Abstract

Powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is a major disease of wheat (Triticum aestivum) in Ontario, which can cause 20% yield loss. The development of resistant commercial wheat cultivars is the most economical means of controlling this disease, but only if the resistance genes used are incompatible with the virulence phenotypes present in the pathogen population. The virulence structure of Bgt in Ontario was examined in 2018 and 2019. Of the 42 single colony isolates collected in Ontario greenhouses and commercial fields, 40 virulence phenotypes, assigned VP1 to VP40, were identified on a set of 24 single-gene differential genotypes. Of the 24 resistance genes possessed by the differential genotypes, eight genes including Pm1a, Pm1b, Pm1c, Pm12, Pm16, Pm21, Pm37, and MlAG12 were effective against all of the Bgt isolates. Four genes including Pm3d, Pm29, Pm34, and NCAG13 were mostly effective with resistance reactions to more than 80% of the isolates. There were no significant differences in numbers of virulence genes per isolate between the two years, or between the greenhouse and field origins. The virulence frequencies of Bgt isolates for these effective and mostly effective genes were also not significantly affected by the year of collection and their origins, suggesting that the Bgt population is relatively stable. The effective genes identified in this study may be deployed singly or used for gene pyramiding in wheat breeding programs for developing powdery mildew-resistant cultivars in Ontario.

摘要

Blumeria graminis f.引起的白粉病。sp. 小麦( Bgt ) 是安大略省小麦 ( Triticum aestivum )的主要病害，可导致 20% 的产量损失。开发抗性商业小麦品种是控制该病害的最经济手段，但前提是所用抗性基因与病原体种群中存在的毒力表型不相容。Bgt的毒力结构2018 年和 2019 年对安大略省的 2018 年和 2019 年进行了检查。 在安大略省温室和商业田间收集的 42 个单菌落分离株中，在一组 24 个单基因差异基因型上鉴定了 40 个毒力表型，将 VP1 分配到 VP40。在差异基因型所具有的 24 个抗性基因中，包括Pm1a、Pm1b、Pm1c、Pm12、Pm16、Pm21、Pm37和MlAG12在内的 8 个基因对所有Bgt分离株均有效。四个基因，包括Pm3d、Pm29、Pm34和NCAG13对超过 80% 的分离株产生耐药反应，大部分是有效的。两年间或温室和大田来源之间，每个分离株的毒力基因数量没有显着差异。Bgt分离株对这些有效基因和大部分有效基因的毒力频率也不受收集年份及其来源的显着影响，表明Bgt种群相对稳定。本研究中鉴定的有效基因可单独部署或用于在安大略省开发抗白粉病品种的小麦育种计划中进行基因聚合。