Phylogeny and a new species of Sparassis (Polyporales, Basidiomycota): evidence from mitochondrial atp6, nuclear rDNA and rpb2 genes

Abstract

Three nuclear genes, lsu-rDNA (encoding nuclear large subunit rDNA), ITS (encoding the rDNA internal transcribed spacers and 5.8 S rDNA) and rpb2 (encoding the second largest subunit of RNA polymerase II), and the mitochondrial gene atp6 (encoding the sixth subunit of ATP synthase), were sequenced from all recognized Sparassis lineages. Sparassis latifolia sp. nov. from boreal coniferous forests in China is described based on morphological, ecological, geographical and molecular data. The nuclear gene phylogeny strongly supported groups corresponding to morphological differences, geographic distribution and host shifts among species that produce clamp connections, such as S. crispa from Europe, S. radicata from western North America and S. latifolia from Asia. The atp6 phylogeny however showed no divergence among these three species. For clampless Sparassis species, such as S. spathulata from eastern North America, S. brevipes and a new species from Europe, the atp6 phylogeny was congruent with the nuclear gene phylogeny. Sparassis cystidiosa is basal in the nuclear tree but sister to S. brevipes-S. spathulata clade in the ATP6 tree. The differences between the phylogenetic inferences from the atp6 gene and those from nuclear genes within Sparassis species are discussed.