Background Plants maintain the steady-state balance of the mutually beneficial symbiosis relationship with their endophytic fungi through secondary metabolites. Meanwhile endophytic fungi can serve as biological inducers to promote the biosynthesis and accumulation of valuable secondary metabolites in host plants through a variety of ways. The composition and structure of endophytic fungal community are affected by many factors, including tissues, seasons and so on. In this work, we studied the community diversity, temporal and spatial pattern of endophytic fungi detected from the roots, stems and leaves of Huperzia serrata in different seasons. The correlation between endophytic fungi and huperzine A (HupA) content in plants was analyzed. Results A total of 7005 operational taxonomic units were detected, and all strains were identified as 14 phyla, 54 classes, 140 orders, 351 families and 742 genera. Alpha diversity analysis showed that the diversity of endophytic fungi in stem and leaf was higher than that in root, and the diversity in summer (August) was lower than that in other months. NMDS analysis showed that the endophytic fungal communities of leaves, stems and roots were significantly different, and the root and leaf communities were also different between four seasons. Through correlation analysis, it was found that 33 genera of the endophytic fungi of H. serrata showed a significant positive correlation with the content of HupA (p < 0.05), of which 13 genera (Strelitziana, Devriesia, Articulospora, Derxomyces, Cyphellophora, Trechispora, Kurtzmanomyces, Capnobotryella, Erythrobasidium, Camptophora, Stagonospora, Lachnum, Golubevia) showed a highly significant positive correlation with the content of HupA (p < 0.01). These endophytic fungi may have the potential to promote the biosynthesis and accumulation of HupA in plant. Conclusions This report is the first time to analyze the diversity of endophytic fungi in tissues of H. serrata in different seasons, which proves that there is variability in different tissues and seasonal distribution patterns. These findings provide references to the study of endophytic fungi of H. serrata.

Background Plants maintain the steady-state balance of the mutually beneficial symbiosis relationship of their endophytic fungi through secondary metabolites. Meanwhile endophytic fungi can serve as biological inducers to promote the biosynthesis and accumulation of valuable secondary metabolites in host plants through a variety of ways. The composition and structure of endophytic fungal community are affected by many factors, including tissues, seasons and so on. We studied the community diversity, temporal and spatial pattern of endophytic fungi isolated from the roots, stems and leaves of Huperzia serrata in different seasons. The correlation between endophytic fungi and huperzine A content in plants was analyzed. Results A total of 7005 operational taxonomic units were isolated, and all strains were identified as 14 phyla, 54 classes, 140 orders, 351 families, 742 genera. Alpha diversity analysis showed that the diversity of endophytic fungi in stem and leaf was higher than that in root, and the diversity in summer (August) was lower than that in other months. NMDS analysis showed that the endophytic fungal communities of leaves, stems and roots were significantly different, and the root and leaf communities were also different between four seasons. Through correlation analysis, it was found that 33 genera of the endophytic fungi of Huperzia serrata showed a significant positive correlation with the content of huperzine A (p < 0.05), of which 13 genera (Strelitziana、Devriesia、Articulospora、Derxomyces、Cyphellophora、Trechispora、Kurtzmanomyces、Capnobotryella、Erythrobasidium、Camptophora、Stagonospora、Lachnum、Golubevia) showed a highly significant positive correlation with the content of huperzine A (p < 0.01). These endophytic fungi may have the potential to promote the biosynthesis and accumulation of huperzine A in plant. Conclusions This report is the first time to analyze the diversity of endophytic fungi in tissues of Huperzia serrata from different seasons, which proves that there is variability in different tissues and seasonal distribution patterns. These findings provide references to the study of Endophytic Fungi of Huperzia serrata.