Holomorph morphology and molecular phylogeny confirm Erysiphe necator var. necator causing powdery mildew on Vitis flexuosa in Korea

Powdery mildew on Vitis flexuosa has been reported as Erysiphe necator based on its anamorphic stage in Japan and Korea. Although V. flexuosa has a wide native range across Asian tropical and temperate climates, E. necator on this wild plant remains understudied. Specimens collected from various locations in Korea were morphologically examined and molecularly analyzed. This study provides a description and illustration of the holomorph (anamorph + teleomorph) of E. necator var. necator on V. flexuosa, supported by molecular phylogeny based on sequencing of the internal transcribed spacer (ITS) region and large subunit (LSU) gene of the rDNA from three representative Korean specimens. This study represents the first finding of the teleomorphic stage of E. necator var. necator in Korea, the first recognition of bristle-like appendages on the chasmothecia, and the first ITS and LSU sequence data for E. necator var. necator on V. flexuosa globally. These findings contribute to the understanding of the Vitis-Erysiphe association.