西藏青稞根部内生拮抗芽孢杆菌的筛选、鉴定及防病促生特性OA

To obtain biocontrol microbial resources,endophytic bacteria were isolated and purified from highland barley roots by the dilution plate method in this study.2 highly efficient antagonistic endophytic strains were screened via the plate confrontation assay.Their antifungal activities were further evaluated using cell-free fermentation filtrates and volatile compounds.Strain identification was performed based on colony morphology,physiological and biochemical characteristics,as well as sequence analysis of the 16S rDNA and gyrB genes.The results showed that the 2 strains exhibited plate inhibition rates of more than 75%against the three pathogenic fungi.In the test of cell-free fermentation filtrates,the inhibition rates of strain ZDR20 against the three pathogens ranged from 79.45%to 84.69%,and those of strain ZDT27 ranged from 75.25%to 92.98%.Both strains had the strongest inhibitory effect on Pyrenophora graminea.In the volatile antifungal test,the inhibition rates of ZDR20 and ZDT27 against Pyrenophora graminea and Bipolaris sorokiniana were 60.04%and 34.46%,respectively.Neither strain showed inhibitory activity against Fusarium graminearum.Extracellular enzyme assays indicated that both strains could produce 5 kinds of extracellular enzymes including glucanase and protease.Strains ZDR20 and ZDT27 were finally identified as Bacillus amyloliquefaciens.In summary,2 excellent antagonistic endophytic bacteria were successfully obtained in this study,which can provide valuable strain resources and a theoretical basis for biological control of crop diseases and the development of biocontrol agents.