Molecular phylogeny and evolution of subsection Magnicellulatae (Erysiphaceae: Podosphaera) with special reference to host plants

The subsection Magnicellulatae of the genus Podosphaera section Sphaerotheca belongs to the tribe Cystotheceae of the Erysiphaceae, which has the characteristic of producing catenate conidia with distinct fibrosin bodies. In this study, we newly determined the nucleotide sequences of the D1/D2 domains of the 28 S rDNA region and the sequences of the rDNA internal transcribed spacer (ITS) region to investigate the relationships between the phylogeny of this fungal group and their host plants. The results indicated that the 28 S rDNA region is too conservative for phylogenetic analysis of this fungal group. The phylogenetic analysis using 95 ITS sequences demonstrated that two or more Magnicellulatae taxa often infect the same plant genus or species. Although there is a close relationship between Magnicellulatae and asteraceous hosts, this association seems to be not as strict as that between Golovinomyces and the Asteraceae. The difference between the two fungal groups may be explained by their different evolutionary timing.