关键词: 瓦雷兹芽孢杆菌(YH-20), 根癌农杆菌, 拮抗作用, 解磷作用, 樱花

Abstract:

【Objective】 Solve the problem of cherry root-cancer in cherry plant production. 【Method】 Endophytic bacteria were isolated from the leaves and branches of cherry plants using dilution separation and tissue separation, respectively. Antagonistic bacteria against Agrobacterium tumefaciens were selected by the filter paper method; strains were identified by morphological, physiological and molecular biology methods. The ability of a strain to screen for organophosphate residues was determined by colorimetry. Additionally, the ability of a strain to produce IAA and to resist NaCl was determined using a specific medium and by measuring bacterial density at OD₆₀₀, respectively.【Result】 A total of 32 endophytic bacteria were isolated from cherry plants, 28 of them were isolated from the shoots and 4 from the leaves. All the 32 endophytic bacteria were screened for antibacterial activity and only two strains showed a significant inhibitory effect over Agrobacterium tumefaciens. One of these bacteria, strain YH-20, was identified as Bacillus velezensis. Strain YH-20 also showed that it was capable of solubilizing organic and inorganic phosphorus. The amount of inorganic and organic phosphorus dissolved after 7 days was 178.43 and 76.50 mg/L, respectively. Strain YH-20 also had the ability to secrete IAA; it produced 9.174 μg/mL IAA after 7 days of incubation. B. velezensis strain YH-20 can grow normally on a medium containing 10% NaCl. 【Conclusion】 Therefore, the endophyte, Bacillus velezensis YH-20, obtained through this screening, is an antagonist of A. tumefaciens that has the ability to dissolve phosphorus. Thus, it is a strain with good application prospects in the prevention and treatment of root cancer in the forest.

Key words: Bacillus velezensis, Agrobacterium tumefaciens, antagonism, phosphorus removal, Ceresas