing the use of advanced plant breeding techniques in the developing world.

Like all good tales, the GCP story had a strong theme: building partnerships in modern crop breeding for food security. It had a strong cast of characters: a palpable community of staff, consultants and partners from all over the world. And it had a formidable structure – two distinct phases split equally over the decade to first discover new plant genetic information and tools, and then to apply what the researchers learnt to breed more tolerant and resilient crops.

In October 2014, at the final General Research Meeting in Thailand, GCP Director Jean-Marcel Ribaut paid tribute to GCP’s cast and crew: “To all the people involved in GCP over the last 12 years, you are the real asset of the Programme,” he told them.

“In essence, our work has been all about partnerships and networking, bringing together players in crop research who may otherwise never have worked together,” says Jean-Marcel. “GCP’s impact is not easy to evaluate but it’s extremely important for effective research into the future. We demonstrated proofs of concept that can be scaled up for powerful results.”

A significant aspect of GCP’s legacy is the abundance of collaborations it forged and fostered between international researchers. A typical GCP project brought together public and private partners from both developing and developed nations and from CGIAR Centres. In all, more than 200 partners collaborated on GCP projects.

Photo: GCP

Just some of the extended GCP family assembled for the Programme’s final General Research Meeting in 2014.

The idea that the ‘community would pave the way towards success’ was always a key foundation of GCP, according to Dave Hoisington, who was involved with GCP from its conception and was latterly Chair of GCP’s Consortium Committee. “We designed GCP to provide opportunities for researchers to work together,” says Dave. He is a senior research scientist and program director at the University of Georgia, and was formerly Director of Research at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and Director of the Genetic Resources Program and of the Applied Biotechnology Center at the International Maize and Wheat Improvement Center (CIMMYT).

“GCP was the mechanism that would help us to complete our mission – to tap into the rich genetic diversity of crops and package it so that breeding programme researchers could integrate it into their operations,” says Dave.

Photo: ICRISAT

A little girl tucks into sorghum porridge in Mali.

The dawn of a new generation

Food security in the developing world continues to be one of the greatest global challenges of our time. One in nine people worldwide – or more than 820 million people – go hungry every day.

Although this figure is currently diminishing, a changing global climate is making food production more challenging for farmers. Farmers need higher yielding crops that can grow with less water, tolerate higher temperatures and poorer soils, and resist pests and diseases.

The turn of the millennium saw rapid technological developments emerging in international molecular plant science. New tools and approaches were developed that enabled plant scientists, particularly in the developing world, to make use of genetic diversity in plants that was previously largely inaccessible to them. These tools had the potential to increase plant breeders’ capacity to rapidly develop crop varieties able to tolerate extreme environments and yield more in farmers’ fields.

Photo: J van de Gevel/Bioversity International

Wheat varieties in a field trial.

Dave was one scientist who early on recognised the significance and potential of this new dawn in plant science. In 2002, while working at CIMMYT, he teamed up with the Center’s then Director General, Masa Iwanaga, and its then Executive Officer for Research, Peter Ninnes – another long-term member of the GCP family who at the other end of the Programme’s lifespan became its Transition Manager. Together with a Task Force of other collaborators from CIMMYT, the International Rice Research Institute (IRRI) and IPGRI (now Bioversity International), they drafted and presented a joint proposal to form a CGIAR Challenge Programme – and so GCP was conceived.

The five CGIAR Challenge Programmes were the early precursors of the current CGIAR Research Programs. They introduced a new model for collaboration among CGIAR Research Centers and with external institutes, particularly national breeding programmes in developing countries.

A programme where the spirit is palpable

Photo: N Palmer/CIAT

Failed harvest: this Ghanaian farmer’s maize ears are undersized and poorly developed due to drought.

From the beginning, GCP had collaboration and capacity building at its heart. As encapsulated in its tagline, “partnerships in modern crop breeding for food security,” GCP’s aim was to bring breeders together and give them the tools to more effectively breed crops for the benefit of the resource-poor farmers and their families, particularly in marginal environments.

GCP’s primary focus on was on drought tolerance and breeding for drought-prone farming systems, since this is the biggest threat to food security worldwide – and droughts are already becoming more frequent and severe with climate change. However, the Programme made major advances in breeding for resilience to other major stresses in a number of different crops, including acid soils and important pests and diseases. It also sought improved yields and nutritional quality.

The model for the Programme was that it would work by contracting partner institutes to conduct research, initially through competitive projects and later through commissioning. These partnerships would ensure that GCP’s overall objectives were met. For Dave, GCP set the groundwork for modern plant breeding.

“GCP demonstrated that you can tap into genetic resources and that they can be valuable and can have significant impacts on breeding programmes,” he says.

“I think GCP started to guide the process. Without GCP, the adoption, testing and use of molecular technologies would probably have been delayed.”

Photo: Meena Kadri/Flickr (Creative Commons)

Harvesting wheat in India.

Masa Iwanaga, who is now President of the Japan International Research Center for Agricultural Sciences (JIRCAS), says that the key to the proposal and ultimate success of GCP was the focus on building connections between partners worldwide. “By providing the opportunity for researchers from developed countries to partner with researchers in developing countries, it helped enhance the capacity of national programmes in developing countries to use advanced technology for crop improvement.”

While not all partnerships were fruitful, Jean-Marcel has observed that those participants who invested in partnerships and built trust, understanding and communication produced some of the most successful results. “We created this amazing chain of people, stretching from the labs to the fields,” said Jean-Marcel, discussing the Programme in a 2012 interview.

“Perhaps the best way I can describe it is as a ‘GCP spirit’ created by the researchers we worked with.

“The Programme’s environment is friendly, open to sharing and is marked by a strong sense of community and belonging. The GCP spirit is visible and palpable: you can recognise people working with us have a spirit that is typical of the Programme.”

Exploring gene banks to uncover genetic wealth

GCP started operations in 2004 and was designed in two five-year phases, 2004–2008 and 2009–2013. 2014 was a transition year for orderly closure.

Phase I focussed on upstream research to generate knowledge and tools for modern plant breeding. It mainly consisted of exploration and discovery projects, funded on a competitive basis, pursuing the most promising molecular research and high-potential partnerships.

“GCP’s first task was to go in and identify the genetic wealth held within the CGIAR gene banks,” says Dave Hoisington.

Photo: IITA

Gene bank samples give a small snapshot of cowpea diversity.

CGIAR’s gene banks were originally conceived purely for conservation, but breeders increasingly recognised the tremendous value of studying and utilising these collections. Over the years they were able to use gene banks as a valuable source of new breeding material, but were hampered by having to choose seeds almost blindly, with limited knowledge of what useful traits they might contain.

“We realised we could use molecular tools to help scan the genomes and discover genes in crops of interest and related species,” says Dave. “The genes we were most interested in were ones that helped increase yield in harsh environments, particularly under drought.”

By studying the genomes of wild varieties of wheat, for example, researchers found genes that increase wheat’s tolerance of water stress.

Photo: International Potato Center (CIP)

Sweetpotato diversity.

GCP-supported projects analysed naturally occurring genetic diversity to produce cloned genes, informative markers and reference sets for 21 important food crops. ‘Reference sets’, or ‘reference collections’ reduce search time for researchers: they are representative selections of a few hundred plant samples (‘accessions’) that encapsulate each crop’s genetic diversity, narrowed down from the many thousands of gene bank accessions available. The resources developed through GCP have already proved enormously valuable, and will continue to benefit researchers for years to come.

For example, researchers developed 52 new molecular (DNA) markers for sweetpotato to enable marker-assisted selection for resistance to sweet potato virus disease (SPVD). For lentils, a reference set of about 150 accessions was produced, a distillation down to 15 percent of the global collection studied. And for barley, 90 percent of all the different characteristics of barley were captured within 300 representative plant lines.

Photo: ICARDA

Harvesting barley in Ethiopia.

The leader of GCP’s barley research, Michael Baum, who directs the Biodiversity and Integrated Gene Management Program at the International Center for Agricultural Research in the Dry Areas (ICARDA), says the reference set is a particular boon for a researcher new to barley.

“By looking at 300 lines, they see the diversity of 3,000 lines without any duplication,” says Michael. “This is much better and quicker for a plant breeder.”

Similarly, the lentil reference set serves as a common resource for ICARDA’s team of lentil breeders, facilitating efficient collaboration, according to Aladdin Hamweih of ICARDA, who was charged with developing the lentil collection for GCP.

“These materials can be accessed to achieve farming goals – to produce tough plants suitable for local environments. In doing this, we give farmers a greater likelihood of success, which ultimately leads to improving food security for the wider population,” Aladdin says.

An important aspect of the efforts within Phase I was GCP’s emphasis on developing genomic resources such as reference sets for historically under-resourced crops that had received relatively little investment in genetic research. These made up most of GCP’s target crops, and included: bananas and plantains; cassava; coconuts; common beans; cowpeas; chickpeas; groundnuts; lentils; finger, foxtail and pearl millets; pigeonpeas; potatoes; sorghum; sweetpotatoes and yams.

Although not all of these historically under-resourced crops continued to receive research funding into Phase II, the outcomes from Phase I provided valuable genetic resources and a solid basis for the ongoing use of modern, molecular-breeding techniques. Indeed, thanks to their GCP boost, some of these previously neglected species have become model crops for genetic and genomic research – even overtaking superstar crops such as wheat, whose highly complex genome hampers scientists’ progress.

Photo: N Palmer/CIAT

Banana harvest for sale in Rwanda.

A need to focus and deliver products

“Phase I provided plenty of opportunity for researchers to tap into genetic diversity,” says Jean-Marcel. “We opened the door for a lot of different topics which helped us to identify projects worth pursuing further, as well as identifying productive partnerships. But at the same time, we were losing focus by spreading ourselves too thinly across so many crops.”

This notion was confirmed by the authors of an external review conducted in 2008, commissioned by CGIAR. This recommended consolidating GCP’s research in order to optimise efficiency and increase outputs during GCP’s second phase, while also enhancing potential for longer term impact.

Transparency and a willingness to respond and adapt were always core GCP values. The Programme embraced external review throughout its lifetime, and was able to make dynamic changes in direction as the best ways to achieve impact emerged. Markus Palenberg, Managing Director of the Institute for Development Strategy in Germany, was a member of the 2008 evaluation panel.

“One major recommendation from the evaluation was to focus on crops and tools which would provide the greatest impact in terms of food security,” recounts Markus, who later joined GCP’s Executive Board. “This resulted in the Programme refocusing its research on only nine core crops.” These were cassava, beans, chickpeas, cowpeas, groundnuts, maize, rice, sorghum and wheat.

Photo: Mann/ILRI

Hard work: harvesting groundnut in Malawi.

GCP’s decision-making process on how to focus its Phase II efforts was partly guided by research the Programme had commissioned, documented in its Pathways to impact brief No 1: Where in the world do we start? This took global data on the number of stunted – i.e., severely malnourished – children, as a truer indicator of poverty than a monetary definition, and overlaid it on maps showing where drought was most likely to occur and have a serious impact on crop productivity. This combination of poverty and vulnerable harvests was used to determine the farming systems where GCP might have most impact.

The Programme also attempted to maintain a balance between types of crops, including each of the following categories: cereals (maize, rice, sorghum, wheat), legumes (beans, chickpeas, cowpeas, groundnuts), and roots and tubers (cassava).

The crops were organised into six crop- specific Research Initiatives (RIs) – legumes were consolidated into one – plus a seventh, Comparative Genomics, which focused on exploiting genetic similarities among rice, maize and sorghum to find and deploy sources of tolerance to acid soils.

Photo: IRRI

Child eating rice.

The research under the RIs built on GCP’s achievements in Phase I, moving from exploration to application. The change in focus was underpinned by the planned shift from competitive to commissioned projects, allowing the Programme to continue to support its strongest partnerships and research strands.

“The RIs focused on promoting the use of modern integrated breeding approaches, using both conventional and molecular breeding methods, to improve each crop through a series of specific projects undertaken in more than 30 countries,” says Jean-Marcel. “More importantly, the RIs were focused on creating new genetic material and varieties of plants that would ultimately benefit farmers.”

Such products released on the ground included new varieties of:

  • cassava resistant to several diseases, tolerant to drought, nutritionally enhanced to provide high levels of vitamin A, and with higher starch content for high-quality cassava flour and starch processing
  • chickpea tolerant to drought and able to thrive in semi-arid conditions, already providing improved food and income security for smallholder African farmers  – yields have doubled in Ethiopia – and set to help them supply growing demand for the legume in India
  • maize with higher yields, tolerant to high levels of aluminium in acid soils, resistant to disease, adapted to local conditions in Africa – and with improved phosphorus efficiency in the pipeline
  • rice with tolerance to drought and low levels of phosphorus in acid soils, disease resistance, high grain quality, and tolerance to soil salinity – with improved aluminium tolerance on the way too
Photo: CSISA

Harvesting rice in India.

Over the coming years, many more varieties developed through GCP projects are expected to be available to farmers, as CGIAR Research Centres and national programmes continue their work.

These will include varieties of:

  • common bean resistant to disease and tolerant to drought and heat, with higher yields in drier conditions – due for release in several African countries from 2015 onwards
  • cowpea resistant to diseases and insect pests, with higher yields, and able to tolerate worsening drought – set for release in several countries from 2015, to secure and improve harvests in sub-Saharan Africa
  • groundnut tolerant to drought and resistant to pests, diseases, and the fungi that cause aflatoxin contamination, securing harvests and raising incomes in some of the poorest regions of Africa
  • maize tolerant to drought and adapted to local conditions and tastes in Asia
  • sorghum that is even more robust and adapted to increasing drought in the arid areas of sub-Saharan Africa – plus sorghum varieties able to tolerate high aluminium levels in acid soils, set for imminent release
  • wheat with heat and drought tolerance – as well as improved yield and grain quality – for India and China, the two largest wheat producers in the world
Photo: N Palmer/CIAT

Groundnut harvest, Ghana.

Giving a voice to all the cast and crew

The 2008 external review also recommended slight changes in governance. It suggested GCP receive more guidance from two proposed panels: a Consortium Committee and an independent Executive Board.

Dave Hoisington, who chaired the Committee from 2010, succeeding the inaugural Chair Yves Savidan, explains: “GCP was not a research programme run by a single institute, but a consortium of 18 institutes. By having a committee of the key players in research as well as an independent board comprising people who had no conflict of interest with the Programme, we were able to make sure both the ‘players’ and ‘referees’ were given a voice.”

Jean-Marcel says providing this voice to everyone involved was an important facet of effective management. “Given that GCP was built on its people and partnerships, it was important that we restructured our governance to provide everyone with a representative to voice their thoughts on the Programme. We have always tried to be very transparent.”

The seven-member Executive Board was instated in June 2008 to provide oversight of the scientific strategy of the Programme. Board members had a wide variety of skills and backgrounds, with expertise ranging across molecular biology, development assistance, socioeconomics, academia, finance, governance and change management.

Andrew Bennett, who followed inaugural Chair Calvin Qualset into the role in 2009, has more than 45 years of experience in international development and disaster management and has worked in development programmes in Africa, Asia, Latin America, the Pacific and the Caribbean.

“The Executive Board’s first role was to provide advice and to help the Consortium Committee and management refocus the Programme,” says Andrew.

Photo: IRRI

Rice seed diversity.

‘Advice’ and ‘helping’ are not usually words associated with how a Board works but, like so much of GCP’s ‘family’, this was not a typical board. Because GCP was hosted by CIMMYT, the Board did not have to deal with any policy issues; that was the responsibility of the Consortium Committee. As Andrew explains, “Our role was to advise on and help with decision-making and implementation, which was great as we were able to focus on the Programme’s science and people.”

Andrew has been impressed by what GCP has been able to achieve in its relatively short lifespan in comparison with other research programmes. “I think this programme has demonstrated that a relatively modest amount of money used intelligently can move with the times and help identify areas of potential benefit.”

Developing capacity and leadership in Africa

As GCP’s focus shifted from exploration and discovery to application and impact between Phases I and II, project leadership shifted too. More and more projects were being led by developing-country partners.

Harold Roy-Macauley, GCP Board member and Executive Director of the West and Central African Council for Agricultural Research and Development (WECARD), advised GCP about how to develop capacity, community and leadership among African partners so that products would reach farmers.

“The objective was to make sure that we were influencing development within local research communities,” says Harold. “GCP has played a very important role in creating synergies between the different institutions in Africa. Bringing the right people together, who are working on similar problems, and providing them with the opportunity to lead, has brought about change in the way researchers are doing research.”

In the early years of the Programme, only about 25 percent of the research budget was allocated to research institutes in developing countries; this figure was more than 50 percent in 2012 and 2013.

Jean-Marcel echoes Harold’s comments: “To make a difference in rural development – to truly contribute to improved food security through crop improvement and incomes for poor farmers – we knew that building capacity had to be a cornerstone of our strategy,” he says. Throughout its 10 years, GCP invested 15 percent of its resources in developing capacity.

“Providing this capacity has enabled people, research teams and institutes to grow, thrive and stand on their own, and this is deeply gratifying. It is very rewarding to see people from developing countries growing and becoming leaders,” says Jean-Marcel.

“For me, seeing developing-country partners come to the fore and take the reins of project leadership was one of the major outcomes of the Programme. Providing them with the opportunity, along with the appropriate capacity, allowed them to build their self-confidence. Now, many have become leaders of other transnational projects.”

Emmanuel Okogbenin and Chiedozie Egesi, two plant breeders at Nigeria’s National Root Crops Research Institute (NRCRI), are notable examples. They are leading an innovative new project using marker-assisted breeding techniques they learnt during GCP projects to develop higher-yielding, stress-tolerant cassava varieties. For this project, they are partnering with the Bill & Melinda Gates Foundation, Cornell University in the USA, the International Institute of Tropical Agriculture (IITA) and Uganda’s National Crops Resources Research Institute (NaCRRI).

Chiedozie says this would not have been possible without GCP helping African researchers to build their profiles. “GCP helped us to build an image for ourselves in Nigeria and in Africa,” he says, “and this created a confidence in other global actors, who, on seeing our ability to deliver results, are choosing to invest in us.”

Photo: IITA

Nigerian cassava farmer.

A ‘sweet and sour’ sunset

Photo: Daryl Marquardt/Flickr (Creative Commons)

Maize at sunset.

Jean-Marcel defined GCP’s final General Research Meeting in Thailand in 2014 as a ‘sweet-and-sour experience’.

Summing up the meeting, Jean-Marcel said, “It was sour in terms of GCP’s sunset, and sweet in terms of seeing you all here, sharing your stories and continuing your conversations with your partners and communities.”

From the outset, GCP was set up as a time-bound programme, which gave partners specific time limits and goals, and the motivation to deliver products. However, much of the research begun during GCP projects will take longer than 10 years to come to full fruition, so it was important for GCP to ensure that the research effort could be sustained and would continue to deliver farmer-focused outcomes.

During the final two years of the Programme, the Executive Board, Consortium Committee and Management Team played a large role in ensuring this sustainability through a thoroughly planned handover.

“We knew we weren’t going to be around forever, so we had a plan from early on to hand over the managerial reins to other institutes, including CGIAR Research Programs,” says Jean-Marcel.

One of the largest challenges was to ensure the continuity and future success of the Integrated Breeding Platform (IBP). IBP is a web-based, one-stop shop for information, tools and related services to support crop breeders in designing and carrying out integrated breeding projects, including both conventional and marker-assisted breeding methods.

While there are already a number of other analytical and data management breeding systems on the market, IBP combines all the tools that a breeder needs to carry out their day-to-day logistics, plan crosses and trials, manage and analyse data, and analyse and refine breeding decisions. IBP is also unique in that it is geared towards supporting breeders in developing countries – although it is already proving valuable to a wide range of breeding teams across the world. The Platform is set up to grow and improve as innovative ideas emerge, as users can develop and share their own tools.

Beyond the communities and relationships fostered by GCP community, Jean-Marcel sees IBP as the most important legacy of the Programme. “I think that the impact of IBP will be huge – so much larger than GCP. It will really have impact on how people do their business, and adopt best practice.”

While the sun is setting on GCP, it is rising for IBP, which is in an exciting phases as it grows and seeks long-term financial stability. The Platform is now independent, with its headquarters hosted at CIMMYT, and has established a number of regional hubs to provide localised support and training around the world, with more to follow.

It is envisaged that IBP will be invaluable to researchers in both developing and developed countries for many years to come, helping them to get farmers the crop varieties they need more efficiently. IBP is also helping to sustain some of the networks that GCP built and nurtured, as it is hosting the crop-specific Communities of Practice established by GCP.

2014 may be the end of GCP’s story but its legacy will live on. It will endure, of course, in the Programme’s scientific achievements – for many crops, genetic research and the effective use of genetic diversity in molecular breeding are just beginning, and GCP has helped to kick-start a long and productive scientific journey – and in the valuable tools brought together in IBP. And most of all, GCP’s character, communities and spirit will live on in all those who formed part of the GCP family.

For Chiedozie Egesi, the partnerships fostered by GCP have changed the way he does research: “We now have a network of cassava breeders that you can count on and relate with in different countries. This has really widened our horizons.

Fellow cassava breeder Elizabeth Parkes of Ghana agrees that GCP’s impact will be a lasting one: “All the agricultural research institutes and individual scientists who came into contact with GCP have been fundamentally transformed.”

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Photo: E Hermanowicz/Bioversity International

Cowpea seeds dried in their pods.

Oct 262015
 

 

Photo: HK Tang/Flickr (Creative Commons)

An Indian patchwork of rice and maize fields.

“Once you’ve cloned a major gene in one crop, it is possible to find a counterpart gene that has the same function in another crop, and this is easier than finding useful genes from scratch” explains Leon Kochian, Professor in Plant Biology and Crop and Soil Sciences at Cornell University, USA, and Director of the Robert W Holley Center for Agriculture and Health, United States Department of Agriculture – Agricultural Research Service.

Leon was the Product Delivery Coordinator for the Comparative Genomics Research Initiative of the CGIAR Generation Challenge Programme (GCP). The Programme set out in 2004 to advance plant genetics in a bid to provide sustainable food-security solutions.

Between 2004 and 2014, GCP invested in projects to clone two genes and deploy them in elite local varieties. The first gene, SbMATE, encodes aluminium tolerance traits in sorghum; the work was a collaborative effort led by the Brazilian Corporation of Agricultural Research (EMBRAPA) and Cornell University, and gave rise to locally-adapted sorghum varieties released in South America and Africa. The second gene, PSTOL1, produces traits that improve phosphorus uptake in rice. This research was a collaboration between the Japan International Research Center for Agricultural Sciences (JIRCAS) and the International Rice Research Institute (IRRI). PSTOL1 has now been extensively deployed in Asian rice varieties.

Aluminium toxicity and low phosphorus levels in acid soils are major factors that hinder cereal productivity worldwide, particularly in sub-Saharan Africa, South America and Southeast Asia. Globally, acid soils are outranked only by drought when it comes to stresses that threaten food security.

Tolerance to high levels of aluminium and low phosphorus is conferred by major genes, which lend themselves to cloning. Major genes are genes that by themselves have a significant and evident effect in producing a particular trait; it’s therefore easier to find and deploy a major gene associated with a desired trait than having to find and clone several minor genes.

Photo: S Kilungu/CCAFS

Harvesting sorghum in Kenya.

Cloning major genes instrumental in hunt for resilient varieties

Locating a single gene within a plant’s DNA is like looking for a needle in a haystack. Instead of searching for a gene at random, geneticists need a plan for finding it.

The first step is to conduct prolonged phenotyping – that is, measuring and recording of plants’ observable characteristics in the field. By coupling and comparing this knowledge with genetic sequencing data, scientists can identify and locate quantitative trait loci (QTLs) – discrete genetic regions that contain genes associated with a desired trait, in this instance tolerance to aluminium or improved phosphorus uptake. They then dissect the QTL to single out the gene responsible for the desired trait. In the case of sorghum, researchers had identified the aluminium tolerance locus AltSB, and were looking for the gene responsible.

Once the gene has been identified, the next step is to clone it – that is, make copies of the stretch of DNA that makes up the gene. Geneticists need millions of copies of the same gene for their research: to gain information about the nucleotide sequence of the gene, create molecular markers to help identify the presence of the gene in plants and help compare versions of the gene from different species, and understand the mechanisms it controls and ways it interacts with other genes.

Photo: ICRISAT

Drying the sorghum harvest in India.

Sorghum was one of the simpler crops to work with, according to Claudia Guimarães.

“Sorghum has a smaller genome… with clear observable traits, which are often controlled by one major gene,” she says.

The first breakthrough was the identification and cloning of SbMATE, the aluminium tolerance gene in sorghum behind the AltSB locus. The next was finding a diagnostic marker for the gene so that it could be used in breeding.

Marking genes to quickly scan plants for desired traits

Photo: IRRI

Harvesting rice in The Philippines.

Once a desired gene is identified, a specific molecular marker must be found for it. This is a variation in the plant’s DNA, associated with a gene of interest, that scientists can use to flag up the gene’s presence. We can compare this process to using a text highlighter in a book, where the words represent the genes making up a genome. Each marker is like a coloured highlighter, marking sentences (genomic regions) containing particular keywords (genes) and making them easier to find.

In molecular breeding, scientists can use markers to quickly scan hundreds or thousands of DNA samples of breeding materials for a gene, or genes, that they want to incorporate into new plant varieties. This enables them to select parents for crosses more efficiently, and easily see which of the next generation have inherited the gene. This marker-assisted breeding method can save significant time and money in getting new varieties out into farmers’ fields.

Leon, who was also the Principal Investigator for various GCP-funded research projects, says that the cloning of SbMATE helped advance sorghum as a model for the further exploration of aluminium tolerance and the discovery of new molecular solutions for improving crop yields.

“This research also has environmental implications for badly needed increases in food production on marginal soils in developing countries,” says Leon. “For example, if we can increase food production on existing lands, it could limit agriculture’s encroachment into other areas.”

Photo: IRRI

Rice field trials in Tanzania.

Aluminium toxicity is the result of aluminum becoming more available to plants when the soil pH is lower, and affects 38 percent of farmland in Southeast Asia, 31 percent in South America and 20 percent in East Asia, sub-Saharan Africa and North America. Meanwhile phosphorus, the second most important inorganic plant nutrient after nitrogen, becomes less available to plants in acid soils because it binds with aluminium and iron oxides. Almost half of the ricelands across the globe are currently phosphorus deficient. The research therefore has the potential for significant impact across the world.

The GCP-funded scientists used markers to search rice and maize for genes equivalent to sorghum’s SbMATE. In maize they successfully identified a similar gene, ZmMATE1, which is now being validated in Brazil, Kenya and Mali. In rice the search continues, but will become easier now that markers for ZmMATE1 have been developed.

Similarly, having validated, cloned and developed markers for PSTOL1 gene in rice, researchers at IRRI and JIRCAS then worked with researchers at EMBRAPA and Cornell University to use PSTOL1 markers to search for comparable genes in sorghum and maize. In both crops, genes similar to PSTOL1 have been identified and shown to improve grain yields under low-phosphorus soil conditions, albeit through different mechanisms.

The GCP-funded discoveries are already being used in marker-assisted selection in national breeding programmes in Brazil, Kenya, Niger, Indonesia, Japan, The Philippines and USA in sorghum, maize and rice. They have led to the release of new, aluminium-tolerant sorghum varieties in Brazil, with more currently being developed, along with phosphorus-efficient rice varieties.

Photo: S Kilungu/CCAFS

Showing off freshly harvested sorghum in Kenya.

Cloning a worthwhile investment

Gene cloning was a relatively small cost in GCP’s research budget – about five percent (approximately USD 7 million) of a total research budget of USD 150 million spread over 10 years.

The gene-cloning component nonetheless yielded important genes for aluminium tolerance and phosphorus-uptake efficiency, within and across genomes. The molecular markers that have been developed are helping plant breeders across the world produce improved crop varieties.

Jean-Marcel Ribaut, Director of GCP, concludes: “The new markers developed for major genes in rice, sorghum and maize will have a significant impact on plant-breeding efficiency in developing countries.

“Breeders will be able to identify aluminium-tolerance and phosphorus-efficiency traits quicker, which, in time, will enable them to develop new varieties that will survive and thrive in the acid soils that make up more than half of the world’s arable soils.”

More links

Photo: CSISA

A rice farmer in Bihar, India.

Oct 122015
 

 

Photo: One Acre Fund/Flickr (Creative Commons)

A Kenyan farmer harvesting her maize.

“The map of Kenya’s maize-growing regions mirrors the map of the nation’s acid soils.”

So says Dickson Ligeyo, senior research officer at the Kenya Agricultural and Livestock Research Organisation (KALRO; formerly the Kenya Agricultural Research Institute, or KARI), who believes this paints a sombre picture for his country’s maize farmers.

Maize is a staple crop for Kenyans, with 90 percent of the population depending on it for food. However, acid soils cause yield losses of 17–50 percent across the nation.

Soil acidity is a major environmental and economic concern in many more countries around the world. The availability of nutrients in soil is affected by pH, so acid conditions make it harder for plants to get a balanced diet. High acidity causes two major problems: perilously low levels of phosphorus and toxically high levels of aluminium. Aluminium toxicity affects 38 percent of farmland in Southeast Asia, 31 percent in Latin America and 20 percent in East Asia, sub-Saharan Africa and North America.

Aluminium toxicity in soil comes close to rivalling drought as a food-security threat in critical tropical food-producing regions. By damaging roots, acid soils deprive plants of the nutrients and water they need to grow – a particularly bitter effect when water is scarce.

Maize, meanwhile, is one of the most economically important food crops worldwide. It is grown in virtually every country in the world, and it is a staple food for more than 1.2 billion people in developing countries across sub-Saharan Africa and Latin America. In many cultures it is consumed primarily as porridge: polenta in Italy; angu in Brazil; and isitshwala, nshima, pap, posho,sadza or ugali in Africa.

Photo: Allison Mickel/Flickr (Creative Commons)

Ugali, a stiff maize porridge that is a staple dish across East Africa, being prepared in Tanzania.

Maize is also a staple food for animals reared for meat, eggs and dairy products. Around 60 percent of global maize production is used for animal feed.

The world demand for maize is increasing at the same time as global populations burgeon and climate changes. Therefore, improving the ability of maize to withstand acid soils and produce higher yields with less reliable rainfall is paramount. This is why the CGIAR Generation Challenge Programme (GCP) invested almost USD 12.5 million into maize research between 2004 and 2014.

GCP’s goal was to facilitate the use of genetic diversity and advanced plant science to improve food security in developing countries through the breeding of ‘super’ crops – including maize – able to tolerate drought and poor soils and resist diseases.

 By weight, more maize is produced each year than any other grain: global production is more than 850 million tonnes. Maize production is increasing at twice the annual rate of rice and three times that of wheat. In 2020, demand for maize in developing countries alone is expected to exceed 500 million tonnes and will surpass the demand for both rice and wheat.  This projected rapid increase in demand is mainly because maize is the grain of choice to feed animals being reared for meet – but it is placing strain on the supply of maize for poor human consumers. Demand for maize as feed for poultry and pigs is growing, particularly in East and Southeast Asia, as an ever-increasing number of people in Asia consume meat. In some areas of Asia, maize is already displacing sorghum and rice. Acreage allocated to maize production in South and Southeast Asia has been expanding by 2.2 percent annually since 2001. In its processed form, maize is also used for biofuel (ethanol), and the starch and sugars from maize end up in beer, ice cream, syrup, shoe polish, glue, fireworks, ink, batteries, mustard, cosmetics, aspirin and paint.

Researchers take on the double whammy of acid soils and drought

Part of successfully breeding higher-yielding drought-tolerant maize varieties involves improving plant genetics for acid soils. In these soils, aluminium toxicity inhibits root growth, reducing the amount of water and nutrients that the plant can absorb and compounding the effects of drought.

Improving plant root development for aluminium tolerance and phosphorous efficiency can therefore have the positive side effect of higher plant yield when water is limited.

Photo: A Wangalachi/CIMMYT

A farmer in Tanzania shows the effects of drought on her maize crop. The maize ears are undersized with few grains.

Although plant breeders have exploited the considerable variation in aluminium tolerance between different maize varieties for many years, aluminium toxicity has been a significant but poorly understood component of plant genetics. It is a particularly complex trait in maize that involves multiple genes and physiological mechanisms.

The solution is to take stock of what maize germplasm is available worldwide, characterise it, clone the sought-after genes and implement new breeding methods to increase diversity and genetic stocks.

Scientists join hands to unravel maize complexity

Scientists from the International Maize and Wheat Improvement Center (CIMMYT) and the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) got their heads together between 2005 and 2008 to itemise what maize stocks were available.

Marilyn Warburton, then a molecular geneticist at CIMMYT, led this GCP-funded project. Her goal was to discover how all the genetic diversity in maize gene-bank collections around the globe might be used for practical plant improvement. She first gathered samples from gene banks all over the world, including those of CIMMYT and the International Institute of Tropical Agriculture (IITA). Scientists from developing country research centres in China, India, Indonesia, Kenya, Nigeria, Thailand and Vietnam also contributed by supplying DNA from their local varieties.

Photo: X Fonseca/CIMMYT

Maize diversity.

Researchers then used molecular markers and a bulk fingerprinting method – which Marilyn was instrumental in developing – for three purposes: to characterise the structure of maize populations, to better understand how maize migrated across the world, and to complete the global picture of maize biodiversity. Scientists were also using markers to search for new genes associated with desirable traits.

Allen Oppong, a maize pathologist and breeder from Ghana’s Crops Research Institute (CRI), of the Council for Scientific and Industrial Research, was supported by GCP from 2007 to 2010 to characterise Ghana’s maize germplasm. Trained in using the fingerprinting technique, Allen was able to identify distinctly different maize germplasm in the north of Ghana (with its dry savanna landscape) and in the south (with its high rainfall). He also identified mixed germplasm, which he says demonstrates that plant germplasm often finds its way to places where it is not suitable for optimal yield and productivity. Maize yields across the country are low.

Stocktaking a world’s worth of maize for GCP was a challenge, but not the only one, according to Marilyn. “In the first year it was hard to see how all the different partners would work together. Data analysis and storage was the hardest; everyone seemed to have their own idea about how the data could be stored, accessed and analysed best.

“The science was also evolving, even as we were working, so you could choose one way to sequence or genotype your data, and before you were even done with the project, a better way would be available,” she recalls.

Photo: N Palmer/CIAT

Maize ears drying in Ghana.

Comparing genes: sorghum gene paves way for maize aluminium tolerance

In parallel to Marilyn’s work, scientists at the Brazilian Corporation of Agricultural Research (EMBRAPA) had already been advancing research on plant genetics for acid soils and the effects of aluminium toxicity on sorghum – spurred on by the fact that almost 70 percent of Brazil’s arable land is made up of acid soils.

What was of particular interest to GCP in 2004 was that the Brazilians, together with researchers at Cornell University in the USA, had recently mapped and identified the major sorghum aluminium tolerance locus AltSB, and were working on isolating the major gene within it with a view to cloning it. Major genes were known to control aluminium tolerance in sorghum, wheat and barley and produce good yields in soils that had high levels of aluminium. The gene had also been found in rape and rye.

GCP embraced the opportunity to fund more of this work with a view to speeding up the development of maize – as well as sorghum and rice – germplasm that can withstand the double whammy of acid soils and drought.

Photo: L Kochian

Maize trials in the field at EMBRAPA. The maize plants on the left are aluminium-tolerant and so able to withstand acid soils, while those on the right are not.

Leon Kochian, Director of the Robert W Holley Center for Agriculture and Health, United States Department of Agriculture – Agricultural Research Service and Professor at Cornell University, was a Principal Investigator for various GCP research projects investigating how to improve grain yields of crops grown in acid soils. “GCP was interested in our work because we were working with such critical crops,” he says.

“The idea was to use discoveries made in the first half of the GCP’s 10-year programme – use comparative genomics to look into genes of rice and maize to see if we can see relations in those genes – and once you’ve cloned a gene, it is easier to find a gene that can work for other crops.”

The intensity of GCP-supported maize research shifted up a gear in 2007, after the team led by Jurandir Magalhães, research scientist in molecular genetics and genomics of maize and sorghum at EMBRAPA, used positional cloning to identify the major sorghum aluminium tolerance gene SbMATE responsible for the AltSB aluminium tolerance locus. The team comprised researchers from EMBRAPA, Cornell, the Japan International Research Center for Agricultural Sciences (JIRCAS) and Moi University in Kenya.

By combing the maize genome searching for a similar gene to sorghum’s SbMATE, Jurandir’s EMBRAPA colleague Claudia Guimarães and a team of GCP-supported scientists discovered the maize aluminium tolerance gene ZmMATE1. High expression of this gene, first observed in maize lines with three copies of ZmMATE1, has been shown to increase aluminium tolerance.  ZmMATE1 improves grain yields in acid soil by up to one tonne per hectare when introgressed in an aluminium-sensitive line.

Photos: 1 – V Alves ; 2 – F Mendes; both edited by C Guimarães

The genetic region, or locus, containing the ZmMATE1 aluminium tolerance gene is known as qALT6. Photo 1 shows a rhyzobox containing two layers of soil: a corrected top-soil and lower soils with 15 percent aluminium saturation. On the right, near-isogenic lines (NILs) introgressed with qALT6 show deeper roots and longer secondary roots in the acidic lower soil, whereas on the left the maize line without qALT6, L53, shows roots mainly confined to the corrected top soil. Photo 2 shows maize ears from lines without qALT6 (above) and with qALT6 (below); the lines with qALT6 maintain their size and quality even under high aluminium levels of 40 percent aluminium saturation.

The outcomes of these GCP-supported research projects provided the basic materials, such as molecular markers and donor sources of the positive alleles, for molecular-breeding programmes focusing on improving maize production and stability on acid soils in Latin America, Africa and other developing regions.

Kenya deploys powerful maize genes

One of those researchers crucial to achieving impact in GCP’s work in maize was Samuel (Sam) Gudu of Moi University, Kenya. From 2010 he was the Principal Investigator for GCP’s project on using marker-assisted backcrossing (MABC) to improve aluminium tolerance and phosphorous efficiency in maize in Kenya. This project combined molecular and conventional breeding approaches to speed up the development of maize varieties adapted to the acid soils of Africa, and was closely connected to the other GCP comparative genomics projects in maize and sorghum.

MABC is a type of marker-assisted selection (see box), which Sam’s team – including Dickson Ligeyo of KALRO – used to combine new molecular materials developed through GCP with Kenyan varieties. They have thus been able to significantly advance the breeding of maize varieties suitable for soils in Kenya and other African countries.

Marker-assisted selection helps breeders like Sam Gudu more quickly develop plants that have desirable genes. When two plants are sexually crossed, both positive and negative traits are inherited. The ongoing process of selecting plants with more desirable traits and crossing them with other plants to transfer and combine such traits takes many years using conventional breeding techniques, as each generation of plants must be grown to maturity and phenotyped – that is, the observable characteristics of the plants must be measured to determine which plants might contain genes for valuable traits.   By using molecular markers that are known to be linked to useful genes such as ZmMATE1, breeders can easily test plant materials to see whether or not these genes are present. This helps them to select the best parent plants to use in their crosses, and accurately identify which of the progeny have inherited the gene or genes in question without having to grow them all to maturity. Marker-assisted selection therefore reduces the number of years it takes to breed plant varieties with desired traits.

Maize and Comparative Genomics were two of seven Research Initiatives (RIs) where GCP concentrated on advancing researchers’ and breeders’ skills and resources in developing countries. Through this work, scientists have been able to characterise maize germplasm using improved trait observation and characterisation methods (phenotyping), implement molecular-breeding programmes, enhance strategic data management and build local human and infrastructure capacity.

The ultimate goal of the international research collaboration on comparative genomics in maize was to improve maize yields grown on acidic soils under drought conditions in Kenya and other African countries, as well as in Latin America. Seven institutes partnered up to for the comparative genomics research: Moi University, KALRO, EMBRAPA, Cornell University, the United States Department of Agriculture (USDA), JIRCAS and the International Rice Research Institute (IRRI).

“Before funding by GCP, we were mainly working on maize to develop breeding products resistant to disease and with increased yield,” says Sam. “At that time we had not known that soil acidity was a major problem in the parts of Kenya where we grow maize and sorghum. GCP knew that soil acidity could limit yields, so in the work with GCP we managed to characterise most of our acid soils. We now know that it was one of the major problems for limiting the yield of maize and sorghum.

“The relationship to EMBRAPA and Cornell University is one of the most important links we have. We developed material much faster through our collaboration with our colleagues in the advanced labs. I can see that post-GCP we will still want to communicate and interact with our colleagues in Brazil and the USA to enable us to continue to identify molecular materials that we discover,” he says. Sam and other maize researchers across Kenya, including Dickson, have since developed inbred, hybrid and synthetic varieties with improved aluminium tolerance for acid soils, which are now available for African farmers.

Photo: N Palmer/CIAT

A Kenyan maize farmer.

“We crossed them [the new genes identified to have aluminium tolerance] with our local material to produce the materials we required for our conditions,” says Sam.

“The potential for aluminium-tolerant and phosphorous-efficient material across Africa is great. I know that in Ethiopia, aluminium toxicity from acid soil is a problem. It is also a major problem in Tanzania. It is a major problem in South Africa and a major problem in Kenya. So our breeding work, which is starting now to produce genetic materials that can be used directly, or could be developed even further in these other countries, is laying the foundation for maize improvement in acid soils.”

Sam is very proud of the work: “Several times I have felt accomplishment, because we identified material for Kenya for the first time. No one else was working on phosphorous efficiency or aluminium tolerance, and we have come up with materials that have been tested and have become varieties. It made me feel that we’re contributing to food security in Kenya.”

Photo: N Palmer/CIAT

Maize grain for sale.

Maize for meat: GCP’s advances in maize genetics help feed Asia’s new appetites

Reaping from the substantial advances in maize genetics and breeding, researchers in Asia were also able to enhance Asian maize genetic resources.

Photo: D Mowbray/CIMMYT

A pig roots among maize ears on a small farm in Nepal.

Bindiganavile Vivek, a senior maize breeder for CIMMYT based in India, has been working with GCP since 2008 on improving drought tolerance in maize, especially for Asia, for two reasons: unrelenting droughts and a staggering growth the importance of maize as a feedstock. This work was funded by GCP as part of its Maize Research Initiative.

“People’s diets across Asia changed after government policies changed in the 1990s. We had a more free market economy, and along with that came more money that people could spend. That prompted a shift towards a non vegetarian diet,” Vivek recounts.

“Maize, being the number one feed crop of the world, started to come into demand. From the year 2000 up to now, the growing area of maize across Asia has been increasing by about two percent every year. That’s a phenomenal increase. It’s been replacing other crops – sorghum and rice. There’s more and more demand.

“Seventy percent of the maize that is produced in Asia is used as feed. And 70 percent of that feed is poultry feed.”

In Vietnam, for example, the government is actively promoting the expansion of maize acreage, again displacing rice. Other Asian nations involved in the push for maize include China, Indonesia and The Philippines.

Photo: A Erlangga/CIFOR

A farmer in Indonesia transports his maize harvest by motorcycle.

The problem with this growth is that 80 percent of the 19 million hectares of maize in South and Southeast Asia relies on rain as its only source of water, so is prone to drought: “Wherever you are, you cannot escape drought,” says Vivek. And resource-poor farmers have limited access to improved maize products or hybrids appropriate for their situation.

Vivek’s research for GCP focused on the development – using marker-assisted breeding methods, specifically marker-assisted recurrent selection (MARS) – of new drought-tolerant maize adapted to many countries in Asia. His goal was to transfer the highest expression of drought tolerance in maize into elite well-adapted Asian lines targeted at drought-prone or water-constrained environments.

Asia’s existing maize varieties had no history of breeding for drought tolerance, only for disease resistance. To make a plant drought tolerant, many genes have to be incorporated into a new variety. So Vivek asked: “How do you address the increasing demand for maize that meets the drought-tolerance issue?”

The recent work on advancing maize genetics for acid soils in the African and Brazilian GCP projects meant it was a golden opportunity for Vivek to reap some of the new genetic resources.

“This was a good opportunity to use African germplasm, bring it into India and cross it to some Asia-adapted material,” he says.

Photo: E Phipps/CIMMYT

Stored maize ears hanging in long bunches outside a house in China.

A key issue Vivek faced, however, was that most African maize varieties are white, and most Asian maize varieties are yellow. “You cannot directly deploy what you breed in Africa into Asia,” Vivek says. “Plus, there’s so much difference in the environments [between Africa and Asia] and maize is very responsive to its environment.”

The advances in marker-assisted breeding since the inception of GCP contributed significantly towards the success of Vivek’s team.

“In collaboration with GCP, IITA, Cornell University and Monsanto, CIMMYT has initiated the largest public sector MARS breeding approach in the world,” says Vivek.

The outcome is good: “We now have some early-generation, yellow, drought-tolerant inbred germplasm and lines suitable for Asia.

“GCP gave us a good start. We now need to expand and build on this,” says Vivek.

GCP’s supported work laid the foundation for other CIMMYT projects, such as the Affordable, Accessible, Asian Drought-Tolerant Maize project funded by the Syngenta Foundation for Sustainable Agriculture. This project is developing yet more germplasm with drought tolerance.

A better picture: GCP brightens maize research

Dickson Ligeyo’s worries of a stormy future for Kenya’s maize production have lifted over the 10 years of GCP. At the end of 2014, Kenya had two new varieties that were in the final stage of testing in the national performance trials before being released to farmers.

“There is a brighter picture for Kenya’s maize production since we have acquired acid-tolerant germplasm from Brazil, which we are using in our breeding programmes,” Dickson says.

In West Africa, researchers are also revelling in the opportunity they have been given to help enhance local yields in the face of a changing climate. “My institute benefited from GCP not only in terms of human resource development, but also in provision of some basic equipment for field phenotyping and some laboratory equipment,” says Allen Oppong in Ghana.

“Through the support of GCP, I was able to characterise maize landraces found in Ghana using the bulk fingerprinting technique. This work has been published and I think it’s useful information for maize breeding in Ghana – and possibly other parts of the world.”

The main challenge now for breeders, according to Allen, is getting the new varieties out to farmers: “Most people don’t like change. The new varieties are higher yielding, disease resistant, nutritious – all good qualities. But the challenge is demonstrating to farmers that these materials are better than what they have.”

Photo: CIMMYT

This Kenyan farmer is very happy with his healthy maize crop, grown using an improved variety during a period of drought.

Certainly GCP has strengthened the capacity of researchers across Africa, Asia and Latin America, training researchers in maize breeding, data management, statistics, trial evaluations and phenotyping. The training has been geared so that scientists in developed countries can use genetic diversity and advanced plant science to improve crops for greater food security in the developing world.

Elliot Tembo, a maize breeder with the private sector in sub-Saharan Africa says: “As a breeder and a student, I have been exposed to new breeding tools through GCP. Before my involvement, I was literally blind in the use of molecular tools. Now, I am no longer relying only on pedigree data – which is not always reliable – to classify germplasm.”

Allen agrees: “GCP has had tremendous impact on my life as a researcher. The capacity-building programme supported my training in marker-assisted selection training at CIMMYT in Mexico. This training exposed me to modern techniques in plant breeding and genomics. Similarly, it built my confidence and work efficiency.”

There is no doubt that GCP research has brightened the picture for maize research and development where it is most needed: with researchers in developing countries where poor farmers and communities rely on maize as their staple food and main crop.

More links

Photo: N Palmer/CIAT

A farmer displays maize harvested on his farm in Laos.

Jun 192015
 
Photo: N Palmer/CIAT

Bean Market in Kampala, Uganda.

Common beans are the world’s most important food legume, particularly for subsistence and smallholder farmers in East and Southern Africa. They are a crucial source of protein, are easy to grow, are very adaptable to different cropping systems, and mature quickly.

To some, beans are ‘a near-perfect food’ because of their high protein and fibre content plus their complex carbohydrates and other nutrients. One cup of beans provides at least half the recommended daily allowance of folate, or folic acid – a B vitamin that is especially important for pregnant women to prevent birth defects. One cup also supplies 25–30 percent of the daily requirement of iron, 25 percent of that of magnesium and copper, and 15 percent of the potassium and zinc requirement.

Unfortunately, yields in Africa are well below their potential – between 20 and 30 percent below. The main culprit is drought, which affects 70 percent of Africa’s major bean-producing regions. Drought is especially severe in the mid-altitudes of Ethiopia, Kenya, Malawi and Zimbabwe, as well as across Southern Africa.

“For the past seven or eight years, rains have been very unreliable in central and northern Malawi,” says Virginia Chisale, a bean breeder with Malawi’s Department of Agricultural Research and Technical Services.

“In the past, rains used to be very reliable and people were able to know the right time to plant to meet the rains in critical conditions,” she says. “Now these primary agriculture regions are either not receiving rain for long periods of time, or rains are not falling at the right time.”

Virginia recounts that during the 2011/12 cropping season there were no rains soon after planting, when it is important that beans receive moisture. Such instances can cut bean yields by half.

Photo: N Palmer/CIAT

Steve Beebe in the field.

“Drought is a recurrent problem of rainfed agriculture throughout the world,” says Steve Beebe, a leading bean breeder with the International Center for Tropical Agriculture (CIAT). “Since over 80 percent of the world’s cultivated lands are rainfed, drought stress has major implications for global economy and trade.”

Steve was the Product Delivery Coordinator for the beans component of the Legumes Research Initiative (RI), part of Phase II of the CGIAR Generation Challenge Programme (GCP). The RI incorporated several projects, the biggest of which was Tropical Legumes I (TLI) (see box). The main objective of the work on beans within TLI was to identify and develop drought-tolerant varieties using marker-assisted breeding techniques. The resulting new varieties were then evaluated for their performance in Ethiopia, Kenya, Malawi and Zimbabwe.

“It’s vital that we develop high-yielding drought-tolerant varieties so as to help farmers, particularly in developing countries, adapt to drought and produce sustained yields for their families and local economies,” says Steve.

The Tropical Legumes I project (TLI) was initiated by GCP in 2007 and subsequently incorporated into the Programme’s Legumes Research Initiative (RI). The goal of the RI was to improve the productivity of four legumes – beans, chickpeas, cowpeas and groundnuts – that are important in food security and poverty reduction in developing countries, by providing solutions to overcome drought, poor soils, pests and diseases. TLI was led by GCP and focussed on Africa. Work on beans within TLI was coordinated by the International Center for Tropical Agriculture (CIAT). The partners in the four target countries were Ethiopia’s South Agricultural Research Institute (SARI), the Kenya Agricultural Research Institute (now known as the Kenya Agricultural and Livestock Research Organization, KALRO), Malawi’s Department of Agricultural Research and Technical Services (DARTS) and Zimbabwe’s Crop Breeding Institute (CBI) of the Department of Research and Specialist Services (DR&SS). Cornell University in the USA was also a partner. Tropical Legumes II (TLII) was a sister project to TLI, led by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) on behalf of the International Institute of Tropical Agriculture (IITA) and CIAT. It focussed on large-scale breeding, seed multiplication and distribution primarily in sub-Saharan Africa and South Asia, thus applying the ‘upstream’ research results from TLI and translating them into breeding materials for the ultimate benefit of resource-poor farmers. Many partners in TLI also worked on projects in TLII.

For an overview of the work on beans from the perspectives of four different partners, watch our video below, “The ABCs of bean breeding”.

What makes a plant drought tolerant?

The question of what makes a plant drought tolerant is one that breeders have debated for centuries. No single plant characteristic or trait can be fully responsible for protecting the plant from the stress of intense heat and reduced access to water.

“It’s a difficult question to answer for any plant, including beans,” says Steve. “Once you do isolate a trait genetically, it can often be difficult to identify this trait in a plant in the field, for example, identifying the architecture and length of a plant’s roots.”

Phenotyping is an important process in conventional plant breeding. It involves identifying and measuring the presence of physical traits such as seed colour, pod size, stem thickness or root length. Gathering data about a range of such characteristics across a number of different plant lines helps breeders decide which plants to use as parents in crosses and which of the progeny have inherited useful traits.

Root length has long been thought of as a drought-tolerance trait: the longer the root, the more chance it has of tapping into moisture stored deeper in the soil profile.

Given, however, that it is difficult to inspect root length in the field, researchers at CIAT have been exploring other more accessible drought-tolerance traits they can more easily identify and measure. One of these is measuring the weight of the plants’ seeds.

Photo: N Palmer/CIAT

Comparison between varieties in trials of drought tolerant beans at CIAT’s headquarters in Colombia.

Fat beans indicate plants coping with drought stress

“We measure seed weight because we are discovering that under drought stress, drought-tolerant bean varieties will divert sugars from their leaves, stems and pods to their seed,” says Steve. “We call this trait ‘pod filling’, and for us it is the most important drought-tolerance trait to be found over the last several years.”

Finding bean plants with larger, heavier seeds when growing under drought conditions indicates that the plants are coping well, and means farmers’ yields are maintained.

As part of GCP’s Legumes RI, African partners like Virginia have been measuring the seed weight of several advanced breeding lines, which can be used as parents to develop new varieties. These breeding lines have been bred by CIAT and demonstrate this pod-filling process and consequent tolerance of drought.

Although this measurement is relatively cheap and easy for breeders all over the world to do, Steve and his team are interested in finding an even more efficient way to spot plants that maintain full pods under drought.

“We are trying to understand which genes control this trait so we can use molecular-assisted breeding techniques to determine when the trait is present,” says Steve. Having identified several regions of genes related to pod filling, he and his team have developed molecular markers to help breeders identify which plants have these desired genes. “The use of molecular markers in selection significantly reduces the time and cost of the breeding process, making it more efficient. This means that we get improved varieties out to farmers more quickly.”

Photo: N Palmer/CIAT

Bean farmer in Rwanda.

Molecular markers (also known as DNA markers) are used by researchers as ‘flags’ to identify particular genes within a plant’s genome (DNA) that control desired traits, such as drought tolerance. These markers are themselves fragments of DNA that highlight particular genes or regions of genes by binding near them.

To use an analogy, think of a story as the plant’s genome: its words are the plant’s genes, and a molecular marker works like a text highlighter. Molecular markers are not precise enough to highlight specific words (genes), but they can highlight sentences (genomic regions) that contain these words (genes), making it easier and quicker to identify whether or not they are present.

Photo: J D'Amour/HarvestPlus

Beans from Rwanda.

Plant breeders can use molecular markers from early on in the breeding process to choose parents for their crosses and determine whether progeny they have produced have the desired trait, based on testing only a small amount of seed or seedling tissue.

“If the genes are present, we grow the progeny and conduct the appropriate phenotyping; if not, we throw the progeny away,” explains Steve. “This saves us resources and time because we need to grow and phenotype only the few hundred progeny which we know have the desired genes, instead of a few thousand progeny, most of which would not possess the gene.”

Outsourcing genotyping to the UK Steve says a significant contribution made by GCP was facilitating a deal with a private UK company (LGC Genomics, formerly KBioscience) that is able to quickly and cheaply genotype leaf samples sent to them by African breeders. The company then forwards the data to the International Center for Tropical Agriculture (CIAT), who analyse it and let the breeders in Africa know which progeny contain the desired genes and are suitable for breeding, and which ones to throw away.  “The whole process takes roughly four weeks, but saves the breeders the time and effort to grow all progeny,” says Steve. “This system works well for countries that don’t have the capacity or know-how to do the molecular work,” says Darshna Vyas, a plant genetics specialist with LGC Genomics. “Genotyping has advanced to a point where even larger labs around the world choose to outsource their genotyping work, as it is cheaper and quicker than if they were to equip their lab and do it themselves. We do hundreds of thousands of genotyping samples a day – day in, day out. It’s our business.”

GCP has supported this foundation work, building on the extensive bean research already done by CIAT dating back to the 1970s, to develop molecular markers not only for drought-tolerance traits such as pod filling, but also for traits associated with resistance to important insect and disease menaces.

“Under drought conditions, plants become more susceptible to pests and diseases, so it was important that we also try to identify and include resistance traits in the drought-tolerant progeny,” says Steve.

Drought is but one plant stressor – diseases and pests wreak havoc too

Photo: W Arinaitwe/CIAT/PABRA

Common bacterial blight on bean.

The bean diseases that farmers in Ethiopia, Kenya, Malawi and Zimbabwe continually confront are angular leaf spot, bean common mosaic virus, common bacterial blight and rust. Key insect pests are bean stem maggot and aphids.

“We’ve had reports of bean stem maggot and bean common mosaic virus wiping out a whole field of beans,” says Virginia. “Although angular leaf spot and common bacterial blight are not as damaging, they can still reduce yields by over 50 percent.”

Virginia says this is devastating for farmers in Malawi, many of whom only have enough land and money to grow beans to feed their families and sell what little excess there is at market to purchase other necessities.

“This is why we are excited by the prospect of developing not just drought-tolerant varieties, but drought-tolerant varieties with disease and pest resistance as well,” says Virginia.

Virginia’s team in Malawi – along with other breeders in Ethiopia, Kenya and Zimbabwe – are currently using over 200 Mesoamerican and Andean bean breeding lines supplied by CIAT to help breed for drought tolerance and disease and pest resistance. Although many do not yet have the capacity to do molecular breeding in their countries, thanks to advances in plant science it is becoming more feasible and cheaper to outsource molecular breeding stages of the process (see box above).

“With help from GCP and CIAT, we have successfully crossed a line from CIAT with some local varieties to produce plants that are high yielding and resistant to most common bean diseases,” Virginia says.

Photo: ILRI

Malawian farmer Jinny Lemson grows beans to feed her livestock.

Ethiopia’s new bean breeders

Photo: ILRI

Young women sorting beans after a harvest in Ethiopia.

One man who has been helping build this new breeding capacity is Bodo Raatz, a molecular geneticist who joined CIAT and GCP’s Legumes RI in late 2011.

“We’ve [CIAT] hosted several African PhD students here in Colombia and have conducted several workshops in Colombia and Africa too,” says Bodo.

“At the workshops we teach local breeders and technicians how to use genetic tools and markers for advanced breeding methods, phenotyping and data management. The more people there are who can do this work, the quicker new varieties will filter through to farmers.”

Bodo says he has found delivering the training both personally and professionally rewarding, especially “seeing the participants understand the concepts and start using the tools and techniques to develop new lines [of bean varieties] and contribute to the project.”

One national breeder whom Bodo has seen advance from the training is Daniel Ambachew, then a bean breeder at the Southern Agricultural Research Institute (SARI) in Ethiopia.

Daniel started as a GCP-funded Master’s student enrolled at Haramaya University, Ethiopia, evaluating bean varieties with both tolerance to drought and resistance to bean stem maggot. He eventually became the Ethiopian project leader for beans within GCP’s Legumes RI.

“Daniel is currently one of only a handful of bean breeders in Ethiopia who are using molecular-assisted breeding techniques to breed new varieties,” says Bodo. “It’s quite an achievement, especially now that he has taken on the lead role in Ethiopia.”

Photo: N Palmer/CIAT

Buying and selling at a bean market in Kampala, Uganda.

For Daniel, learning about and using the new molecular-breeding techniques has been an exciting new challenge. “The most interesting part of the technology is that it helps us understand what is going on in the plant at a molecular level and lets us know if the crosses we are making are successful and the genes we want are present,” says Daniel. “All this helps improve our efficiency and speeds up the time it takes us to breed and release new varieties for farmers.”

By the end of 2014, Daniel and his team had finished the third year of trials and had several drought-tolerant lines ready for national trials in 2015 and eventual release in 2016.

Between 2012 and 2014, Daniel, and two other breeders from SARI, attended GCP’s three-year Integrated Breeding Multiyear Course, learning how to design molecular-assisted breeding trials; collect, analyse and interpret genotypic and phenotypic data from the trials; and manage data using the GCP’s Integrated Breeding Platform (IBP), particularly its Breeding Management System (BMS).

“The IBP is a really fantastic tool,” says Daniel. “During the course we learnt about the importance of recording clear and consistent phenotypic data, and the IBP helps us to do this as well as store it in a database. It makes it easier to refer to and learn from the past. I’m now trying to pass on the knowledge I’ve learnt as well as create and implement a data-management policy for all plant breeders and technicians in our institute.”

Bodo agrees with Daniel about the importance of IBP and believes it will be a true legacy of GCP beyond the Programme’s end in 2014. “The Platform has been designed to be the main data-management platform for plant breeders. It allows breeders to talk the same language and will reduce the need for learning new systems.”

Daniel says the challenge for his institute now is to build further capacity among staff – and to retain it. “At the moment we only have two bean breeders,” says Daniel. “It’s hard to retain research staff in Ethiopia as salaries are very low, so people move on to new, higher paying positions when they get the chance. It’s not unique to Ethiopia, but true of all Africa.”

Photo: O Thiong'o/CIAT/PABRA

Bean trials at KALRO in Kenya.

Kenya chasing higher bean yields

Across the border, Kenya has also been facing staffing issues.

“We are behind Ethiopia, Malawi and Zimbabwe in terms of our capacity and our trials,” says David Karanja, a bean breeder and project leader at the Kenya Agricultural and Livestock Research Organisation (KALRO, formerly the Kenya Agricultural Research Institute, or KARI). “At the start of the project, we didn’t have a breeder to lead the project for almost two years. However, we are now rapidly catching up with the others.”

And it’s a good thing too, as the country is in need of higher yielding beans to accommodate its population’s insatiable appetite for the crop. Out of the four target African countries, Kenya is the largest bean producer and consumer. As such, the country relies on beans imports from Ethiopia, Malawi, Tanzania and Uganda.

“A lot of families eat beans every day,” says David. “On average, the population eats 14–16 kilograms per person each year, but in western Kenya the average is over 60 kilograms.”

Photo: CIMMYT

Githeri, a Kenyan staple food made with maize and beans.

Kenyans consume an average total of 400,000 tonnes of beans each year, consistently more than the country produces. Projected trends in population growth indicate that this demand for beans will continue to increase by three to four percent annually.

Even though the area planted to beans has been increasing, David says farmers and breeders need to work together to improve productivity, which is well below where it should be. “The national average yield is 100 kilograms per hectare, which can range from 50 kilograms up to 700 kilograms, depending on whether we experience a drought, or a pest or disease epidemic,” explains David. “The minimum target we should be aiming for is 1,200 kilograms per hectare.”

Such a figure may seem impossible, but David believes that new breeding techniques and the varieties KALRO are producing with the help of CIAT are providing hope that farmers can reach these lofty goals.

“We have several bean lines that are showing good potential to produce higher yields under drought conditions and also have resistance to diseases like rust and mosaic virus,” says David. “They are currently under national trials, and we are confident these will be released to farmers in 2015.”

Photo: O Thiong'o/CIAT/PABRA

Varieties fare differently in KALRO bean trials in Kenya.

Commercialising beans

Photo: CIAT

Maturing bean pods.

“Many subsistence farmers have limited access to good quality bean seeds; they lack knowledge of good crop, pest and disease management; and they have poor post-harvest storage facilities,” says Godwill Makunde, who was previously a breeder at Zimbabwe’s Crop Breeding Institute (CBI) and leader of GCP’s Legumes RI bean project in Zimbabwe.

TLI’s sister project, Tropical Legumes II (TLII, see box above), led by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), provided the route by which the upstream work of TLI would have impact in helping these farmers, seeking to deliver the new varieties developed under TLI into their hands. As part of TLII, Godwill, his successor Bruce Mutari, and other African partners worked on developing sustainable seed systems.

“Because beans are self-pollinating, which means each crop is capable of producing seed exactly as it was sown, farmers tend to propagate seed on farm,” says Godwill. “While this can be cost effective, it can reduce farmers’ access to higher yielding, tolerant lines, like the ones we are currently producing.”

In none of the partner countries of TLI and TLII are there formal systems for producing and disseminating bean seeds. Godwill and other partners are working with seed companies on developing a sustainable model where both farmers and seed companies can benefit.

Success built on a solid foundation

Photo: N Palmer/CIAT

Field workers tend beans in Rwanda.

A key to the success of the beans component of GCP’s Legumes RI, according to Ndeye Ndack Diop, GCP’s Capacity Building Theme Leader and TLI Project Manager, has been partners’ existing relationships with each other.

“Many of the partners are part of a very strong network of bean breeders: the Bean Coordinated Agricultural Project [BeanCAP],” explains Ndeye Ndack, adding that the TLI and BeanCAP networks benefited each other.

BeanCAP released more than 1,500 molecular markers to TLI researchers, which have helped broaden the genetic tools available to developing-country bean breeders.

TLI was also able to leverage and advance previous BeanCAP work and networks. For example, it was through this collaboration that GCP was introduced to LGC Genomics, a company it then worked with on many other crop projects.

To sustain integrated breeding practices beyond the Programme’s close in 2014, GCP established Communities of Practice (CoPs) that are discipline- and commodity-oriented.

“GCP’s CoP for beans has also helped to broaden both the TLI and BeanCAP networks too,” says Ndeye Ndack. “The ultimate goal of the CoPs is to provide a platform for community problem solving, idea generation and information sharing.”

Developing physical capacity

Besides developing human capacity, GCP has also invested in developing infrastructure in Ethiopia, Kenya and Zimbabwe.

SARI now has an irrigation system to enable them to conduct drought trials year round. “We have 12.5 hectares of irrigation now, which we use to increase our efficiency and secure our research,” says Daniel. “We can also increase seed with this irrigation during the off-season and develop early generation seeds for seed producers.”

In Zimbabwe, CBI received specialised equipment that enables them to extract DNA and send it for genotyping in the UK.

Both SARI and CBI also received automatic weather stations from GCP for high-precision climatic data capture, with automated data loading and sharing with other partners in the network.

Delivering the right beans to farmers

Back in Malawi, Virginia says another important facet of the TLII project is that researchers understand what qualities farmers want in their beans. “It’s no use developing higher yielding beans if the farmer doesn’t like the colour, or they don’t taste nice,” she says. “For example, consumers in central Malawi prefer khaki or ‘sugar beans’, which are tan with brown, black or red speckles. While those in southern Malawi tend to prefer red beans. Farmers know this and will grow beans that they know consumers will want.”

Photo: N Palmer/CIAT

Diversity at bean market in Masaka, Uganda.

Breeders in all four countries have been conducting workshops and small trials with farmers to find out this information. In Kenya, David finds farmer participation a great way to promote the work they are doing and show the impact the new drought-tolerant and disease-resistant lines can have.

“Farmers are excited and want to grow these varieties immediately when they see for themselves the difference in yield these new varieties can produce compared to their regular varieties,” says David. “They understand the pressure on them to produce more yields and are grateful that these varieties are becoming more readily available as well as tailored to their needs.”

For Steve, such anecdotes provide him and his collaborators with incentives to continue their quest to discover more molecular markers associated with drought tolerance, post-GCP.

“It’s a testament to everyone involved that we have been able to develop these advanced lines with pod-filling traits using molecular techniques, and make them available to farmers in six years instead of ten,” says Steve.

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Jun 052015
 
Photo: Bill & Melinda Gates Foundation

Farmer Maria Mtele holds recently harvested orange-fleshed sweetpotatoes in a field in Mwasonge, Tanzania.

Sweetpotato has a long history as a lifesaver. The Japanese used it when typhoons demolished their rice fields. It kept millions from starvation in famine-plagued China in the early 1960s and came to the rescue in Uganda in the 1990s, when a virus ravaged the cassava crop.

In sub-Saharan Africa, sweetpotato is proving crucial in the fight against blindness, disease and premature death among children under five. And, as agriculture becomes more market-oriented across the continent, sweetpotato has some significant advantages: it requires fewer inputs and less labour than other crops such as maize, tolerates marginal growing areas and can mature within four months.

On these fertile grounds, researchers across the globe are not underestimating the importance of sweetpotato as a staple crop.

“Yields achieved by resource-poor farmers in sub-Saharan Africa are typically low,” says Roland Schafleitner of the International Potato Center (CIP), based in Peru.

“Improved and well-adapted sweetpotato varieties with increased tolerance to drought, pests and diseases will have a positive impact on food and income security in sub-Saharan Africa and can significantly contribute to increasing productivity,” he says.

Roland was Principal Investigator of two research projects funded by the CGIAR Generation Challenge Programme (GCP), which developed genetic and genomic resources for breeding improved sweetpotato.

At the outset of the work, Roland says: “Breeding efforts were limited by the crop’s genetic complexity and the lack of information available about its genetic resources.

“It was clear that if we could develop genetic tools and make concerted efforts towards understanding the gene pool of sweetpotato, the breeding potential of the crop would improve.”

Photo: Bill & Melinda Gates Foundation

Farmer Mwanaidi Rhamdani at work in an orange-fleshed sweetpotato field in Mwasonge, Tanzania.

Sub-Saharan Africans getting their vitamin A from sweetpotato

Photo: CIP

Sweetpotato diversity.

Malnutrition does not always mean a simple lack of calories; research suggests that nutrient shortfalls are an even bigger killer. Vitamin A deficiency is a leading cause of blindness, infectious disease and premature death among children under five and pregnant women in sub-Saharan Africa and Asia.

Sweetpotato comes in a wide range of colours. Varieties with dark orange flesh are naturally very rich in the pigment beta-carotene, which the body converts into vitamin A. However, the sweetpotatoes traditionally grown in Africa are pale-fleshed and low in beta-carotene. African consumers were not used to eating colourful sweetpotato – and these orange-fleshed varieties were in any case not well adapted African growing conditions.

Recent years have therefore seen a collaborative effort by researchers across the world to breed orange-fleshed sweetpotato varieties fortified with high levels of beta-carotene, and even enriched with other nutrients, that have also been crossed with local varieties and so are adapted to local conditions and tastes. A crucial part of these efforts has also been to create public awareness and encourage people to grow, eat and buy these new varieties.

Photo: HarvestPlus

Two cheeky young chappies from Mozambique enjoy the sweet taste of orange-fleshed sweetpotato rich in beta-carotene, or pro-vitamin A.

All of this adds to the growing momentum behind sweetpotato. The growing awareness of sweetpotato’s potential nutritional benefits for the poor and food insecure, as well as its value for subsistence farmers as a reliable crop that withstands drought and requires minimal inputs, mean that it is growing in significance.

Photo: HarvestPlus

Orange-fleshed sweetpotato can be used to make a variety of tasty products from doughnuts to chapati.

More than 95% of the world’s sweetpotato crop is grown in developing countries, where it is the fifth most important staple food crop. It is particularly important in many African countries: Madagascar in Southern Africa; Nigeria in West Africa; and those surrounding the Great Lakes in East and Central Africa – Uganda, Malawi, Angola and Mozambique.

According to 2013 figures from the Food and Agriculture Organization of the United Nations, 3.6 million hectares of sweetpotato were harvested in Africa. While the average global yield of sweetpotato per hectare was 14.8 tonnes, across all East African countries in 2013 it was only half this, at 7.1 tonnes per hectare. In West African nations the average yield was even worse, at 3.7 tonnes per hectare.

Farmers are unable to make the most of their crops because the varieties available to them, including traditional varieties (or landraces) have low resistance to viral diseases and insect pests, and poor tolerance to drought. It is therefore crucial that when developing new varieties breeders are able to efficiently incorporate pest and disease resistance and drought tolerance traits.

Sweetpotato, in spite of its name, is only distantly related to the potato. Unlike the potato – which is a tuber, or thickened stem – the sweetpotato is a root. Sweetpotato is not related to the yam either, despite the physical similarity between the two. Sweetpotato can grow at altitudes ranging from sea level to 2,500 metres. It requires fewer inputs and less labour than other crops such as maize, and, in contrast to the potato, it can tolerate heat.

New DNA markers identified for sweetpotato disease

The sweetpotato virus disease (SPVD) is the most serious disease affecting sweetpotato in sub-Saharan Africa. It often causes serious yield losses of up to 80–90 percent.

The disease is the result of joint infection by two viruses: the sweetpotato feathery mottle virus and the sweetpotato chlorotic stunt virus. Of the two, the stunt virus is the more problematic.

Wolfgang Grüneberg, also from CIP, says that, in the years 2006–2008, 52 new DNA markers were developed as part of GCP-funded research to improve marker-assisted selection for resistance to the disease.

“The results,” says Wolfgang, Principal Investigator for the research, “looked promising for developing a large number of orange-fleshed sweetpotatoes with resistance to SPVD.”

Immediately following the development of the markers, two varieties of sweetpotato were developed using a cloned gene, Resistan, known to confer resistance to the virus. The first variety was used to improve an SPVD test system so that the disease could be diagnosed earlier if a crop was affected. The second variety underwent field tests in regions in Uganda that were highly affected by the disease.

Photo: HarvestPlus

Sweetpotato vines and roots.

Mobilising the genetic diversity of sweetpotato for breeding

The goals of the GCP-supported work were to develop a diverse genetic resource base for sweetpotato and stimulate the use of new tools in ongoing breeding programmes.

To help transfer this work from high-end laboratories to resource-poor research labs in developing countries, GCP promoted collaboration across institutions and borders. Researchers from Brazil, Mozambique, Uganda and Uruguay worked together on sweetpotato genetic research projects.

As Roland explains, the basic first steps needed to begin to ‘mobilise’ the genetic diversity of sweetpotato were developing a reference set of varieties and improving genomics tools to work with polyploid crops, i.e. those possessing multiple sets of chromosomes, such as sweetpotato.

GCP-supported researchers in Peru and sub-Saharan Africa defined a reference set of 472 varieties of sweetpotato, carefully selected and honed to represent both the diversity of the crop and its most important agronomical and nutritional traits.

“Based on a reference set, genetic markers can be developed that are associated with important characteristics of the crop and can help breeders to select favourable genotypes,” says Roland.

The gene sequences developed during the Programme are now available as a Sweetpotato Gene Index.

“Based on these sequences,” says Roland, “molecular markers have been designed that can help breeders and gene-bank curators to assess the genetic diversity of their accessions and to perform genetic mapping studies.

“Today, techniques that yield a much larger number of markers for genetic studies and selection are accessible for sweetpotato,” he says.

Photo: Bill & Melinda Gates Foundation

Mwanaidi Rhamdani (left) works with Maria Mtele in an orange-fleshed sweetpotato field in rural Tanzania.

The genetic lifelines reach Africa

Sweetpotato is one of the most important staple crops in Mozambique, ranking in third position after cassava and maize. The areas harvested in Mozambique in 2013 were 1.7 million hectares of maize, 780,000 hectares of cassava and 120,000 hectares of sweetpotato.

Photo: CIP

A child eats cooked orange-fleshed sweetpotato in Uganda.

GCP funded breeders in Mozambique and Uganda to learn how to identify genetic markers that would prove useful for future sweetpotato breeding.

“Our African partners visited us at CIP and helped us complete the work on identifying markers,” recalls Roland. “This provided the opportunity for direct ‘technology transfer’ to breeders in the target region.”

The collaboration had, for the first time, created a critical amount of genetic and genomics resources for sweetpotato. The resulting Sweetpotato Gene Index and the new markers were published in a peer-reviewed journal, BMC Genomics (2010) 11:604.

The new genetic resources are in use at CIP in Peru and in breeding programmes in Burkina Faso, Mozambique, Uganda, Uruguay and the USA for the assessment of the genetic diversity of germplasm collections.

“The markers have been used for diversity analysis, especially at the CIP gene bank, and also in Africa,” says Roland, who says the markers will help future research.

“Such analysis guides germplasm conservation decisions, and diversity studies are a great tool to develop core collections and composite genotype sets – subsets of the whole collection – which allow for more practical screening for specific traits than large collections.”

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Photo: P Casier/CGIAR

Kenyan farmer Emily Marigu with her sweetpotatoes.

Jun 022015
 
Photo: S Edmeades/IFPRI

A farmer transports bananas to market by bicycle in Uganda.

At whatever time of the day or night you are reading this, somewhere in the world there are sure to be farmers trekking many kilometres to take their bananas to local markets. These small-scale farmers produce almost 90 percent of the world’s bananas, and make up a significant portion of the 400 million people around the globe’s tropical girdle – Africa, Asia and Latin America – who rely on bananas for food and a source of income.

Bananas are often called the world’s most popular fruit, and global production in 2012 was almost 140 million tonnes. India is the largest producer, while South and Central American farmers supply the most to international supermarket shelves, exporting 80 percent of their bananas.

The importance of the banana as a food crop in tropical areas cannot be underestimated. More than a simple snack, plantain-type bananas in particular are a key component in savoury dishes. In Central and East African countries – like Cameroon, Gabon, Rwanda and Uganda – one person will eat an average of between 100 kg and 250 kg of banana each year. That equates to somewhere between 800 and 2000 average-sized bananas. In those four countries, bananas account for up to a quarter of people’s daily calorie intake.

Photo:  A Vezina/Bioversity International

A stallholder offers bananas for sale at a fruit market in Nairobi, Kenya.

Banana’s asexuality inhibits its resilience

Photo: G Stansbury/IFPRI

Bananas growing in Rwanda.

Banana propagates though asexual reproduction. This means that all the bananas of each variety are genetically identical, or nearly so, and therefore susceptible to the same diseases. Indeed, the world has already lost almost its entire banana crop once: before the 1950s, the Gros Michel cultivar dominated banana exports, but it was gradually wiped out in most regions by Panama disease, caused by the fungus Fusarium oxysporum. Furthermore, with reproduction being asexual, it is difficult to develop new, resistant varieties through conventional breeding.

At the turn of the twenty-first century, pests and diseases were once again becoming a real threat to global banana production. Little genetic research had been done on the fruit, and only a small portion of its genes had been used in breeding new varieties in its 7,000-year history as a cultivated crop.

“Several research groups had developed genetic markers for bananas [‘flags’ on the genome that can be linked to physical traits], but there was no coordination and only sketchy germplasm studies,” recalls Jean Christophe Glaszmann from CIRAD (Centre de coopération internationale en recherche agronomique pour le développement; Agricultural Research for Development) in France.

Photo: N Palmer/CIAT.

A plantain farmer walks through a plantation in Quindió, Colombia.

“It was not a priority,” says Jean Christophe, who was Subprogramme Leader for Genetic Diversity for the CGIAR Generation Challenge Programme (GCP), an international initiative established in 2004 to encourage the use of genetic diversity and advanced plant science to improve crops.

But between 2004 and 2012, under GCP, a wealth of research work was undertaken that culminated in the complete genetic sequencing of banana. It was a long process, says Jean Christophe, but the GCP-funded work on banana made a significant contribution to important results.

The extensive data on the genetics of banana are now available to scientists worldwide, who can use it to delve deeper into banana’s genes to breed varieties that can sustain the poorer populations in developing countries.

Once finally sequenced, the banana genome was published in one of the most prestigious scientific journals, Nature, in July 2012: “The reference Musa [banana and plantains] genome sequence represents a major advance in the quest to unravel the complex genetics of this vital crop, whose breeding is particularly challenging. Having access to the entire Musa gene repertoire is a key to identifying genes responsible for important agronomic characters, such as fruit quality and pest resistance.”

Filling and full of fuel, and with the major advantage that it fruits year-round, the banana is vital to food security in the tropics. Bananas are potassium-rich and supply people in developing countries with a major source of carbohydrates. They also provide vitamin A, niacin, vitamin B6, thiamine, riboflavin and folic acid.

Passionate people pooled for the work

Photo: UN Women Asia & the Pacific

A banana seller in Hanoi, Vietnam.

Plans to sequence the banana genome started taking shape in 2001 at Bioversity International (a CGIAR centre), where a group of scientists formed the Global Musa Genomics Consortium. At that time, the only plant whose genome had been sequenced was Arabidopsis thaliana (a small flowering plant related to cabbage and mustard, used as a model organism in plant science), with rice close behind.

CGIAR established GCP in 2004 “to tap into the rich genetic diversity of crops via a global network of partnerships and breeding programmes,” according to Hei Leung, who was instrumental to GCP’s foundation and a Subprogramme Leader for Comparative Genomics. (During its first phase GCP was organised by Subprogramme; these were later replaced by Research Themes and Research Initiatives.)

Hei acknowledges that banana was ‘somewhat on the fringe’ of GCP’s main focus on improving drought tolerance in crops. However, he says, it was still relevant for GCP to support the emergence of improved genetics for banana.

The work we did in genetic diversity is about future generations. We wanted a programme that is pro-poor, meaning that the majority of the people in the world are depending on [the crop].

Photo: Adebayo/IITA

A typical banana and plantain market at Ikire in Osun State, Nigeria.

“Drought tolerance is a good candidate because drought affects a lot of poor areas, but you really cannot just take one trait as pro-poor. We had a highly motivated group of researchers willing to devote their efforts to Musa,” says Hei.

“Nicolas Roux at Bioversity International was a passionate advocate for the partnership,” notes Hei. “The GCP community offered a framework for novel interactions among banana-related actors and players working on other crops, such as rice.”

Nicolas concurs on the potential for a little banana research to have great value: “Even though banana is among the most important basic food crops for 400 million people, and 100 million tonnes are grown annually on over 10 million hectares in 120 countries, it’s still under-researched and underfunded.”

The resultant research team was led by Japan’s National Institute of Agrobiological Sciences, which had vast experience in rice genome sequencing.

“So, living up to its name as a Challenge Programme, GCP decided to take the gamble on banana genomics and help it fly,” says Hei.

To advance genetics, you first need the intelligence

Photo: IITA

Banana bunches on an experimental plot at IITA.

Three global research agencies were charged with working together to develop a reference set for banana: Bioversity International, CIRAD, and the International Institute of Tropical Agriculture (IITA).

Creating a reference set – a careful, tactical selection representing the genetic diversity of a crop – is an invaluable first step in enabling scientists to work together to develop more ‘intelligent’ genetic data.

“Initially, we put together a community of institutions that have collections [of banana germplasm],” explains Jean Christophe. “And then we put together these initial materials that we sample in order to develop representative subsamples – this is called a ‘composite’ set because it comes from different institutions.

“Then we genotype this composite collection, and the genotyping allows us to understand how all this [genetic material] is structured. Based on how it is structured, we can re sample a smaller representation – this is what becomes a reference set.”

So, in the case of crops with an extensive genetic resource base, such as rice, there may be more than 100,000 different plant samples, or accessions, that are reduced to a few thousand. For banana, which has a smaller genetic resource base, a few hundred thousand accessions can be reduced to a few dozen.

“A couple of hundred accessions or fewer become manageable for plant breeders or crop specialists. And we want this to serve as a reference, shared among people, so that everybody works on the same reference material,” says Jean Christophe.

“If you work on the same reference material, you can compile information that is more intelligent – you can have the crop specialist who says ‘this is resistant; this is tolerant; this is susceptible’, and you can also have the biochemist, you can have the physiologist; in the end, you can compile the information.”

“We analysed about 500 accessions and narrowed it down to 50,” says Jean Christophe. This reference collection is currently stored at the University of Leuven in Belgium.

The refined data collected on the banana reference set enabled the researchers to unravel the origin and genealogy of the most important dessert banana: the Cavendish, the cultivar subgroup that dominates banana exports worldwide. Thanks to the early GCP work, they were able to show that Cavendish bananas evolved from three markedly different subspecies.

Photo: C Sokunthea/World Bank

65-year-old Cambodian farmer, Khout Sorn, stands in front of his banana trees in Aphiwat Village, Tipo commune, Cambodia.

Malaysian wild subspecies fully sequenced

During these preliminary years of GCP-supported research on banana, the Programme funded several other smaller projects to consolidate genomic resources available for banana. Scientists developed libraries of artificial chromosomes that can be used in sequencing the DNA of banana, as well as genetic maps, which according to Jean Christophe are essential for improving the quality of the sequence.

These projects contributed to the full genome sequencing of a wild banana from Malaysia’s Pahang province in 2008. The ‘Pahang’ subspecies is one of the Cavendish variety’s three ancestors, and has also been shown to have had a role in the origin of many other banana cultivars, including those that are most important for food and economic security.

“GCP did not fund the sequence [of the Pahang banana], but it funded several things that made it possible to undertake full-scale sequencing,” Jean Christophe says. “It supported the development of particular resources and tools, and this made it possible for researchers to start the full-length sequencing.”

Photo: Asian Development Bank

A farmer at work on a banana plantation, Mindanao, the Philippines.

Breeders now need to set to work

The more that is known about the genes responsible for disease resistance and other desirable traits in banana, the more researchers will be able to help farmers in developing countries to improve their yields.

“The road remains long, but now we have a good understanding of genetic diversity,” says Jean Christophe. “We have done a range of studies aimed at unravelling the genes that could control sterility in the species.

“This is undoubtedly an inspiring challenge towards unlocking the genetic diversity in this crop.

“If we have more money in the future, we are going to sequence others of the subspecies so that we can have the full coverage of the current Cavendish genome. But that was a good start,” says Jean Christophe.

“What we have to do now is to create the right populations [of banana] in the field so that we can separate out the characteristics we want to breed for.”

The new intelligence on banana genetics has given breeders the material they need that will ultimately help 400 million people in the tropics sustain food supplies and livelihoods.

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Photo: N Palmer/CIAT

Bananas on the way to market in Kenya.

May 292015
 

A little over a decade ago, a PhD student in Brazil was poring over sorghum genes, trying to isolate one that helps plants withstand acidic soils.

Photo: B Nichols/USDA

Sorghum

Scientists at the Brazilian Corporation of Agricultural Research (EMBRAPA) had been researching plants that can grow well in acidic soils since the mid-1970s.

“What we have done within the Generation Challenge Programme,” explains Jurandir Magalhães, now a senior scientist for EMBRAPA, as he reflects back on the past decade, “is speed up maize and sorghum breeding for acidic soil adaptation”.

EMBRAPA partnered with the CGIAR Generation Challenge Programme (GCP) to advance plant genetics so as to breed aluminium-tolerant crops that will improve yields in harsh environments, in turn improving the quality of life for farmers.

Almost 70 percent of Brazil’s arable land is made up of acidic soils. That means the soil has toxic levels of aluminium and low levels of phosphorous – a lethal combination that makes crop production unsustainable. Aluminium toxicity in soil comes close to rivalling drought as a food-security threat in critical tropical food-producing regions. This is because acidic soils reduce root growth and deprive plants of the nutrients and water they need to grow.

Robert Schaffert – EMBRAPA’s longest-serving sorghum breeder – had developed mapping populations for aluminium tolerance in sorghum; these populations were the basis for the work supported by GCP.

During the first four years of the 10-year Programme, Jurandir was able to identify and clone the major aluminium-tolerance gene in sorghum – AltSB – using these mapping populations. The cloned gene has since enabled researchers across Africa and Asia to quickly and efficiently breed improved sorghum and maize plants that can withstand acidic soils.

Jurandir, speaking today about the work to advance sorghum genetic resources, says: “Wherever there are acidic soils with aluminium toxicity and low phosphorous availability, our results should be applicable.”

His story with EMBRAPA is one of many where GCP-supported projects have been instrumental in helping global research centres achieve their goals, which ultimately will help farmers worldwide.

Common objectives

Jurandir is now a research scientist in molecular genetics and genomics at the EMBRAPA Maize & Sorghum research centre. He and colleagues at the centre partnered with scientists in Africa, Asia and the US to identify and clone genes in sorghum, maize and rice that confer resistance or tolerance to stresses such as soil acidity, phosphorus efficiency, drought, pests and diseases.

Photo: R Silva/EMBRAPA

Maize growing in Brazil.

“One important focus of GCP was linking basic research to applied crop breeding,” Jurandir says. “This is also the general orientation of our programme at EMBRAPA. We develop projects and research to produce, adapt and diffuse knowledge and technologies in maize and sorghum production by the efficient and rational use of natural resources.

“GCP provided both financial support and a rich scientific community that were useful to help us attain our common objectives.”

EMBRAPA’s work on cloning the AltSB gene would prove to be one of the first steps in GCP’s foundation sorghum and maize projects, both of which sought to provide farmers in the developing world with crops that will not only survive but thrive in the acidic soils where aluminium toxicity reduces crop production.

Leon Kochian of Cornell University in the US was Jurandir’s supervisor at the time when they applied for GCP funding. Leon was a Principal Investigator for various GCP research projects, researching how to improve grain yields of crops grown in acidic soils.

“The breeders are so important,” says Leon about the importance of supporting institutes such as EMBRAPA to advance plant genetics. “Ultimately, they are the cliché of ‘the rubber hits the road’. They’re the ones who translate what we’re trying to figure out into the actual crop improvements. That’s really what it’s all about.”

“That’s why EMBRAPA is a unique institution. Their mission is to get improved seed out, new germplasm out, for the farmers. They have the researchers in sorghum and maize breeding [Robert Schaffert and Sidney Parentoni] and molecular biology [Jurandir Magalhães and Claudia Guimarães].”

Photo: CIFOR

Maize farmers in Brazil.

Great minds think alike

Jurandir’s EMBRAPA colleague Claudia Guimarães, a plant molecular geneticist focusing on maize, says GCP promoted ‘products’, which also echoed the mission statement of EMBRAPA’s Maize & Sorghum research centre.

The centre’s mission is to: ‘Generate, adapt and transfer knowledge and technology that allows for the efficient production and use of maize, sorghum, and natural resources as well as promotes competitiveness in the agriculture sector, sustainable development, and the well-being of society.’

GCP, says Claudia, “wanted to extract something else from the science – products – the idea of a real, touchable product. You have to have progress: germplasm, lines, markers; they are quite practical things.

“The major goal of GCP is to deliver products that can improve people’s lives worldwide. So it needs to be readily available and useful for other scientists and for the whole community.”

GCP wanted to ensure that research products could and would be adopted, adapted and applied for the ultimate benefit of resource-poor farmers. The Programme therefore set out to catalyse interactions between the various players who are needed to bridge the gap between strategic research in advanced labs and resource-poor farmers.

GCP and EMBRAPA were both working towards tangible applied outcomes, says Claudia: “GCP was not only giving you money, they are really serious about what are you doing: ‘Did you deliver everything you promised?’”

Claudia delivered. She and her team at EMBRAPA were able to find an important aluminium-tolerance gene in maize similar to the sorghum gene. This outcome provided the basic materials for molecular-breeding programmes focusing on improving maize production and stability on acidic soils in Africa and other developing regions.

Photo: L Kochian

Maize trials in the field at EMBRAPA. The maize plants on the left are aluminium-tolerant while those on the right are not.

Multifaceted and tangible results

Through further GCP funding, EMBRAPA researchers Robert Schaffert and Sidney Parentoni were able to work together with two researchers from Kenya, Dickson Ligeyo and Samuel Gudu, to develop a breeding programme to combine the improved Brazilian germplasm with locally adapted Kenyan materials. A new base of improved germplasm was established for Kenyan breeders, which allowed the development of varieties adapted to acidic soils in Kenya.

Sidney, a maize breeder for GCP projects and now the deputy head of research and development for EMBRAPA Maize & Sorghum, says that the benefits of being part of GCP are multifaceted: “It was very important, not only for EMBRAPA as an institute, but also individually for each of the participants that had the opportunity to interact with partners in different parts of the word,” says Sidney.

Photo: Bioversity International

A Kenyan farmer with her sorghum crop.

“Each of them adds a piece to build the results achieved by GCP, which from my perspective promoted a number of advances in the areas of genetics and breeding.

“Technologies such as root image scanning developed at Cornell [University] were transferred to EMBRAPA and allowed us to do large-scale screening in a number of maize and sorghum genotypes with large impacts in phosphorous-efficiency studies.

“Scientists from Africa were trained in breeding and screening techniques at EMBRAPA, and Brazilian scientists had the opportunity to go to Africa and interact with African researchers to jointly develop strategies for breeding maize and sorghum for low-phosphorous and acidic soils.

“These trainings and exchanges of experiences were very important for the people and for the institutions involved,” says Sidney.

Sustainable partnerships to break ground for groundnut

Photo: N Palmer/CIAT

Groundnut

Soraya Leal-Bertioli is a researcher in the EMBRAPA Genetic Resources & Biotechnology centre. She works on groundnut (also known as peanut), and formed part of the GCP team working on groundnut with tolerance to drought and resistance to diseases and fungal contamination. She concurs that GCP united researchers from all over the globe in a common goal.

“GCP not only identified groups, but it went out, searched for people and invited contributions, offered resources to get them together. GCP brought partnerships to a whole new level,” Soraya says.

“Last time I checked there were 200 partners in 50 countries. No one is able to do that. It required a lot of money, a lot of resources, but the way it was dealt with in GCP was: ‘Let’s reach out for the main players, the ones who have the technology, and also the ones who can use the technology’.

“GCP used the resources for the benefit of the community and brought everybody together.”

Soraya says the traditional way of funding research often had ‘no structure’.

“Sometimes a university or funding body receives a large amount of money and decides to build something, a new institute in the middle of the jungle somewhere, but they don’t have anybody to run it; it is not sustainable.

“What GCP did was help to provide the structure and the agents for the whole system. They helped train the people to run the whole system. This is a very sustainable model, which is very likely to give good results in a much shorter time frame than other programmes.”

Watch Soraya – and other members of the team – discuss the complex personality of groundnut and groundnut research in our video series:

Genetic stocks AND people are products

The products and outcomes of the collaboration with GCP have included both the tangible and the not-so-tangible. Sidney says that a large quantity of Brazilian improved maize and sorghum lines tolerant to acidic soils has been developed over the years at EMBRAPA.

“These materials were shared with partners in Africa, and this was a major contribution to Kenyan farmers, as part of this collaborative work done in the scope of GCP.

“To be part of the programme has been very important for EMBRAPA’s research team. It has given us the opportunity to interact with a diversity of institutes.”

Sidney mentions institutes they gave worked with through GCP, including Cornell University and Texas A&M University in the US, the Japan International Research Center for Agricultural Sciences (JIRCAS), the International Rice Research Institute (IRRI), the International Maize and Wheat Improvement Center (CIMMYT), and various institutes in Africa, such as Moi University, Kenya, and the Kenya Agricultural and Livestock Research Organisation (KALRO).

Sidney concludes: “In this large network of partnerships, EMBRAPA was able to learn and to share information in a highly productive way.

“From my perspective, the involvement with GCP projects allowed me to grow as a researcher and as a person, and also at the same time to share and to acquire new knowledge in a number of areas. I think it was a ‘win-win’ interaction for all the participants.”

Many of the products generated within the scope of GCP, such as markers and germplasm, are already available within EMBRAPA’s breeding programmes. Avenues for further research have been paved based on the GCP achievements, and these new research lines will be continued within new projects.

As Claudia says: “The strong partnerships built along the way with GCP will be maintained by us joining with new research teams from other institutes and countries to work on new projects.”

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