XVI International Botanical Congess
Nucleotides of 967 bp and 1375 bp predicted to encode reverse transcriptase, RNase H and integrase of retroposons were amplified by PCR using genomic DNA of Tricholoma matsutake as a template. The former sequence is conserved in strains of T. matsutake and Tricholoma magnivelare whereas the latter is only in T. matsutake. No homolog of these fragments was detected in strains of 9 other species of Tricholoma and 3 other related genera. PCR using the internal repeated sequences as primers showed variations among strains of T. matsutake. The copy number of 967 bp fragment appears to be 60-fold higher than that of 1375 bp in the genome. Mycorrhizae formed between T. matsutake and Pinus densiflora were identified by PCR amplifying these fragments. Data suggest that retroposon-like elements are differentiated through the evolution of ectomycorrhizal basidiomycetes and offer us molecular means to index these organisms.