New Records of Powdery Mildews from Taiwan: Erysiphe ipomoeae comb. nov., E. aff. betae on Buckwheat, and E. neolycopersici comb. nov. on Cardiospermum halicacabum

Abstract

Erysiphe is the largest genus of powdery mildews (PMs), a group of obligate plant patho-genic fungi. Exploration of biodiversity generally relies on regional surveys and our aim is to inves-tigate the PMs in Taiwan. Collections of the fungi on five plant species around agricultural environ-ments were subjected to morphological and molecular characterization, using both internal transcribed spacer (ITS) and β-tubulin gene (TUB2) regions for the phylogenetic analyses. Erysiphe ipo-moeae comb. nov., a species able to infect Ipomoea obscura and I. aquatica demonstrated by pathogenic-ity tests, has been neotypified. The two buckwheat species, Fagopyrum esculentum and F. tataricum, are found to be hosts of E. aff. betae. These results suggest that hosts in some plant families can be infected by more than one Erysiphe pathogen, e.g., Convolvulaceae by E. ipomoeae and E. convolvuli and Polygonaceae by E. polygoni and E. aff. betae, respectively. In addition, phylogenetic analyses of PMs on Cardiospermum halicacabum and tomato belonging to the E. aquilegiae complex are allocated under E. neolycopersici comb. nov. This extends the potential host range of E. aquilegiae complex to the plant family Sapindaceae. We conclude that awareness of the host associations of PMs can po-tentially benefit crop disease management.