Screening and Identification of Biocontrol Bacteria for Anthracnose in <i>Mahonia eurybracteata</i> Fedde

Mahonia eurybracteata exhibits characteristics related to heat dissipation, nutritional supplementation, and possesses antimicrobial and anticancer properties. Despite its widespread cultivation through artificial means, the detrimental impact of anthracnose on its growth has led to extensive reliance on chemical pesticides for disease control. Unscientific pesticide application and the use of outdated spraying techniques contribute to the presence of pesticide residues in both plants and the environment, thereby posing potential risks. This study utilized tissue isolation to segregate the pathogenic fungus causing anthracnose. The isolated strains, identified through 18S rRNA, were identified as Colletotrichum fructicola and Colletotrichum gloeosporioides. Koch's postulates were employed to confirm the pathogenicity of these strains. Simultaneously, soil samples from the rhizosphere of healthy M. eurybracteata were collected. Using the dilution plate method, 14 bacterial strains were isolated, and molecular biology techniques were employed for preliminary and subsequent screening via the agar confrontation method. Results indicated that selected strains of Pseudomonas gessardii and Pseudomonas fluorescens exhibited inhibitory effects on C. fructicola and C. gloeosporioides, respectively. Through in vitro detached leaf experiments, the biocontrol effectiveness of these two bacterial strains was validated. This study establishes a theoretical foundation for the development and application of antagonistic bacteria.