Identification and pathogenicity of six fungal species causing canker and dieback disease on golden rain tree in Beijing, China

New species and records of Botryosphaeriales (Dothideomycetes) associated with tree dieback in Beijing, China

Botryosphaeriales species are important pathogens that have worldwide distribution. In this study, 23 Botryosphaeriales strains were isolated from 13 host species during a dieback disease survey in Beijing, China. Based on morphological and phylogenetic analyses, six Botryosphaeriales species were identified, including two new species named Dothiorellahortiarborum sp. nov. and Phaeobotryonfraxini sp. nov., and four new host records: Aplosporellaginkgonis from Cotinuscoggygriavar.cinereus, A.javeedii from Acermiyabei, Acertruncatum, Forsythiasuspensa, Lagerstroemiaindica, Sambucuswilliamsii, Syringavulgaris, Ulmuspumila, Xanthocerassorbifolium, A.yanqingensis from Acertruncatum, and Do.acericola from Forsythiasuspensa, Ginkgobiloba, and Syringaoblata. This study enriches the species diversity associated with tree dieback in Beijing, China, and contributes to the further study of the taxonomy of this order.

DNA barcoding and scanning electron microscopy reveals Erysiphe ahmadii sp. nov. and a new record Erysiphe populicola (Erysiphaceae, Helotiales) on salicaceous hosts from Pakistan

A new species of powdery mildew fungus Erysiphe ahmadii and a new record, Erysiphe populicola, on Salicaceae are described from Pakistan. In addition to light microscopy, scanning electron microscopy is also done to clearly demonstrate the surface characters of chasmothecia. E. ahmadii sp. nov. is characterized by large conidia ((-26)29-35(-37) × (-16)17-21(-23) μm), long chasmothecial appendages (198-286 μm) and small conidiophores. The novelty is confirmed by analyzing the genetic variation of internal transcribed spacer region (ITS1-5.8S-ITS2) of the ribosomal DNA gene, a universal fungal marker. E. populicola is characterized for the first time using molecular phylogenetic markers. Detailed descriptions along with scanning electron microscopy (SEM) photographs are provided in this paper. RESEARCH HIGHLIGHTS: Powdery mildews are obligate biotrophic pathogens of plants. Erysiphe ahmadii, a new powdery mildew fungus on willow trees, is described. First reference sequence of Erysiphe populicola is also generated. Both taxa are discussed in detail using macro- and micro-morphological and DNA barcoding techniques.