Heat stress (HS) causes substantial damages to worldwide crop production. As a cool season crop, wheat (Triticum aestivum) is sensitive to HS-induced damages. To support the genetic improvement of wheat HS tolerance (HST), we conducted fine mapping of TaHST1, a locus required for maintaining wheat vegetative and reproductive growth under elevated temperatures. TaHST1 was mapped to the distal terminus of 4AL chromosome arm using genetic populations derived from two BC₆F₆ breeding lines showing tolerance (E6015-4T) or sensitivity (E6015-3S) to HS. The 4AL region carrying TaHST1 locus was approximately 0.949 Mbp and contained the last 19 high confidence genes of 4AL according to wheat reference genome sequence. Resequencing of E6015-3S and E6015-4T and haplotype analysis of 3087 worldwide wheat accessions revealed heightened deletion polymorphisms in the distal 0.949 Mbp region of 4AL, which was confirmed by the finding of frequent gene losses in this region in eight genome-sequenced hexaploid wheat cultivars. The great majority (86.36%) of the 3087 lines displayed different degrees of nucleotide sequence deletions, with only 13.64% of them resembling E6015-4T in this region. These deletions can impair the presence and/or function of TaHST1 and surrounding genes, thus rendering global wheat germplasm vulnerable to HS or other environmental adversities. Therefore, conscientious and urgent efforts are needed in global wheat breeding programmes to optimize the structure and function of 4AL distal terminus by ensuring the presence of TaHST1 and surrounding genes. The new information reported here will help to accelerate the ongoing global efforts in improving wheat HST.

中文翻译：

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4AL染色体臂末端缺失的增加会削弱小麦的耐热性

热胁迫（HS）对全世界的农作物产量造成重大损害。作为凉爽季节的作物，小麦（Triticum aestivum）对HS诱导的伤害很敏感。为了支持小麦HS耐性（HST）的遗传改良，我们对TaHST1进行了精细定位，TaHST1是在高温下维持小麦营养和生殖生长所必需的基因座。使用来自两个BC ₆ F ₆育种系的遗传种群，将TaHST1映射到4AL染色体臂的末端，该种群显示出对HS的耐受性（E6015-4T）或敏感性（E6015-3S）。携带TaHST1的4AL地区根据小麦参考基因组序列，基因座大约为0.949 Mbp，并包含最后19个4AL的高信度基因。对E6015-3S和E6015-4T的重新测序以及对3087个全球小麦种质的单倍型分析显示，在4AL的0.949 Mbp远端区域中缺失多态性增强，这一发现已通过在八个基因组测序的六倍体小麦中频繁出现的基因缺失而得到证实。品种。3087个系中的绝大多数（86.36％）显示出不同程度的核苷酸序列缺失，其中只有13.64％与该区域的E6015-4T类似。这些删除可能损害TaHST1的存在和/或功能。和周围的基因，从而使全球小麦种质易受HS或其他环境逆境侵害。因此，在全球小麦育种计划中需要做出认真而紧急的努力，以通过确保TaHST1和周围基因的存在来优化4AL末端的结构和功能。此处报道的新信息将有助于加速全球正在进行的改善小麦HST的努力。