Peer review

Abiotic stresses that affect wheat production?heat (H) and drought (D)?often occur concurrently. The genetic dissection of stress tolerance in a population with large range of phenology is difficult due to the confounding effects. We developed a recombinant inbred line (RIL) population of 276 entries with a narrow range of phenology, from a cross between a synthetic-derived parent (SYN-D: Croc 1/Aegilops squarrosa (224)//Opata) and an elite line (Weebill 1) to (a) understand the individual and combined effects of H and D stresses on yield and related traits, (b) identify the genetic basis of individual and combined stress tolerance, and (c) know the genetics of stress tolerance that can be explored from the line SYN-D. Phenotypic analysis indicated that the detrimental effect of combined stresses was greater than their individual effects. We constructed a genetic map?2771.5 cM?of the population with 569 SNPs (231 DArTseq and 338 Illumina bead chip 90 K array) and identified 71 QTLs, in which eight were common among stresses. We identified five QTL hotspots for yield and related traits under D, H, and H + D in chromosomes 2A (20.5 to 30.5 cM), 3D (92.5 to 108.5 cM), 6D (68.5 to 73.5 cM), 6D (125.5 to 135.5 cM), and 7B (40.5 to 61.5 cM). Among the 71 identified QTLs, SYN-D contributed 37 QTLs (52%) and Weebill 1 contributed 34 QTLs (48%). SYN-D also contributed the common thousand-grain weight QTL detected under H, D, and H + D, which can be used in molecular-assisted breeding.

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