Exploring multifaceted roles of bambusicolous Apiospora in Phyllostachys sp.

Bamboo plays a crucial role in mitigating climate change. Among various microorganisms inhabiting bamboo, Apiospora is a common bambusicolous fungus that induces black spots, functioning either as a saprobe or a plant pathogen. However, the diversity and ecological roles of Apiospora as an endophyte in bamboo remain poorly understood. This study explored the diversity and ecological functions of bambusicolous Apiospora in Phyllostachys forests. Bamboo samples representing different stages—young (one-year-old, without black spots), mature (aged three years, few black spots), and dead (with many black spots)—were collected. Microbiome analyses across different tissues (culm, leaf, root) and environmental samples (forest soil) revealed diverse Apiospora species throughout the bamboo lifecycle. Notably, Ap. hysterina emerged as a prevalent endophyte, inhabiting not only mature but also younger, healthier bamboo stages. Biological activity assays, including antioxidant, antifungal, and plant hormone tests, indicated that Ap. hysterina exhibits mutualistic interactions beneficial to bamboo. Conversely, genomic analyses of carbohydrate-active enzyme profiles and biosynthetic gene clusters suggested a pathogenic potential driven by secondary metabolites. These findings reveal the widespread presence of Apiospora species as endophytes from the early to senescent bamboo stages, highlighting Ap. hysterina ’s dual capacity as a pathogen and symbiont. Our study underscores the complexity of bambusicolous Apiospora ’s ecological roles, emphasizing the need for further investigation into its interactions with bamboo ecosystems.