MITOCHONDRIAL-DNA POLYMORPHISMS IN LACCARIA-BICOLOR, L-LACCATA, L-PROXIMA AND L-AMETHYSTINA

The mitochondrial DNA (mtDNA) from 25 Laccaria bicolor, 8 L. laccata, 3 L. proxima and 2 L. amethystina isolates was examinated by restriction fragment length polymorphism (RFLP) analysis. Whole-cell DNA from Laccaria isolates was digested with Bam HI, Bgl II and Hind III and probed in Southern hybridizations with cloned mitochondrial fragments from L. bicolor. Analysis of restriction fragment length polymorphisms indicated that mtDNA fragment patterns can be used as additional taxonomic characters for delimiting Laccaria spp. However, intraspecific variation was very high with almost no similarity observed among the four biological species of L. laccata or between the 2 isolates of L. amethystina. A high level of variability was also detected within L. bicolor and several subgroups, possibly biological species, were discernible among the L. bicolor isolates examined. No major discrepancies were observed between the trends indicated by RFLP results on mtDNA and those on nuclear ribosomal DNA. As most of the Laccaria isolates had unique overall mitochondrial pattern, this variability could be used for isolate typing.