1998 Volume 64 Issue 5 Pages 451-457
Electrophoretic analysis of total DNA extracted from Rhizoctonia solani Kühn AG-2-2 IV isolate PE-42, the causal fungus of large patch of zoysiagrass, revealed a 3.0-kb band in addition to the band of chromosomal DNA. Because the band was regarded as a double-stranded plasmid DNA based on restriction enzyme analyses, it was designated as a PE-42 plasmid fragment. The PE-42 plasmid DNA recovered from agarose gel hybridized to DNA of all 22 large patch isolates used, but not to DNA of other zoysiagrass pathogens. Southern hybridization analysis using the PE-42 plasmid DNA as a probe showed that the DNA could be used as a marker to distingush the large patch fungus from other intraspecific groups of Rhizoctonia solani. DNAs extracted from zoysiagrasses having various stages of large patch symptom and yellow patch symptom or having no symptoms (healthy) were subjected to Southern hybridization. The PE-42 plasmid DNA hybridized to the DNAs from zoysiagrass with large patch symptom, but not to DNAs from yellow patch and heathy plants. Thus, the PE-42 plasmid DNA was considered to be useful as a probe for molecular diagnosis of large patch of zoysiagrass.