Evolution of mushroom mitochondrial DNA:Suillus and related genera

Abstract

Mapping studies were performed with 18 cloned probes on mitochondrial DNA (mtDNA) from 15 species ofSuillus and four species from three related genera of fleshy pore mushrooms (Boletaceae). WithinSuillus, mtDNAs vary in size from 36 to 121 kb, differ in gene order by only one major rearrangement, and have diverged in nucleotide sequence within the large subunit ribosomal RNA gene region by up to 2.9%. Three additional gene orders exist in related genera. Two of the three can be transformed into the predominantSuillus order by either one or two rearrangements. The fourth requires two to three rearrangements to be converted to any of the others. The minimum estimates of nucleotide divergence within the large subunit ribosomal RNA gene region vary from 8.3% to 11% in comparisons betweenSuillus and these related species. Trees based on restriction-site and size differences within the mitochondrial ribosomal RNA genes were consistent with the hypothesized sequence of genome rearrangements and provide suggestive evidence for a major expansion of the mitochondrial genome withinSuillus. Structural and sequence changes in mtDNA provided information about phylogenetic relationships within the Boletaceae.