Screening and inhibitory effect of antagonistic endophytic bacteria associated with soybean root nodules against Magnaporthe grisea

Abstract:

[Objective] Strains were screened from endophytic resources of soybean root nodules in Henan province against Magnaporthe grisea, and researched its inhibitory effect in order to provide the species resources for further study inhibitory mechanism. [Methods] Taking Magnaporthe grisea as tested pathogens, the endophytic bacteria were characterized by antagonistic tests with confront method, the phytopathogen hyphae were analyzed by microscopic observations, the obvious features of antagonistic strains were determinated by cell morphological observation, physical and biochemistry characteristics, 16S rRNA gene sequencing, phylogenic analysis and biological control effect tests. [Results] A total of 17 strains have obvious antagonitic effect by secondary screening, the highest inhibition rate reach 62.16%. Results of microscopic analysis on pathogen hyphae showed that hyphae appear bend knot, fracture, protoplasm concentration, deformity and so on. Interestingly, endophytes rapidly grew to form biofilms on plate during antagonitic screening, and embed hyphae and make it break. Combined with the colony characteristics, physical and biochemistry characteristics and phylogenetic analysis, antagonistic strains were distributed in seven genera and nine species, so antagonistic endophytic bacteria against rice blast possessed species diversity. Control effect tests suggested that rice seedlings incidence and disease index of treatment group with endophytes are significantly lower, biological control efficiency reach up to 74.19%. [Conclusion] Diverse strains were screened from endophytic resources of soybean root nodules against Magnaporthe grisea, rice seedlings incidence and disease index of treatment group with endophytes are significantly lower, biological control efficiency reach significant, it provided species resources for further study inhibitory mechanism.