Abstract

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), has potential to cause major yield losses in durum wheat. Development of durum cultivars with improved resistance to stem rust is a sustainable option for effective control of this disease. This study was conducted to identify genomic regions associated with resistance to Ug99-derived Pgt races using a doubled haploid (DH) mapping population produced from a cross between the resistant experimental line A9919-BY5C and the moderately susceptible cultivar ‘Strongfield’. The parents and DH lines were phenotyped for adult plant disease severity and infection response at Njoro, Kenya, for four years, and for seedling reaction to race TTKSK in a containment facility near Morden, Canada. Composite interval mapping using 612 SNP and DArT markers indicated four significant QTL for resistance to stem rust on chromosomes 1B, 4A, 5B, and 6A. A major and stable QTL from A9919-BY5C was identified on the short arm of chromosome 6A (6AS), which accounted for 71% of variation explained for seedling resistance and up to 46% for field resistance. This QTL mapped near the Sr8 locus and may be Sr8155B1, or a novel gene at the same location. Another QTL for adult plant resistance from A9919-BY5C was mapped on chromosome 1B that explained up to 14% of the phenotypic variation and likely is Sr14. Two minor QTL were identified in ‘Strongfield’ on chromosomes 4A and 5B that were inconsistent over years. Markers associated with the 6AS and 1B QTL can be used to proactively stack resistance to Ug99-derived races of Pgt into Canadian durum wheat.

摘要

茎锈病，由禾本科 Puccinia graminis f.引起。sp. 小麦( Pgt ) 有可能导致硬粒小麦的主要产量损失。开发具有更高抗茎锈病能力的硬粒小麦品种是有效控制该病害的可持续选择。本研究旨在鉴定与 Ug99 衍生Pgt抗性相关的基因组区域使用由抗性实验品系 A9919-BY5C 和中度敏感品种“Strongfield”杂交产生的双单倍体 (DH) 作图种群对种族进行了分析。亲本和 DH 品系在肯尼亚 Njoro 进行了四年的成年植物疾病严重程度和感染反应的表型分析，并在加拿大 Morden 附近的一个收容设施中对 TTKSK 种的幼苗反应进行了表型分析。使用 612 个 SNP 和 DArT 标记的复合区间作图表明，染色体 1B、4A、5B 和 6A 上有四个显着的 QTL 对茎锈病的抗性。在 6A 号染色体 (6AS) 的短臂上鉴定出一个来自 A9919-BY5C 的主要且稳定的 QTL，占幼苗抗性变异的 71% 和田间抗性变异的 46%。该 QTL 位于Sr8基因座附近，可能是Sr8155B1，或同一位置的新基因。来自 A9919-BY5C 的另一个成年植物抗性 QTL 定位在染色体 1B 上，解释了高达 14% 的表型变异，可能是Sr14。在 'Strongfield' 染色体 4A 和 5B 上发现了两个次要 QTL，这些 QTL 多年来不一致。与6AS和1B QTL相关的标记物可用于主动堆电阻到的Ug99真菌衍生的种族PGT成加拿大硬粒小麦。