Puri Krishna D, Gurung Suraj, Short Dylan P G, Atallah Z K, Sandoya German, Davis R Michael, Hayes Ryan J, Subbarao Krishna V
First, third, sixth, and eighth authors: Department of Plant Pathology, University of California, Davis; second author: Sakata Seed America, Salinas, CA; fourth author: Hartnell College, Salinas, CA 93905; fifth author: Department of Horticultural Science, Everglades Research and Education Center, University of Florida, Belle Glade; and seventh author: United States Department of Agriculture-Agricultural Research Service, Salinas, CA.
Phytopathology. 2017 Nov;107(11):1417-1425. doi: 10.1094/PHYTO-02-17-0071-R. Epub 2017 Aug 30.
Understanding pathogen evolution over time is vital for plant breeding and deployment of host resistance. In the context of a soilborne pathogen, the potential of host-directed evolution of a Verticillium dahliae race 1 isolate and genotypic variation of V. dahliae associated with two major hosts (lettuce and tomato) were determined. In total, 427 isolates were recovered over 6 years from a resistance screening nursery infested with a single V. dahliae race 1 isolate. In a separate study, an additional 206 isolates representing 163 and 43 isolates from commercial lettuce and tomato fields, respectively, were collected. Analyses of isolates recovered from the screening nursery over 6 years revealed no changes in the race and mating type composition but did uncover seven simple sequence repeat (SSR) variant genotypes. No significant genotypic variation in V. dahliae was observed between or within fields of either lettuce or tomato but pathogen populations were significantly differentiated between these two hosts. Replicated virulence assays of variant SSR genotypes on lettuce differential cultivars suggested no significant difference in virulence from the wild-type race 1 isolate introduced into the field. This suggests that deployed race 1 host resistance will be robust against the widespread race 1 populations in lettuce-growing regions at least for 6 years unless novel pathogen genotypes or races are introduced into the system.
了解病原体随时间的进化对于植物育种和宿主抗性的应用至关重要。在土传病原体的背景下，测定了大丽轮枝菌1号生理小种分离株的宿主定向进化潜力以及与两种主要宿主（生菜和番茄）相关的大丽轮枝菌的基因型变异。在6年的时间里，从一个被单一的大丽轮枝菌1号生理小种分离株侵染的抗性筛选苗圃中总共回收了427个分离株。在另一项研究中，分别从商业生菜田和番茄田中收集了另外206个分离株，其中163个来自生菜田，43个来自番茄田。对6年中从筛选苗圃中回收的分离株的分析表明，生理小种和交配型组成没有变化，但确实发现了7种简单序列重复（SSR）变异基因型。在生菜或番茄的田间之间或田间内部，未观察到大丽轮枝菌有显著的基因型变异，但这两种宿主之间的病原体群体存在显著差异。对生菜鉴别品种上的变异SSR基因型进行的重复毒力测定表明，其毒力与引入田间的野生型1号生理小种分离株没有显著差异。这表明，至少在6年内，已应用的1号生理小种宿主抗性将对生菜种植区广泛存在的1号生理小种群体具有抗性，除非新的病原体基因型或生理小种被引入该系统。
