LAUSR

BACKGROUND Potato late blight (PLB) caused by Phytophthora infestans is one of the most devastating plant diseases. The heavy use of chemical control agents is at odds with the development of sustainable and environmentally friendly agriculture practices. It is necessary to screen the antagonistic microorganisms of P. infestans and provide a new choice of PLB biocontrol. RESULTS In vitro, eight bacterial strains (A, B, C, D, E, F, G, H) isolated from the rhizosphere of resistant potato plants had a significant inhibitory effect on the mycelium growth of P. infestans, and the inhibition rate was 35.02 % - 79.20 %. These isolates were assigned to Streptomyces, Pseudomonas, Saccharothrix and Nocardiopsis by phylogenetic analysis of 16S rRNA genes. Their physiological and biochemical characteristics suggested that they can produce cellulase and catalase, which may help to inhibit the infection of P. infestans. In vivo, each strain significantly inhibited the infection of P. infestans after individually inoculated into potato tubers, and no strains posed a pathogenic threat to tubers. In the field environment, multi-bacterial treatment significantly reduced the disease index. Compared with the control, multi-bacterial and single H treatment significantly increased the microbial species and abundance of the potato rhizosphere and enriched potential beneficial bacteria such as Rhizobiaceae. Meanwhile, they significantly reduced the abundance of Enterobacteriaceae and Bacillaceae. CONCLUSION Our results provide some valuable native strains from the potato rhizosphere with the ability to inhibit P. infestans in vivo and in vitro, which may be a new choice of PLB biocontrol.