Lamour K H, Hausbeck M K
Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville 37996-4560.
Department of Plant Pathology, Michigan State University, East Lansing 48824-1312.
Plant Dis. 2003 Jul;87(7):841-845. doi: 10.1094/PDIS.2003.87.7.841.
Phytophthora capsici is a limiting factor for some vegetable producers in Michigan despite crop rotation and fungicide applications. Our objective was to assess the effect of crop rotation on the survival of P. capsici at a naturally infested site in Michigan planted to cucumbers in 1998, corn in 1999 and 2000, and tomatoes in 2001. Isolates were characterized for compatibility type (CT), mefenoxam sensitivity, and amplified fragment length polymorphism (AFLP) marker profiles, and compared with isolates recovered from other locations in Michigan during the same time period. The A1:A2 CT ratio was 1:1, and approximately 60% of the isolates recovered in both years were intermediately sensitive or insensitive to mefenoxam. The majority of the isolates (89%) had unique AFLP fingerprints, and no members of the same clonal lineage were recovered among years. Isolates from this location were more similar to each other than to isolates from other locations in Michigan, and it was not possible to distinguish isolates based on the year of isolation. Genetic similarity analyses indicate that isolates from this location are part of a genetically distinct outcrossing population. These data indicate that P. capsici persisted as oospores for the 2 years between cucumbers and tomatoes, and that crop rotation and mefenoxam are not likely to provide economic control.
尽管采用了轮作和施用杀真菌剂措施，但辣椒疫霉仍是密歇根州一些蔬菜种植者面临的限制因素。我们的目标是评估轮作对辣椒疫霉在密歇根州一个自然感染地块上存活情况的影响，该地块1998年种植黄瓜，1999年和2000年种植玉米，2001年种植番茄。对分离株进行了交配型（CT）、甲霜灵敏感性和扩增片段长度多态性（AFLP）标记谱特征分析，并与同一时期从密歇根州其他地点分离得到的菌株进行比较。A1:A2交配型比例为1:1，两年中分离得到的菌株约60%对甲霜灵呈中度敏感或不敏感。大多数分离株（89%）具有独特的AFLP指纹图谱，不同年份未分离到同一克隆谱系的成员。该地点的分离株彼此之间比与密歇根州其他地点的分离株更为相似，且无法根据分离年份区分分离株。遗传相似性分析表明，该地点的分离株是一个基因独特的异交群体的一部分。这些数据表明，辣椒疫霉在黄瓜和番茄种植的两年间以卵孢子形式存活，轮作和甲霜灵不太可能实现经济有效的防治。
