华石斛内生真菌组织分布特点及其抑菌活性

摘要

植物内生菌种类繁多,且具有较丰富的生物学功能.从海南特有药用植物华石斛(Dendrobium sinense)野生植株中分离内生真菌,初步探索其组织分布特点及抑菌活性.结果表明:从华石斛中分离内生真菌179株,通过ITS序列将之划为51个OTU,分属于25个属以上的类群,其中叶点霉属(Phyllosticta)为优势属.仅轮层炭壳属广泛存在于华石斛根、茎、叶中,其余类群皆存在一定的组织偏好性,其中18个类群只在一种组织中分布.叶中分离的菌株数最多,占比60.33％.不同培养基条件下分离得到的内生真菌种类也存在明显差异,以PDA和华石斛粉培养基分离到的内生菌类群最多,分别为12种,各占总分离类群的48％.12属36个菌株对至少1种供试菌具有抑制效果,其中抑菌生物活性最强的菌株为拟盘多毛孢属(Pestalotiopsis)1株和蓝状菌属(Talaromyces)1株.上述研究结果表明,华石斛内生真菌多样性丰富,部分菌株具有较强抑菌生物活性.这为华石斛内生菌资源的深入开发奠定理论基础,为进一步创制农用杀菌制剂提供依据.%Due to their species and functional diversity,plant endophytic fungi have gradually become a hot topic in current plant biotechnology.In this study,endophytic fungi were separated from an Hainan endemic medicinal plant Dendrobium sinense to explore their diversity,tissue distributing characteristics and antimicrobial funtions,in order to set a foundation for further invention of new agricultural fungicides.The results are presented as following:179 strains of endophytic fungi were isolated and identified as 51 OTUs in 25 taxons based on ITS sequences analysis.Among them,Phyllosticta was the dominant genera.Except Daldinia which widely distributed in roots,stems and leaves,all of the other taxons showed tissue bias.18 taxons only distributed in one kind of tissue.The number of strains isolated from leaves was accounted for the biggest isolation rate of 60.33％.The taxons of endophytic fungi isolated with different kinds of culture medium were varied.Among all of the five culture media,PDA and D.sinense natural medium had the best endophyte capture ability,with 12 taxons (48％ of the total taxon number) being isolated from both of them separately.Antimicrobial activity assay showed that 36 strains in 12 taxons were antagonistic to at least one kind of the testing fungi.One strain of Pestalotiopsis and one strain of Talaromyces showed the strongest antifungal ability.Above all,the diversity of D.Sinense endophytic fungi was very rich.The antifungal bioactivity of some endophyte strains were strong,and worth further study in the future.The results in this study set a foundation for in-depth explosion of endophytic resources of D.sinense.