Biocontrol of potato common scab by Brevibacillus laterosporus BL12 is related to the reduction of pathogen and changes in soil bacterial community

Abstract

Potato common scab (PCS) has caused severe economic losses worldwide. Some biocontrol bacteria have been used for effective control of PCS. It was reported that the occurrence of PCS was related to soil microbial community. However, it is still unclear whether soil microbes participate in the disease control by biocontrol agent. Here, Brevibacillus laterosporus BL12 that antagonized PCS pathogen is reported to suppress PCS by reducing pathogen abundance and regulating soil bacterial community. The results of quantitative PCR and high-throughput sequencing demonstrated that the biocontrol strain BL12 stably colonized the tuberosphere soil and rhizosphere soil, and became a keystone species in the bacterial community network of the tuberosphere soil. The application of biocontrol strain BL12 significantly changed the composition and function of bacterial communities in the tuberosphere soil and rhizosphere soil. Some putative beneficial bacteria related to plant disease control such as Pseudomonas and Microbacterium were significantly positively correlated with biocontrol strain BL12, and significantly negatively related to the disease index and/or pathogen. They may cooperate with biocontrol strain BL12 to control PCS. Functional prediction showed that the application of biocontrol strain BL12 significantly increased the relative abundance of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways such as biosynthesis of macrolides, biosynthesis of ansamycins, and biosynthesis of siderophore group nonribosomal peptides, and significantly reduced the relative abundance of nitrogen metabolism and bacterial secretion system. This research provided potential micro-ecological mechanisms for controlling plant diseases with biocontrol agent.