Mapping quantitative trait loci associated with stripe rust resistance from the Canadian wheat cultivar ‘AAC Innova’

Stripe rust, caused by <i>Puccinia striiformis</i> Westend. f.sp. <i>tritici</i> Erikss. (<i>Pst</i>), is one of the most devastating diseases of wheat (<i>Triticum aestivum</i> L.) globally. Exploring and utilizing new sources of resistance is essential for breeding resistant wheat cultivars. Thus, a doubled haploid population (n = 291) derived from the cross ‘AAC Innova’/‘AAC Proclaim’ was evaluated to dissect the genetics of resistance in the cultivar ‘AAC Innova’. This population was evaluated for stripe rust severity in disease nurseries at Creston, British Columbia (in 2016 and 2020), and Lethbridge, Alberta (in 2016, 2017 and 2020), and genotyped using the wheat 90 K SNP assay. A high-density genetic map was constructed which consisted of 7112 SNP markers with an average marker interval of 2.3 cM. Quantitative trait loci (QTL) mapping identified one major (<i>QYr.lrdc-2A</i>) and 10 minor effect (<i>QYr.lrdc-2B.1, QYr.lrdc-2B.2, QYr.lrdc-2B.3, QYr.lrdc-2B.4, QYr.lrdc-2D, QYr.lrdc-3B, QYr.lrdc-5A, QYr.lrdc-5B, QYr.lrdc-5D</i> and <i>QYr.lrdc-7D</i>) loci. The QTL <i>QYr.lrdc-2A</i> was consistently effective against <i>Pst</i> races across all environments and explained up to 33.0% of the phenotypic variation. Other QTLs were either less consistent or environment specific. ‘AAC Innova’ contributed stripe rust resistance alleles for most of the QTLs except for <i>QYr.lrdc-2D, QYr.lrdc-5A and QYr.lrdc-7D</i>. The QTLs identified in this study should be valuable for diversifying the sources of genetic resistance against current and new virulent races of <i>Pst</i>. In particular, the ‘AAC Innova’-derived QTL <i>QYr.lrdc-2A</i> could be a valuable source of resistance to incorporate into commercial cultivars and combine with other genes using the associated SNP markers identified in this study.

由条形柄锈菌小麦专化型（*Puccinia striiformis* Westend. f.sp. *tritici* Erikss.，简称Pst）引起的小麦条锈病，是全球范围内危害普通小麦（*Triticum aestivum* L.）最严重的病害之一。发掘并利用新的抗源对抗病小麦品种选育至关重要。为此，本研究针对杂交组合‘AAC Innova’/‘AAC Proclaim’构建的双单倍体群体（doubled haploid population，n=291）展开分析，以解析品种‘AAC Innova’的抗病遗传机制。
该群体分别于不列颠哥伦比亚省克雷斯顿市（2016年、2020年）和阿尔伯塔省莱斯布里奇市（2016年、2017年、2020年）的病圃中开展条锈病病情鉴定，并利用小麦90K单核苷酸多态性（SNP）分型芯片进行基因型鉴定。
本研究构建了一张包含7112个SNP标记、平均标记间距为2.3 cM的高密度遗传连锁图谱。通过数量性状位点（quantitative trait loci，QTL）定位，共检测到1个主效QTL（*QYr.lrdc-2A*）及10个微效QTL（*QYr.lrdc-2B.1*、*QYr.lrdc-2B.2*、*QYr.lrdc-2B.3*、*QYr.lrdc-2B.4*、*QYr.lrdc-2D*、*QYr.lrdc-3B*、*QYr.lrdc-5A*、*QYr.lrdc-5B*、*QYr.lrdc-5D*及*QYr.lrdc-7D*）。
主效QTL *QYr.lrdc-2A*在所有供试环境中均对Pst小种表现稳定抗性，可解释最高达33.0%的表型变异；其余QTL的抗性稳定性较差或仅具有环境特异性。除*QYr.lrdc-2D*、*QYr.lrdc-5A*及*QYr.lrdc-7D*外，‘AAC Innova’为其余多数QTL贡献了抗病等位基因。
本研究鉴定到的QTL可为丰富当前及未来Pst毒性小种的遗传抗源多样性提供重要支撑。其中，源自‘AAC Innova’的主效QTL *QYr.lrdc-2A*可通过本研究关联的SNP标记，用于商业化小麦品种的抗病性状改良及与其他抗病基因的聚合育种。