In this study,endophytic fungal diversity of the host plant Sinopodophyllum hexandrum(Royle) Ying was investigated at five locations in Qinghai,Gansu,and Sichuan Provinces.The endophytic fungi on the stems and leaves of the host plants were isolated on two culture media,potato dextrose agar (PDA) and Sabouraud dextrose agar (SDA),and the strains were identified using morphological and molecular analyses.A total of 141 endophytic fungi were isolated from 720 tissue samples.These fungi were divided into 52 endophytic taxa on the basis of their morphology in the culture media.Phylogenetic analysis based on the internal transcribed spacer region indicated 19 genera,18 of which belonged to Ascomycetes and 1 to Basidiomycetes.The number of genera varied among the five locations:10 were detected in Ruoergai County,6 in Datong County,6 in Ledu County,5 in Huangzhong County,and 5 in Xiahe County.With respect to tissue type,16 genera were isolated from the stems,6 from the leaves,and only 3 were found in both tissues.Further analysis showed that Paecilomyces was the most dominant genus,with an isolation frequency of 26.34%,followed by Leptosphaeria,with an isolation frequency of 14.89%.The community structure clearly differed among the locations.At the sites in Xiahe County,Datong County,and Ledu County,the dominant genus was Paecilomyces and the isolation frequencies were 42.31%,56.52%,and 33.33%,respectively.The dominant genus was Leptosphaeria in Ruoergai County and Septoria in Huangzhong County,with isolation frequencies of 26.83% and 38.10%,respectively.Shannon's diversity index ranged from 0.71 to 1.41 and was the highest in Ruoergai County and the lowest in Huangzhong County.Sorenson similarity index ranged from 0.13 to 0.50;it was the highest between Datong County and Ledu County and the lowest between Ruoergai County and Huangzhong County.The colonization rate of the endophytic fungi at the five locations ranged from 14.58% to 28.47%;the mean colonization rate was 19.58%,and the highest colonization rate was observed in Ruoergai County and the lowest colonization rate in Huangzhong County.In addition,the colonization rate was higher in SDA (21.67%) than in PDA (17.50%) and higher in the stem (29.72%) than in the leaf (9.44%).These findings revealed that the species diversity of the endophytic fungi in the stem and leaf tissues of S.hexandrum was low,but the community structure of S.hexandrum differed substantially among the sampling sites.Endophytic fungi that colonize stem and leaf tissues are targets for the production of podophyllotoxin and other natural compounds and,accordingly,have potential practical applications.This study offers a novel strategy for identifying valuable microbial strains from S.hexandrum.