Table_1_Mining Aegilops tauschii genetic diversity in the background of bread wheat revealed a novel QTL for seed dormancy.xlsx

Due to the low genetic diversity in the current wheat germplasm, gene mining from wild relatives is essential to develop new wheat cultivars that are more resilient to the changing climate. Aegilops tauschii, the D-genome donor of bread wheat, is a great gene source for wheat breeding; however, identifying suitable genes from Ae. tauschii is challenging due to the different morphology and the wide intra-specific variation within the species. In this study, we developed a platform for the systematic evaluation of Ae. tauschii traits in the background of the hexaploid wheat cultivar ‘Norin 61’ and thus for the identification of QTLs and genes. To validate our platform, we analyzed the seed dormancy trait that confers resistance to preharvest sprouting. We used a multiple synthetic derivative (MSD) population containing a genetic diversity of 43 Ae. tauschii accessions representing the full range of the species. Our results showed that only nine accessions in the population provided seed dormancy, and KU-2039 from Afghanistan had the highest level of seed dormancy. Therefore, 166 backcross inbred lines (BILs) were developed by crossing the synthetic wheat derived from KU-2039 with ‘Norin 61’ as the recurrent parent. The QTL mapping revealed one novel QTL, Qsd.alrc.5D, associated with dormancy explaining 41.7% of the phenotypic variation and other five unstable QTLs, two of which have already been reported. The Qsd.alrc.5D, identified for the first time within the natural variation of wheat, would be a valuable contribution to breeding after appropriate validation. The proposed platform that used the MSD population derived from the diverse Ae. tauschii gene pool and recombinant inbred lines proved to be a valuable platform for mining new and important QTLs or alleles, such as the novel seed dormancy QTL identified here. Likewise, such a platform harboring genetic diversity from wheat wild relatives could be a useful source for mining agronomically important traits, especially in the era of climate change and the narrow genetic diversity within the current wheat germplasm.

鉴于当前小麦种质资源遗传多样性匮乏，从野生近缘种中挖掘功能基因，对于培育更能适应气候变化的小麦新品种至关重要。节节麦（Aegilops tauschii）作为面包小麦的D基因组供体，是小麦育种的优质基因源；然而，由于该物种形态分化显著且种内变异广泛，从节节麦中筛选适宜育种的基因颇具挑战。本研究以六倍体小麦品种‘Norin 61’为遗传背景，构建了一套可系统评价节节麦性状的研究平台，以此实现数量性状位点（Quantitative Trait Locus, QTL）定位与功能基因挖掘。为验证该平台的可靠性，我们针对与穗发芽抗性相关的种子休眠性状开展了分析。本研究使用了包含43份节节麦材料的多合成衍生系（Multiple Synthetic Derivative, MSD）群体，该群体覆盖了节节麦全物种范围的遗传多样性。结果显示，群体中仅9份材料具有种子休眠特性，其中来自阿富汗的KU-2039种子休眠水平最高。我们以源自KU-2039的合成小麦为供体亲本，以‘Norin 61’为轮回亲本，构建了包含166个回交自交系（Backcross Inbred Lines, BILs）的遗传群体。通过QTL定位分析，我们鉴定到1个新的休眠相关QTL：Qsd.alrc.5D，其可解释41.7%的表型变异；同时还检测到5个不稳定QTL，其中2个已有文献报道。本次在小麦自然变异中首次发现的Qsd.alrc.5D，经进一步验证后可应用于小麦育种实践，具有重要的应用价值。本研究所采用的、基于多样节节麦基因库构建的MSD群体与回交自交系平台，可有效挖掘新的重要QTL或等位基因，正如本研究中鉴定到的新型种子休眠QTL。同样，这类搭载小麦野生近缘种遗传多样性的研究平台，可用于挖掘农艺重要性状，在当前小麦种质遗传基础狭窄、气候变化加剧的时代尤为关键。