Studies On Morphological Features And Molecular Systematics Of Erysiphe And Podosphaera

In this paper, descriptions, illustrations and discussions of the anamorphic characters of Podosphaera and Erysiphe are provided based on the observation of specimens. The species of powdery mildews (Erysiphales) were treated according to the new taxonomic system. The rDNA sequences analyses were used to discuss the phylogenetic of two genera with the anamorphic states.In the present work, studies of morphological classification on Podosphaera and Erysiphe were carried on. As a result of the survey, the 25 species morphology of Erysiphe have been described, which belong to Erysiphe sect. Erysiphe 14 species, sect. Microsphaera 7 species and sect. Uncinula 2 species. There were three new record species to Northeast China, Erysiphe ulmariae, Erysiphe macleayae, Erysiphe huayinensis. Two new varieties record to Jilin province, Erysiphe vanbruntiana var. vanbruntiana and Erysiphe trifolii var. trifolii. Moreover there were 2 new record host plants in the world, Gueldenstaedtia maritima Maxim. and Sambucus manshurica Kitag.. Two new genus record host plants of Northeast China, Macleaya cordata (Willd.) R. Br., and Coriandrum sativum L. Two new record host plants to Northeast China, Glycine soja (L)Sieb.& Zucc., and Salix matsudana Koidz. The anamorphs of Erysiphe s.str., Microsphaera, and Uncinula are uniform and belong in Oidium subgen. Pseudoidium, appressoria were lobed, germ tubes were polygoni-type.As a result of the survey, the 9 species morphology of Podosphaera have been described, which belong to Podosphaera sect. Podosphaera 2 species, and sect. Sphaerotheca 7 species. There was one new record species in China, Podosphaera euphorbiae-helioscopiae. One new record species to Northeast China, Podosphaera spiraeae. Moreover there were 2 new record host plants in the world, Euphorbia pekinensis Rupr. and Filipendula intermedia (Glehn) Juzep., one new genus record host plants to Northeast China, Catalpa ovata G. Don.. The anamorphs of Podosphaera and Sphaerotheca were Oidium subgen. Fibroidium, appressoria was indistinct, germ tubes arising from the middle portion of the conidia, short, forked and broadened, conidia with fibrosin bodies.A phylogenetic analysis of 34 species of Erysiphe and Podosphaera was done using sequences of the rDNA ITS regions and the D1/D2 domains of the 28S rDNA. By combining the ITS and 28S rDNA sequences of other species available in the Genbank phylogeny trees were built. The results revealed Erysiphe s.str., Microsphaera, and Uncinula did not group into separate monophyletic lineages, but the species of these genera formed several small, mixed clusters, which cannot be phylogenetically distinguished from each other. It was supported Microsphaera and Uncinula should be integrated into Erysiphe s.str.. Podosphaera and Sphaerotheca were closely related, there two genera cannot be distinguished using the molecular data and do not form distinct clades. It was concluded that all Sphaerotheca species could be changed to Podosphaera. The applicability of ITS to systematic studies of species and closely related genera was highly appreciated with some limitations. And compared to rDNA ITS regions, the D1/D2 domains of the 28S rDNA were applied to identification between genera. The data suggests that ITS may be a good candidate for DNA barcoding of powdery mildew, but further studies are necessary to confirm the accurateness of the ITS gene. This work was first applied to assess rDNA sequences analysis among Podosphaera and Erysiphe, and fill the gaps of the two genera studies of anamorph in China.