Disease-induced changes in Panax ginseng phyllosphere fungal community assembly and functional adaptation

Phyllosphere microorganisms play essential roles in plant health and disease resistance, yet their responses to pathogen infections remain poorly understood. Panax ginseng is susceptible to multiple fungal diseases, which threaten its quality and yield. This study aimed to clarify the underlying disease resistance mechanisms of Panax ginseng by analyzing the phyllosphere fungal communities associated with fungal infections.

Phyllosphere fungal communities of healthy Panax ginseng plants and those with three fungal infections (gray mold, damping-off and root rot) were compared to explore the disease resistance mechanisms related to fungal community changes.

Results revealed distinct niche differentiation: leaves were dominated by Basidiomycota (82.0%), while stems harbored more Ascomycota (94.2%), including pathogens like Monilinia laxa (35.73%). Fungal infection significantly reduced microbial alpha diversity, altered community structure (PERMANOVA, p = 0.001), and destabilized co-occurrence networks (modularity decreased from 0.8501 to 0.8116). Functional prediction indicated downregulation of key metabolic pathways (e.g., NAD/NADP interconversion, phospholipid biosynthesis). Disease stress induced an enrichment of potentially beneficial taxa (e.g., Rhodotorula) in leaves, indicative of a limited antagonistic response, while the overall community was ultimately dominated and disrupted by pathogens.

Elucidating these compositional shifts of phyllosphere fungal communities advances the understanding of plant-microbe-pathogen interactions and provides a critical theoretical groundwork for development of microbiome-driven early disease diagnosis, resistance breeding, and eco-friendly disease control strategies for Panax ginseng.