Larsen J E, Hollingsworth C R, Flor J, Dornbusch M R, Simpson N L, Samac D A
Department of Plant Pathology, University of Minnesota, St. Paul 55108.
Northwest Research and Outreach Center and Department of Plant Pathology, University of Minnesota, Crookston 56716.
Plant Dis. 2007 May;91(5):551-558. doi: 10.1094/PDIS-91-5-0551.
Brown root rot of alfalfa (Medicago sativa), caused by Phoma sclerotioides, has been reported in several states in the northern United States and in western Canada. A survey was conducted to determine the distribution of the fungus in Minnesota and Wisconsin. Isolates of the pathogen were recovered from roots of alfalfa, winter wheat, and perennial ryegrass plants. The internal transcribed spacer (ITS) 1, 5.8S, and ITS2 of the rDNA of the isolates from alfalfa and wheat were identical and matched the sequences of a P. sclerotioides isolate from Wyoming. The fungus was found to be widespread in both states and was detected in roots of alfalfa plants from 17 counties in Minnesota and 14 counties in Wisconsin using polymerase chain reaction (PCR)-based assays. A real-time PCR assay was developed that increased sensitivity of detecting the pathogen from plant tissues and soil. The isolates from alfalfa caused disease on inoculated winter wheat plants. Although the fungus was previously found associated with roots of diseased cereal and turfgrass plants, this is the first demonstration of pathogenicity of P. sclerotioides on wheat.
由核盘菌引起的苜蓿褐根腐病已在美国北部的几个州和加拿大西部被报道。开展了一项调查以确定该真菌在明尼苏达州和威斯康星州的分布情况。从苜蓿、冬小麦和多年生黑麦草植株的根部分离到了病原菌。来自苜蓿和小麦的分离株的核糖体DNA的内转录间隔区（ITS）1、5.8S和ITS2是相同的，并且与来自怀俄明州的核盘菌分离株的序列相匹配。发现该真菌在这两个州广泛分布，并且使用基于聚合酶链反应（PCR）的检测方法在明尼苏达州17个县和威斯康星州14个县的苜蓿植株根部检测到了该真菌。开发了一种实时PCR检测方法，提高了从植物组织和土壤中检测病原菌的灵敏度。来自苜蓿的分离株对接种的冬小麦植株致病。尽管该真菌此前被发现与患病谷物和草坪草植株的根部有关，但这是核盘菌对小麦致病性的首次证明。
