Department of Plant Pathology, University of California, Davis, c/o U.S. Agricultural Research Station, 1636 E. Alisal Street, Salinas 93905, USA.
Phytopathology. 2012 Nov;102(11):1071-8. doi: 10.1094/PHYTO-04-12-0067-R.
ABSTRACT Since 1995, lettuce in coastal California, where more than half of the crop in North America is grown, has consistently suffered from severe outbreaks of Verticillium wilt. The disease is confined to this region, although the pathogen (Verticillium dahliae) and the host are present in other crop production regions in California. Migration of the pathogen with infested spinach seed was previously documented, but the geographic sources of the pathogen, as well as the impact of lettuce seed sparsely infested with V. dahliae produced outside coastal California on the pathogen population in coastal California remain unclear. Population analyses of V. dahliae were completed using 16 microsatellite markers on isolates from lettuce plants in coastal California, infested lettuce seed produced in the neighboring Santa Clara Valley of California, and spinach seed produced in four major spinach seed production regions: Chile, Denmark, the Netherlands, and the United States (Washington State). California produces 80% of spinach in the United States and all seed planted with the majority infested by V. dahliae comes from the above four sources. Three globally distributed genetic populations were identified, indicating sustained migration among these distinct geographic regions with multiple spinach crops produced each year and repeated every year in coastal California. The population structure of V. dahliae from coastal California lettuce plants was heavily influenced by migration from spinach seed imported from Denmark and Washington. Conversely, the sparsely infested lettuce seed had limited or no contribution to the Verticillium wilt epidemic in coastal California. The global trade in plant and seed material is likely contributing to sustained shifts in the population structure of V. dahliae, affecting the equilibrium of native populations, and likely affecting disease epidemiology.
摘要自 1995 年以来，加利福尼亚沿海地区的生菜（北美一半以上的生菜都产自这里）一直受到严重的黄萎病侵袭。这种疾病只限于该地区，尽管病菌（大丽轮枝菌）和宿主在加利福尼亚的其他作物种植区都存在。受污染的菠菜种子携带病菌的迁移此前已有记录，但病菌的地理来源，以及产自加利福尼亚沿海地区以外的、带有稀疏大丽轮枝菌的生菜种子对加利福尼亚沿海地区病菌种群的影响仍不清楚。利用 16 个微卫星标记对来自加利福尼亚沿海生菜植株、产自加利福尼亚圣克拉拉谷的受污染生菜种子以及产自智利、丹麦、荷兰和美国（华盛顿州）四个主要菠菜种子生产区的菠菜种子中的大丽轮枝菌进行了种群分析。加利福尼亚州生产了美国 80%的菠菜，并且种植的大部分种子都受到了大丽轮枝菌的感染，这些种子都来自上述四个来源。确定了三个在全球范围内分布的遗传种群，这表明在这些不同的地理区域之间存在持续的迁移，每年都会种植多批菠菜，而且在加利福尼亚沿海地区每年都会重复种植。来自加利福尼亚沿海生菜植株的大丽轮枝菌的种群结构受到了从丹麦和华盛顿进口的菠菜种子的迁移的严重影响。相反，带有稀疏感染的生菜种子对加利福尼亚沿海地区的黄萎病流行几乎没有或没有贡献。植物和种子材料的全球贸易可能导致大丽轮枝菌种群结构的持续变化，影响本地种群的平衡，并可能影响疾病的流行病学。
