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Poster: Biology & Disease Mgmt: Virology


Discovery of various dsRNA mycoviruses in Trichoderma spp. causing green mold disease of shiitake Lentinula edides
D. KIM (1) (1) Chonbuk National University, South Korea

A total of 315 fungal isolates causing green mold disease were collected from contaminated artificial logs and sawdust bags used for cultivating shiitake mushroom Lentinula edodes in Korea and were analyzed for the presence of dsRNA. dsRNA, which was purified using dsRNA-specific chromatography and verified by dsRNA-specific RNaseIII digestion, was detected in 32 isolates. The molecular taxonomy of dsRNA-infected isolates based on the ITS region of the rDNA indicated that all isolates belonged to the Trichoderma spp. The number and size of dsRNAs varied among isolates and the band patterns could be categorized into 15 groups. The most common dsRNA group, groupVI, occurred in 10 isolates encompassing three species of Trichoderma. Partial cDNA clones were obtained from two selected dsRNA groups and the sequence comparison of the cloned fragments of these dsRNAs revealed a high degree of similarity to sequences of a hypothetical protein and polyprotein genes of other mycoviruses, indicating the existence of mycoviruses in Trichoderma spp. Northern blot analysis using cloned cDNA showed specific hybridizing patterns in the dsRNA bands for isolates from which the clones were obtained, suggesting that many different mycoviruses, which have not been identified yet, exist in Trichoderma spp..