Species Diversity And Bioactivity Of Dark Septate Endophytes In Tundra Plants Of Changbai Mountain

Dark septate endophytes in the rhizospheres of four typical tundra plant in Changbai Mountain were chosen in our study,which included Rhododendron aureum,Rhododendron confertissimum,Vaccinium uliginosum and Dryas octopetala.In August2021,the root samples of related plants were collected from the tundra of Changbai Mountain Nature Reserve,and the colonization observation,species diversity,antibacterial activity of DSE and the effect of seed soaking on plant seedlings were studied,which provided a theoretical basis for further discussion of the development and utilization of DSE fungi in biological control and agricultural production.The main results were as follows:1.Dark septate endophytes were found to colonized the four common plants in the tundra of Changbai Mountain,and the roots of the four plants had the typical characteristics of melanized sptate hphae and microsclertia.2.A total of 10 genus and 12 species of DSE strains were identified by morphological and molecular biology identification.They are Phialocephala fortinii,Alternaria alternata,Epicoccum nigrum,Colletotrichum spaethianum,Alternaria tenuissima,Colletotrichum camelliae,Leptosphaeria sp.,Canariomyces microsporus,Cladosporium cladosporioides,Cadophora sp.,Phoma sp.,Discosia italica.All the above species were DSE strains reported for the first time in alpine tundra habitats in China.3.The DSE fungal community composition of the four tundra species varied,but Phialocephala fortinii was the common species of the four species,and the isolation frequency was high.It is proved that Phialocephala fortinii have no host specificity.Alternaria alternata,A.tenuissima and other strains have also been reported in arid desert habitats,indicating that DSE has a wide ecological distribution.4.Four DSE strains were screened out,which were NP-1,NP-8,NP-13 and XNM-5,and had good inhibitory effects on pathogens of maize leaf blight and leaf Spot on Zanthoxylum nitidum.When the concentration of fermentation filtrate of strain XNM-5(Colletotrichum spaethianum)was 20%,the inhibition rates of strain XNM-5 against the two plant pathogens were the highest,which were 47.83% and 77.99%,respectively.5.When the concentration of XNM-5 fermentation filtrate was 20%,DSE fermentation filtrate had strong allelopathy on Solanum lycopersicum seed germination and seedling growth.It was found that there may be some active substances in the filtrate of DSE fermentation,which can promote the growth of plants,improve the survival rate of seedlings and promote the accumulation of active substances by improving the nutritional conditions of plants,and provide a theoretical basis for the application of DSE in agricultural production.