预计到本世纪末,全球环境温度将上升3-5°C,在关键的作物生长阶段,以及不可预测的热浪,会大幅降低粮食产量,并将对粮食安全构成巨大挑战。因此,确定能够承受高温的小麦遗传资源非常重要,发现支撑对较高温度的韧性的基因,并将这些遗传资源用于小麦育种,以开发耐热品种。在这项研究中,在三个地点(伊斯兰堡,巴哈瓦尔布尔,和TandoJam),并收集了11个形态和产量相关性状的数据。用50KSNP阵列对多样性小组进行基因分型,以进行全基因组关联研究(GWAS)以研究SHW的耐热性。已知的耐热轨迹,对TaHST1进行了分析,以鉴定SHW中该基因座的不同单倍型及其与SHW中谷物产量和相关性状的关联。谷物产量(GY)下降了36%,千粒重(TKW)减少23%,由于热应激条件,种群中三个位置的每穗谷物(GpS)减少了18%。GWAS鉴定了分布在SHW中所有21条染色体上的143个定量性状核苷酸(QTNs)。在这些中,52个QTNs与热胁迫下的形态和产量相关性状相关,而其中15个与多个性状相关。然后将小麦基因组的热休克蛋白(HSP)框架与本研究中鉴定的QTNs进行比对。chr2B上有17个QTNs接近HSP,chr3D,chr5A,chr5B,chr6D,和chr7D。D基因组上的QTNs和邻近HSP的QTNs可能携带耐热基因的新等位基因。TaHST1的分析表明,该基因座的SHW中存在15个单倍型,而hap1显示最高频率为25%(33SHWs)。这些单倍型与SHW中的产量相关性状显着相关。SHW中与产量相关性状相关的新等位基因可能是育种部署的绝佳库。
The projected rise in global ambient temperature by 3-5 °C by the end of this century, along with unpredicted heat waves during critical crop growth stages, can drastically reduce grain yield and will pose a great food security challenge. It is therefore important to identify wheat genetic resources able to withstand high temperatures, discover genes underpinning resilience to higher temperatures, and deploy such genetic resources in wheat breeding to develop heat-tolerant cultivars. In this study, 180 accessions of synthetic hexaploid wheats (SHWs) were evaluated under normal and late wheat growing seasons (to expose them to higher temperatures) at three locations (Islamabad, Bahawalpur, and Tando Jam), and data were collected on 11 morphological and yield-related traits. The diversity panel was genotyped with a 50 K SNP array to conduct genome-wide association studies (GWASs) for heat tolerance in SHW. A known heat-tolerance locus, TaHST1, was profiled to identify different haplotypes of this locus in SHWs and their association with grain yield and related traits in SHWs. There was a 36% decrease in grain yield (GY), a 23% decrease in thousand-grain weight (TKW), and an 18% decrease in grains per spike (GpS) across three locations in the population due to the heat stress conditions. GWASs identified 143 quantitative trait nucleotides (QTNs) distributed over all 21 chromosomes in the SHWs. Out of these, 52 QTNs were associated with morphological and yield-related traits under heat stress, while 15 of them were pleiotropically associated with multiple traits. The heat shock protein (HSP) framework of the wheat genome was then aligned with the QTNs identified in this study. Seventeen QTNs were in proximity to HSPs on chr2B, chr3D, chr5A, chr5B, chr6D, and chr7D. It is likely that QTNs on the D genome and those in proximity to HSPs may carry novel alleles for heat-tolerance genes. The analysis of TaHST1 indicated that 15 haplotypes were present in the SHWs for this locus, while hap1 showed the highest frequency of 25% (33 SHWs). These haplotypes were significantly associated with yield-related traits in the SHWs. New alleles associated with yield-related traits in SHWs could be an excellent reservoir for breeding deployment.