Abstract
Understanding of the genetic mechanism of heat tolerance (HT) can accelerate and improve wheat breeding in dealing with a warming climate. This study identified and validated quantitative trait loci (QTL) responsible for HT in common wheat. The International Triticeae Mapping Initiative (ITMI) population, recombinant inbreed lines (RILs) derived from a cross between Synthetic W7984 and Opata M85, was phenotyped for shoot length, root length, whole plant length under heat stress and corresponding damage indices (DIs) to compare HT performances of individuals. Wide variations among the RILs were shown for all the traits. A total of 13 QTL including 9 major QTL and 4 minor QTL were identified, distributed on 6 wheat chromosomes. The six major QTL with the highest R2 were associated with different traits under heat stress. They were all from Opata M85 background and located within a 2.2 cm interval on chromosome 4D, making up a QTL hotspot conferring HT in common wheat. The QTL hotspot was validated by genotyping-phenotyping association analysis using single-nucleotide-polymorphism (SNP) assays. The QTL, especially the 4D QTL hotspot identified and validated in this study, are valuable for the further fine mapping and identification of key genes and exploring genetic mechanism of HT in wheat.
Highlights
Heat has become a serious constraint for wheat production with global climate change [1]
Some reports indicated that some particular quantitative trait loci (QTL) at seedling stage and reproductive stage were collocated on the same chromosomes [13], and some well-known heat-induced genes at reproductive stage were found significantly enhanced in acetylation levels in wheat seedlings [14]
This study identified QTL conferring heat tolerance (HT) at the seedling stage in common wheat based on root, shoot, whole plant length and their corresponding damage indices (DIs)
Summary
Heat has become a serious constraint for wheat production with global climate change [1]. Heat stress may affect harvest and yield and grain quality [4]. Though reproductive stage is most sensitive for final yield and the most studied stage [5], heat damage may happen during different growth and developmental stages in the crop including seedling stage [6]. Heat tolerance (HT) in plants is a quantitative trait involving complex genetic, physiological, and biochemical controls and is affected by environmental factors. Grain yield is significantly correlated with seedling traits such as root length and shoot length [8]. In response to heat stress, heat shock proteins play important roles at both seedling and reproductive stages [12]. QTL identification and validation for seedling stage may help us to understand the mechanism of heat tolerance at different stages
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