Details for Mapping QTL for heat tolerance at grain filling stage in common wheat

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.

 Full article