The Research of Antagonistic Endophytic Bacterium Bacillus velezensis CSUFT-BV4 for Growth Promotion and Induction of Resistance to Anthracnose in Camellia oleifera

( ) is one of the four main, woody, edible oil tree species in the world, while anthracnose is mainly caused by the fungus ( ), which severely affects the yield of and the quality of tea oil. ( ) CSUFT-BV4 is an antagonistic endophytic bacterium isolated from healthy leaves. This study aimed to investigate the biocontrol potential of strain CSUFT-BV4 against anthracnose and its possible functional mechanism, and to determine its growth-promoting characteristics in host plants. In vitro, CSUFT-BV4 was shown to have efficient biofilm formation ability, as well as significant functions in the synthesis of metabolic substances and the secretion of probiotic substances. In addition, the CSUFT-BV4 fermentation broth also presented efficient antagonistic activities against five major anthracnose pathogens, including , , , , and , and the inhibition rate was up to 73.2%. In vivo, it demonstrated that the growth of treated with CSUFT-BV4 fermentation broth was increased in terms of stem width, plant height, and maximum leaf area, while the activities of various defense enzymes, e.g., superoxide dismutase (SOD), phenylalanine aminotransferase (PAL), and polyphenol oxidase (PPO), were effectively increased. The remarkable antagonistic activities against anthracnose, the growth-promoting characteristics, and the induction of host defense responses indicate that endophytic bacterium CSUFT-BV4 can be effectively used in the biological control of anthracnose in the future, which will have a positive impact on the development of the industry.