Identification of quantitative trait loci and candidate genes underlying kernel traits of wheat (Triticum aestivum L.) in response to drought stress

Kernel traits are the most important yield components in wheat. The use of genetic loci and candidate genes that respond to drought stress without yield loss improves the productivity of wheat in arid regions. In this study, the 90K iSelect Infinium SNP assay for wheat was used to generate a high-density genetic map and identify quantitative trait loci (QTL) for kernel traits in a set of recombinant inbred lines (RILs). A total of 85 additive QTLs, including 16 for thousand-kernel weight (TKW), 14 for kernel length (KL), 16 for kernel width (KW), 11 for kernel thickness (KT), 18 for kernel size (KS), and 10 for kernel diameter ratio (KDR), were detected under drought stressed and well-watered conditions. Among them, 12 QTLs were identified as environmentally stable QTLs and refined into 10 QTL clusters, in which a total of 3738 candidate genes were extracted from the confidence interval of these QTL clusters. We discovered a QTL cluster interval (C3) on chromosome 5A, in which we found a potential candidate gene TraesCS5A02G288000 ( TaCYP71E1-5A ) for KS and KL and was annotated as “cytochrome P450”. The KASP marker for TaCYP71E1-5A was developed and further validated in 220 wheat varieties. These results provide a useful insight into the genetic factors underlying the kernel traits response to drought stress and will thus facilitate the improvement of wheat productivity under drought stress conditions in breeding programs.