QTL Analysis for Grain Failing Rate and Related Traits in Doubled Haploid Population of Wheat Under Heat Stress Conditions

Doubled haploid (DH) population (Yecora Rojo X Ksu106) developed from a cross of a high-quality, heat-sensitive wheat cultivar (Yecora Rojo) and an adapted Saudi wheat line characterized by poor bread making quality, heat tolerance and high yield potential (Ksu106) was used to identify molecular markers linked to a wheat (Triticum aestivum L.) grain failing rate and related traits under heat stress conditions. The parents and 100 DH were evaluated phenotypically for heat tolerance at two locations. 800 simple sequence repeat (SSR) primers were tested for polymorphism among the parental genotypes and the DH lines. Composite interval mapping detected 34 QTLs for grain failing rate and related traits under heat stress conditions. These QTLs were distributed over all 21 wheat chromosomes except 3A, 4A, 6A, 7A, 4B and 4D, and they explained 6– 48 % of the phenotypic variation for the individual traits. Of these QTLs, 24 QTLs explained phenotypic variation over 20 %, and two were detected in both locations. One notable tow QTLs for grain falling rate on chromosome 1D and 3B at Riyadh location were detected in both environments (normal condition and heat stress condition), and accounted over 20% of phenotypic variation. All of the QTLs for grain failing rate and related traits had a positive additive effect indicating contribution of alleles increasing the traits by the tolerant parent Ksu106. In addition, the positive additive effects indicated the relative importance of additive gene effects in controlling the traits for heat tolerance in DH lines. Therefore, these markers linked to QTLs for the grain failing rate and related traits under heat stress conditions can be further used in breeding for heat tolerance in wheat.