Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Plant Dis. 2021 Jan;105(1):43-52. doi: 10.1094/PDIS-03-20-0471-RE. Epub 2020 Oct 27.
Clubroot, caused by Woronin, is an important disease of canola ( L.) that is managed mainly by planting clubroot-resistant (CR) cultivars. Field isolates of can be heterogeneous mixtures of various pathotypes, making assessments of the genetics of host-pathogen interactions challenging. Thirty-four single-spore isolates were obtained from nine field isolates of the pathogen collected from CR canola cultivars. The virulence patterns of the single-spore and field isolates were assessed on the 13 host genotypes of the Canadian Clubroot Differential (CCD) set, which includes the differentials of Williams and Somé et al. Indices of disease (IDs) severity of 25, 33, and 50% (±95% confidence interval) were compared as potential thresholds to distinguish between resistant and susceptible reactions, with an ID of 50% giving the most consistent responses for pathotype classification purposes. With this threshold, 13 pathotypes could be distinguished based on the CCD system, 7 on the differentials of Williams, and 3 on the hosts of Somé et al. The highest correlations were observed among virulence matrices generated using the three threshold IDs on the CCD set. Genetically homogeneous single-spore isolates gave a clearer profile of the pathotype structure. Novel pathotypes, not reported in Canada previously, were identified among the isolates. This large collection of single-spore isolates can serve as a reference in screening and breeding for clubroot resistance.
根肿病由黄单胞杆菌引起，是油菜（L.）的一种重要病害，主要通过种植抗根肿病（CR）品种来防治。田间分离的可以是各种致病型的异质混合物，这使得评估宿主-病原体相互作用的遗传基础具有挑战性。从 9 个抗根肿病油菜品种中收集的 9 个病原菌田间分离物中获得了 34 个单孢分离物。在加拿大根肿病鉴别寄主（CCD）组的 13 个寄主基因型上评估了单孢和田间分离物的毒力模式，该组包括威廉姆斯和 Somé 等人的鉴别寄主。25、33 和 50%（±95%置信区间）的疾病严重指数（IDs）作为区分抗性和敏感性反应的潜在阈值进行了比较，50%的 IDs 最有利于对致病型进行分类。根据 CCD 系统，可将 13 种致病型与该系统的鉴别寄主区分开来，7 种与威廉姆斯的鉴别寄主区分开来，3 种与 Somé 等人的鉴别寄主区分开来。在使用 CCD 组上的三个阈值 ID 生成的毒力矩阵之间观察到最高的相关性。遗传上同质的单孢分离物提供了更清晰的致病型结构图谱。在分离物中鉴定出了以前在加拿大未报道过的新致病型。该单孢分离物的大型集合可作为筛选和培育根肿病抗性的参考。
