Molecular phylogeny reveals phenotypic evolution of powdery mildews (Erysiphales, Ascomycota)

Powdery mildew fungi, comprising 16 genera and ca. 900 species, are exclusively obligate biotrophs of plants. Although several publications have addressed the phylogeny and evolution of powdery mildews based on morphology and host relationships, this review focuses on the evolution of several phenotypic characters based on molecular phylogeny: (1) morphology of appendages; (2) mycelium, ectoparasitic or endoparasitic; (3) number of asci per chasmothecium (fruiting body of powdery mildews), e.g., one to several; (4) conidiogenesis, conidia catenescent (i.e., maturing in chains: Euoidium-type) or maturing one at a time (Pseudoidium-type). Putative ancestral features of the powdery mildews are described as follows. In teleomorphs, large-sized chasmothecia, containing many 8-spored asci, had many appendages with uncinate-circinate apices, arising around the supraequatorial part of chasmothecia. In anamorphs, conidia were produced in chains (Euoidium-type) without distinct fibrosin bodies. Parasitism was ectoparasitic.