Dignat G, Welcker C, Sawkins M, Ribaut JM and Tardieu F (2013). The growths of leaves, shoots, roots and reproductive organs partly share their genetic control in maize plants. Plant, Cell & Environment Printed online 7 January 2013. (DOI: 10.1111/pce.12045). (G3005.15). Not open access: view abstract

Bandillo N, Raghavan C, Muyco PA, Sevilla MAL, Lobina IT, Dilla-Ermita CJ,  Tung C-w, McCouch S, Thomson M, Mauleon R, Singh RK, Gregorio G, Redoña E and Leung H (2013). Multi-parent advanced generation inter-cross (MAGIC) populations in rice: progress and potential for genetics research and breeding. Rice 2013, 6:11.

This article describes the development of Multi-parent Advanced Generation Inter-Cross populations (MAGIC) in rice and discusses potential applications for mapping quantitative trait loci (QTLs) and for rice varietal development. We have developed 4 multi-parent populations: indica MAGIC (8 indica parents); MAGIC plus (8 indica parents with two additional rounds of 8-way F1 inter-crossing); japonica MAGIC (8 japonica parents); and Global MAGIC (16 parents – 8 indica and 8 japonica). The parents used in creating these populations are improved varieties with desirable traits for biotic and abiotic stress tolerance, yield, and grain quality. The purpose is to fine map QTLs for multiple traits and to directly and indirectly use the highly recombined lines in breeding programs. These MAGIC populations provide a useful germplasm resource with diverse allelic combinations to be exploited by the rice community.

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Okono A, Monneveux P and Ribaut J-M (2013). Facing the challenges of global agriculture today: what can we do about drought? Frontiers in Plant Physiology 4:289. (DOI: 10.3389/fphys.2013.00289).

It is estimated that the planet's demand for food and feed crops will almost double by 2050 (Foley et al., 2011). Globally, rainfed agriculture is practised in 80% of the total agricultural area and generates 62% of the world's staple food (FAOSTAT, 2011). Taking into consideration global water scarcity and increases in demand for non-agricultural uses of water, expansion of the area under irrigation in developing countries does not appear to be a realistic scenario to address the challenge of food security.

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Varshney RK, Gaur PM, Chamarthi SK, Krishnamurthy L, Tripathi S, Kashiwagi J, Samineni S, Singh VK, Thudi M, Jaganathan D (2013). Fast-track introgression of “QTL-hotspot” for root traits and other drought tolerance traits in JG 11, an elite and leading variety of chickpea. The Plant Genome 6(3). (DOI: 10.3835/plantgenome2013.07.0022).

A “QTL-hotspot” containing quantitative trait loci (QTL) for several root and drought tolerance traits was transferred through marker-assisted backcrossing into JG 11, a leading variety of chickpea (Cicer arietinum L.) in India from the donor parent ICC 4958. Foreground selection with up to three simple sequence repeat markers, namely TAA170, ICCM0249, and STMS11, and background selection with up to 10 amplified fragment length polymorphism primer combinations was undertaken. After undertaking three backcrosses with foreground and background selection and selfing, 29 BC3F2 plants homozygous for two markers (ICCM0249 and TAA170) were selected and referred as introgression lines (ILs).

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Li S-P, Chang X-P, Wang C-S and Jing R-L (2013). Mapping QTL for heat tolerance at grain filling stage in common wheat. Scientia Agricultura Sinica 46(10):2119–2129 (DOI: 10.3864/j.issn.0578-1752.2013.10.018). Article in Chinese with abstract in English. (G7010.02.01)

Abstract: Objective In this study, a doubled haploid (DH) population with 150 lines, which was derived from the cross of two Chinese common wheat cultivars Hanxuan 10 and Lumai 14, was used as the plant material to identify the heat tolerance index (HTI) for related physiological traits and thousand-grain weight (TGW) at grain filling stage in common wheat and carry out quantitative trait loci (QTL) analysis. The purpose was to identify the essential QTL with stable and remarkable effects and find a theoretical basis on marker-assisted selection for improving the heat tolerance in wheat breeding program.

Method The mixed-model-based composite interval mapping method was employed to identify QTL for HTI of related traits in two soil moisture environments.

Result A total of 12 additive QTL and 17 epistatic QTL for HTI of TGW and physiological traits related to heat tolerance were located on all chromosomes except 1D, 6D and 7B under two soil moisture conditions. One single additive QTL can explain 2.64%-11.41% phenotypic variance for HTI, and a pair of epistatic QTL can explain 2.45%-8.84% phenotypic variance for HTI. Nine of 12 additive QTL have interaction effects with the environments, and the interaction effect of single additive QTL with the environment can explain 1.41%-4.66% phenotypic variance for HTI. Only 5 of the 17 epistatic QTL exist interaction effects with the environments, and the interaction effect of single pair of QTL with the environment can explain 0.62%-2.32% phenotypic variance for HTI. The allelic contribution to the HTI QTL came from both parents. Some DH lines were more tolerant to the heat stress than their parents.

Conclusion To evaluate the heat tolerance at grain filling stage, the HTI for TGW is a direct criteria, the following two physiological index are indirect criteria, i.e. the HTI for flag leaves relative water content (IRWC) is an available index under rainfed condition, and the HTI for canopy temperature depression (ICTD) is suitable under well-watered condition. The QTL for HTIs mainly distribute on the chromosomes 1B, 2D, 5A, 5B, 6A, 6B and 7A, showing that these chromosomes have close relationship with heat-tolerance at grain filling stage. The genetic effects of QTL for TGW HTI and chlorophyll content (CC) mainly are additive effect, and that of CTD and chlorophyll fluorescence parameters (CFP) are mainly epistatic effect. The additive effect and the epistatic effect are almost equal in the genetic effect of the QTL for the RWC HTI.

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Peprah BB, Ofori K, Asante IK, Parkes E (2013). Genetic variability of three cassava traits across three locations in Ghana. African Journal of Plant Science 7(7):265–267 (DOI:10.5897/AJPS12.058). (G7010.01.05).

A study was conducted to assess the extent of genetic variability, broad-sense heritability and correlations for fresh root weight, root number and top weight of five cassava genotypes across three locations in 2 years. Combined analysis of variance revealed highly significant genotypic effect for all the traits. Genotype x environment interaction was also significant for all the traits studied indicating considerable but, varying response of the genotypes to the environments. High broad-sense heritability and genetic advance as percent of the mean were observed for fresh root weight, suggesting that the trait is primarily under genetic control and that a simple recurrent phenotypic selection scheme would be rewarding. Phenotypic coefficients of variation values were larger than their corresponding genotypic coefficient of variation values for all traits. Correlations between the three traits were highly significant and positive indicating that simultaneous progress for the three traits is feasible.

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Chai Y, Li X, Zhao Z, Sun L, Li Y and Jing L (2013). Diversity analysis of agronomic and quality characters of foreign wheat germplasm resources. Journal of Agriculture 3(9):1–8. Article in Chinese with abstract in English. (G7010.02.01)

Abstract: In order to gain knowledge of genetic diversity of wheat and improve their usage efficiency as germplasm resource. Diversities of agronomic and quality characters were analyzed for 146 foreign wheat germplasm in the field in southern Shanxi Province, basing on the data statistic analysis, principal component and cluster analysis methods. The average coefficient of variance was 10.9%, and the average diversity index was 1.4 with 18 wheat characters. It was-to seed yield, spike length, kernels per spike, spikes per plant, 1000-grain weight, stability time, tensile area, maximum resistance, sedimentation value and development time. Principal component and cluster analysis were used to 31 high-yield germplasm resources. The additive contributing rate of first eight principal components was 92.73%, eight major discriminating characteristics were selected to reflect the comprehensive economic characters and quality characters. According to the genetic distance, 31 germplasm resources were divided into 7 groups. Each group had different characteristics and showed abundant genetic diversity in agronomic and quality characters.

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Chai Y, Li X, Zhao Z, Sun L, Li Y and Ma G (2013). Identification and hybridization usage of CIMMYT wheat germplasms. Chinese Agricultural Science Bulletin 29(33):56–61. Article in Chinese with abstract in English. (G7010.02.01)

Abstract: In order to improve wheat germplasm diversity, increase wheat yield and quality, agronomic and quality characters were evaluated for 145 foreign wheat germplasms in the field in southern Shanxi Province. The results showed that, these germplasms were weak vernal wheat, which might be sown on late Oct. as germplasm use in southern Shanxi Province. The coefficients of variance of spikes per plant, kernels per spike, 1000-grain weight and yield were 15.7%, 16.03%, 12.23% and 23.96% respectively. Most of the germplasms had better intergrated traits, especially in seed gluten. Agronomic traits had greater genetic diversity. Plant height and 1000-grain weight had significantly correlation with yield. Thirty-two germplasms yielded more than 3750 kg/hm2. We selected 8 trong gluten wheat germplasms and 35 better intergrated traits germplasms which had large spike, spikelets with many kernels as key germplasms for breeding. We adjusted the sowing date to meet flowering of these materials for hybridization with good local strains and produced abundant F₃, BCF₂ and BC₁F₁ generation. New drought-tolerance materials and strains with large spike and high yielding may be selected from the CIMMYT generations.

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Eisenstein M.(2013). Plant breeding: Discovery in a dry spell. Nature 501: S7–S9. Published online 25 September 2013. (DOI:10.1038/501S7a). Not open access: view online

Wang S-G, Li Z-Q, Jia S-S, Sun D-Z, Shi Y-G, Fan H, Liang Z-H and Jing R-L (2013). Relationships of wheat leaf stomatal traits with wheat yield and drought resistance. Chinese Journal of Applied Ecology 24(6):1609−1614. (G7010.02.01)

Abstract: Taking the DH population of wheat cultivar Hanxuan10/Lumai14 as test object, and by the methods of correlation analysis and path analysis, this paper studied the relationships of the flag leaf stomatal density (SD), stomatal length and width (SL and SW), stomatal conductance (g_s), photosynthetic rate (P_n), and transpiration rate (T_r) on the 10th and 20th day after anthesis with the yield and the index of drought-resistance under the conditions of drought stress and normal irrigation. Under the two conditions, most of the test leaf traits on the 10th day after anthesis had less correlation with the yield and the index of drought-resistance, whereas the leaf traits on the 20th day after anthesis had significant positive correlations with thousand kernel weight  but less correlation with grain number per ear, grain yield per plant, and index of drought-resistance. Path analysis showed that g_s, P_n, and T_r were the main factors affecting the grain yield per plant (YPP) and the index of drought resistance (IDR), and the effects were stronger both in direct and in indirect ways. The direct and indirect effects of SD, SL, and SW on the YPP and IDR were lesser. Under both drought stress and normal irrigation, and on the 10th and 20th day after anthesis, there were significant correlations between SD and SL, and between SL and SW, g_s, P_n, and T_r, but the correlations of SD and SL with g_s, P_n, and T_r changed with water condition or growth stage. Therefore, it would be not always a good means to select the leaf stomatal density and size as the targets for breeding to improve the leaf stomatal conductance, photosynthetic rate, and transpiration rate, and further, to promote the yield.

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