Pathogen Survey in Agrocybe chaxingu and Characterization of the Dominant Pathogen Fuligo gyrosa

Agrocybe chaxingu is a commercially important edible mushroom in China, valued for its rich bioactive compounds and distinctive umami flavor. In recent years, frequent disease outbreaks have severely limited production, as many pathogens spread rapidly and are difficult to control, posing a significant threat to the sustainable development of the industry. In this study, a systematic disease survey across major A. chaxingu cultivation areas in Jiangxi Province led to the isolation and identification of 17 potential fungal pathogens and 2 potential myxomycete pathogens using combined morphological characterization and multilocus phylogenetic analyses including the internal transcribed spacer (ITS) region, 28S large subunit ribosomal RNA (LSU), translation elongation factor (tef1), RNA polymerase largest subunit (rpb1), RNA polymerase second largest subunit (rpb2), Histone (H3), Beta tubulin (tub2), and 18S ribosomal RNA (18S rRNA). Among the identified diseases, white slime disease showed the highest incidence (17.3%) and was attributed to the slime mold Fuligo gyrosa, with pathogenicity confirmed according to Koch’s postulates. F. gyrosa proved highly virulent to both fruiting bodies and mycelia, enveloping host mycelium via plasmodial expansion, inhibiting growth, inducing structural rupture, and causing progressive degradation. Infection was accompanied by the deposition of characteristic stress-related pigments in the mycelium. This study provides the first detailed characterization of F. gyrosa infection dynamics in A. chaxingu mycelium. These findings provide new insights into the myxomycete pathogenesis in edible fungi and provide a foundation for the accurate diagnosis, targeted prevention, and sustainable management of diseases in A. chaxingu cultivation.