Kull L S, Pedersen W L, Palmquist D, Hartman G L
Department of Crop Sciences, University of Illinois, Urbana 61801.
United States Department of Agriculture-Agricultural Research Service (USDA-ARS), MWA Biometrician, Peoria, IL.
Plant Dis. 2004 Apr;88(4):325-332. doi: 10.1094/PDIS.2004.88.4.325.
Population variability of Sclerotinia sclerotiorum, the causal organism of Sclerotinia stem rot of soybean, was determined by mycelial compatibility grouping (MCG) and isolate aggressiveness comparisons. MCG and aggressiveness of S. sclerotiorum isolates from diverse hosts and geographic locations (Diverse Set, 24 isolates), from a soybean field in Argentina (Argentine Set, 21 isolates), and from soybean fields in DeKalb and Watseka, Illinois (DeKalb Set, 124 isolates, and Watseka Set, 130 isolates) were assessed. Among 299 isolates tested, 42 MCGs were identified, and 61% were represented by single isolates observed at single locations. Within the Diverse Set, 17 MCGs were identified; 1 MCG consisted of six isolates, and 16 MCGs consisted of one isolate each. Nine MCGs were identified within the Argentine field with two MCGs composed of either five or six isolates, two MCGs composed of two isolates, and the remaining composed of one isolate each. Each Illinois field was a mosaic of MCGs, but MCG frequencies differed between the two fields. Common MCGs were identified among the Diverse, DeKalb, and Watseka Sets, but no MCGs within the Argentine Set were observed with other sets. MCG 8 was the most frequently sampled and widely dispersed MCG and occurred at a frequency of 29, 36, and 62% in the Diverse, DeKalb, and Watseka Sets, respectively. Variation in isolate aggressiveness was assessed using a limited-term, plug inoculation technique. Isolate aggressiveness varied (P = 0.001) within the Diverse, Argentine, DeKalb, and Watseka Sets. Within widely dispersed MCGs, isolate aggressiveness varied (P ≤ 0.10); however, within locally observed MCGs detected only in single fields, isolate aggressiveness did not vary. Additionally, individual MCGs within the DeKalb and Watseka Sets differed in isolate aggressiveness. Using six soybean cultivars and six S. sclerotiorum isolates, no cultivar-isolate interaction was detected, but resistant and susceptible cultivars performed similarly when inoculated with either less or highly aggressive isolates. Pathogen population structure and variability in isolate aggressiveness may be important considerations in disease management systems.
通过菌丝体亲和性分组（MCG）和分离株致病性比较，确定了大豆菌核病的病原菌核盘菌的群体变异性。评估了来自不同寄主和地理位置的核盘菌分离株（多样组，24个分离株）、来自阿根廷一个大豆田的分离株（阿根廷组，21个分离株）以及来自伊利诺伊州迪卡尔布和瓦西卡大豆田的分离株（迪卡尔布组，124个分离株和瓦西卡组，130个分离株）的MCG和致病性。在测试的299个分离株中，鉴定出42个MCG，61%由在单个地点观察到的单个分离株代表。在多样组中，鉴定出17个MCG；1个MCG由6个分离株组成，16个MCG各自由1个分离株组成。在阿根廷田间鉴定出9个MCG，其中2个MCG由5个或6个分离株组成，2个MCG由2个分离株组成，其余各自由1个分离株组成。伊利诺伊州的每个田间都是MCG的镶嵌体，但两个田间的MCG频率不同。在多样组、迪卡尔布组和瓦西卡组中鉴定出了常见的MCG，但在阿根廷组中未观察到与其他组相同的MCG。MCG 8是采样频率最高且分布最广的MCG，在多样组、迪卡尔布组和瓦西卡组中的出现频率分别为29%、36%和62%。使用有限期的菌塞接种技术评估分离株致病性的变异。在多样组、阿根廷组、迪卡尔布组和瓦西卡组中，分离株致病性存在差异（P = 0.001）。在广泛分布的MCG中，分离株致病性存在差异（P≤0.10）；然而，在仅在单个田间检测到的局部观察到的MCG中，分离株致病性没有差异。此外，迪卡尔布组和瓦西卡组中的单个MCG在分离株致病性方面也存在差异。使用6个大豆品种和6个核盘菌分离株，未检测到品种 - 分离株相互作用，但接种致病性较低或较高的分离株时，抗性和感病品种的表现相似。病原菌群体结构和分离株致病性的变异性可能是病害管理系统中的重要考虑因素。
