| Polygonatum cyrtonema,a famous traditional Chinese medicinal herb,is characterized by its fleshy and enlarged rhizome.Modern research has shown that the rhizome contains various active compounds with antioxidant,anti-aging,hypoglycemic,lipid-lowering,and detoxifying properties.However,in recent years,root rot disease has severely affected the yield and quality of P.cyrtonema,hampering the development of its industry.The use of commonly employed chemical agents for disease control fails to meet the requirements of green production,while biological control offers advantages such as minimal pollution,significant control effects,and prevention of pathogen resistance.Previous studies have indicated the presence of abundant endophytic fungi in the rhizome of P.cyrtonema,which represent potential resources for new compounds,drugs,and biocontrol agents.Therefore,this study focused on the rhizome of P.cyrtonema in Qimen County,Huangshan City.The objective was to isolate and identify endophytic fungi from the rhizome at different time points to explore their species diversity.Additionally,pathogenic fungi causing root rot in P.cyrtonema were isolated and identified.Furthermore,potential antagonistic strains with anti-fungal activity against root rot pathogens were selected from the endophytic fungi,and their metabolites were preliminarily analyzed.The main results of this study are summarized as follows:(1)A total of 182 endophytic fungi were isolated from the rhizome of P.cyrtonema,belonging to 2 phyla,5 classes,14 orders,30 families,37 genera,and 55 species.Three fungi could not be classified.Ascomycota was the dominant phylum,with an isolation frequency of 84.07%.Sordariomycetes was the dominant class,with an isolation frequency of 59.89%.Hypocreales was the dominant order,with an isolation frequency of 46.70%.The dominant family was Clavicipitaceae,with an isolation frequency of 33.52%.The dominant genus was Metapochonia,also with an isolation frequency of 33.52%.The study on species diversity revealed a rich diversity of endophytic fungi in the rhizome of P.cyrtonema in Qimen County,Huangshan City.The community structure was complex,and the Shannon-Wiener index,Pielou’s evenness index,Simpson’s dominance index,and richness index of endophytic fungi in the rhizome were higher in spring than in summer.(2)Through a combination of morphological and molecular biological methods,a total of 9 new species were described: 1 belonging to Tolypocladium,3 to Neosetophoma,1 to Phaeosphaeria,1 to Neptunomyces,1 to Peroneutypa,1 to Pezicula,and 1 to Peniophora.Moreover six pathogenic fungi were isolated from P.cyrtonema rhizomes affected by root rot.Through morphological and molecular biological methods,as well as Koch’s postulates,the pathogenic fungi were identified as Fusarium oxysporum.(3)Nine antagonistic strains were selected through dual-culture assays,and their inhibitory activities were tested using the agar diffusion method with fermented broth and mycelial extracts.The results showed that strain HJ202103-53 fermented broth of Penicillium citrinum and strain HJ202103-70 mycelium of Neofusicoccum parvum exhibited the highest inhibition rates of 61.04% and 89.41%,respectively.(4)The metabolites of the antifungal strains were analyzed by HPLC-MS.The results showed that the metabolites were rich in species,and 18 compounds were speculated,some of which had antifungal activity.This study provides a comprehensive assessment of species diversity among endophytic fungi in the rhizomes of P.cyrtonema,identifying nine new species.The findings contribute to our understanding of the community structure and ecological functions of endophytic fungi in P.cyrtonema rhizomes.The isolation and identification of pathogenic fungi associated with root rot disease provide valuable insights for disease management.Moreover,the selection of antagonistic strains and their metabolites with antifungal activity offers potential resources for biological control of root rot. |
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