Department of Plant Pathology, University of California-Davis, Salinas, CA, USA.
Fungal Genet Biol. 2010 May;47(5):416-22. doi: 10.1016/j.fgb.2010.02.003. Epub 2010 Feb 8.
The fungal pathogen Verticillium dahliae has resulted in significant losses in numerous crops in coastal California, but lettuce remained unaffected until the mid-1990s. Since then outbreaks have decimated entire fields, but the causes of this sudden susceptibility of lettuce remain elusive. The population structure of V. dahliae isolated from coastal California (n=123) was investigated with 22 microsatellite markers, and compared with strains from tomato in central California (n=60), spinach seed imported from Washington State and Northern Europe (n=43), and ornamentals from Wisconsin (n=17). No significant differentiation was measured among hosts in coastal California or with the spinach and Wisconsin ornamental sampling groups. In contrast, the tomato sampling group was significantly differentiated. Significant gene flow was measured among the various geographic and host sampling groups, with the exception of tomato. Evidence of recombination in V. dahliae was identified through gametic disequilibrium and an exceedingly high genotypic diversity. The high incidence of V. dahliae in spinach seed and high planting density of the crop are sources of recurrent gene flow into coastal California, and may be associated with the recent outbreaks in lettuce.
真菌病原体维氏枝孢菌（Verticillium dahliae）导致加利福尼亚沿海地区许多作物遭受重大损失，但生菜直到 20 世纪 90 年代中期才受到影响。从那时起，疫情已经摧毁了整个田地，但生菜突然易感染的原因仍然难以捉摸。使用 22 个微卫星标记研究了从加利福尼亚沿海地区（n=123）分离的维氏枝孢菌的种群结构，并将其与来自加利福尼亚中部的番茄（n=60）、从华盛顿州和北欧进口的菠菜种子（n=43）以及来自威斯康星州的花卉（n=17）的菌株进行了比较。在沿海地区或菠菜和威斯康星花卉采样组的宿主之间未测量到明显的分化。相比之下，番茄采样组存在显著分化。在各个地理和宿主采样组之间测量到了显著的基因流，番茄除外。通过配子不平衡和极高的基因型多样性鉴定了维氏枝孢菌中的重组证据。菠菜种子中维氏枝孢菌的高发生率和作物的高密度种植是沿海加利福尼亚地区反复基因流的来源，可能与生菜最近的疫情有关。
