Microfungi associated with plant diseases on horticultural vegetation in southwestern China

Horticultural plants are essential natural resources upon which human survival relies, offering diverse means of sustenance, including food, medicine, chemical raw materials, construction materials, landscaping, cultural significance, and tourism. In recent years, the widespread and increasingly harmful fungal diseases in horticultural plants have prompted this study to investigate the diversity and composition of their pathogenic fungi. Over the past six years (2019 to 2024), diseased tissues from horticultural plants in southwestern China were collected and assessed using measurements based on both morphological characteristics and phylogenetic analyses involving combined multi-locus sequence data. A total of 38 fungi were classified into two phyla, Ascomycota and Basidiomycota, and four classes: Sordariomycetes (Amphisphaeriales, Diaporthales, Glomerellales, Hypocreales, and Phyllachorales), Dothideomycetes (Botryosphaeriales, Capnodiales, Cladosporiales, Mycosphaerellales, Myriangiales, and Pleosporales), Exobasidiomycetes (Exobasidiales), and Leotiomycetes (Helotiales), totaling 13 orders. In this paper, we propose one new genus in Pleosporales (Paramassarina) and 13 new species, namely Colletotrichum cymbidiumdis, Conidiocarpus cinnamomeus, Cladosporium viciae, Cytospora sichuanense, Diaporthe erythrinae, Exosporium rhapidis, Fumagospora cinnamomi, Neocosmospora phalaenopsidis, Neoscytalidium hylocereum-undulatum, Paramassarina euonymicola, Paraphoma populi, Phaeosphaeria phormii, and Pseudocercospora populina. Additionally, we report 19 species as new host or geographical records, 17 of which represent new host records, including Botryosphaeria dothidea, Cladosporium guizhouense, Colletotrichum cymbidiicola, Col. guangyuanense, Col. plurivorum, Cytospora predappioensis, Diaporthe eres, Di. middletonii, Di. sojae, Drepanopeziza brunnea, Elsinoe araliae, Graphiola phoenicis, Lasiodiplodia pseudotheobromae, Neopestalotiopsis concentrica, Neop. dimorphospora, Neovaginatispora fuckelii, and Paraconiothyrium brasiliense, and two species are new host and geographical record, namely Pestalotiopsis oryzae and Phyllosticta citribrasiliensis. Morphological illustrations, phenotypic descriptions, and phylograms are provided to elucidate the placement of the new collections in this study. These fungi, originating from infected tissues, are linked to diseases either through observed symptoms or previous studies suggesting their potential pathogenicity. Further research is needed to confirm the pathogenicity of these species using Koch's postulates.