Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA.
International Maize and Wheat Improvement Center (CIMMYT), Mexico, DF, Mexico.
Plant Genome. 2021 Jul;14(2):e20105. doi: 10.1002/tpg2.20105. Epub 2021 Jun 19.
Many of the major stem rust resistance genes deployed in commercial wheat (Triticum spp.) cultivars and breeding lines become ineffective over time because of the continuous emergence of virulent races. A genome-wide association study (GWAS) was conducted using 26,439 single nucleotide polymorphism (SNP) markers and 280 durum wheat [Triticum turgidum L. subsp. Durum (Desf.) Husnot] lines from CIMMYT to identify genomic regions associated with seedling resistance to races TTKSK, TKTTF, JRCQC, and TTRTF and field resistance to TKTTF and JRCQC. The phenotypic data analysis across environments revealed 61-91 and 59-77% of phenotypic variation was explained by the genotypic component for seedling and adult plant response of lines, respectively. For seedling resistance, mixed linear model (MLM) identified eight novel and nine previously reported quantitative trait loci (QTL) while a fixed and random model circulating probability unification (FarmCPU) detected 12 novel and eight previously reported QTL. For field resistance, MLM identified 12 novel and seven previously reported loci while FarmCPU identified seven novel and nine previously reported loci. The regions of Sr7a, Sr8155B1, Sr11, alleles of Sr13, Sr17, Sr22/Sr25, and Sr49 were identified. Novel loci on chromosomes 3B, 4A, 6A, 6B, 7A, and 7B could be used as sources of resistance to the races virulent on durum wheat. Two large-effect markers on chromosome 6A could potentially be used to differentiate resistant haplotypes of Sr13 (R1 and R3). Allelism tests for Sr13, breaking the deleterious effect associated with Sr22/Sr25 and retaining the resistance allele at the Sr49 locus, are needed to protect future varieties from emerging races.
许多在商业小麦（Triticum spp.）品种和品系中使用的主要茎锈病抗性基因，由于毒性菌株的不断出现，随着时间的推移而变得无效。利用来自 CIMMYT 的 26439 个单核苷酸多态性（SNP）标记和 280 个硬粒小麦（Triticum turgidum L. subsp. Durum（Desf.）Husnot）品系进行了全基因组关联研究（GWAS），以鉴定与幼苗对 TTKSK、TKTTF、JRCQC 和 TTRTF 菌株以及大田对 TKTTF 和 JRCQC 菌株的抗性相关的基因组区域。跨环境的表型数据分析表明，品系幼苗和成株期反应的表型变异的 61-91%和 59-77%分别由基因型组成解释。对于幼苗抗性，混合线性模型（MLM）鉴定了 8 个新的和 9 个以前报道的数量性状位点（QTL），而固定和随机模型循环概率统一（FarmCPU）检测到 12 个新的和 8 个以前报道的 QTL。对于田间抗性，MLM 鉴定了 12 个新的和 7 个以前报道的位点，而 FarmCPU 鉴定了 7 个新的和 9 个以前报道的位点。鉴定到了 Sr7a、Sr8155B1、Sr11、Sr13 等位基因、Sr17、Sr22/Sr25 和 Sr49 等区域。在染色体 3B、4A、6A、6B、7A 和 7B 上的新位点可能作为对抗硬粒小麦毒性菌株的抗性来源。染色体 6A 上的两个大效应标记可能可用于区分 Sr13（R1 和 R3）的抗性单倍型。需要进行 Sr13 的等位性测试，打破与 Sr22/Sr25 相关的有害效应，保留 Sr49 位点的抗性等位基因，以保护未来的品种免受新出现的菌株的侵害。
