抗生素2,4-二乙酰基间苯三酚作为荧光假单胞菌2P24菌株生防功能因子的实证分析

Experimental Evidence on The Functional Agent of 2,4-diacetylphloroglucinol in Biocontrol Activity of Pseudomonas fluorescens 2P24

荧光假单胞杆菌 2P2 4菌株分离自小麦全蚀病自然衰退土壤 ,它是酚类抗生素 2 ,4 二乙酰基间苯三酚 (2 ,4 DAPG)的高产菌 ,对多种土传病害具有较好的防治能力。利用同源重组构建 2 ,4 DAPG合成基因的定位突变体 ,并对突变体进行基因互补 ,通过检测突变菌株和恢复突变菌株抗生素产量和生防效果确定 2 ,4 DAPG在菌株 2P2 4生防功能中的作用。实验中 ,定位突变体丧失产生抗生素和拮抗病原菌的能力 ,而恢复突变体的抗生素产量和拮抗能力均恢复至野生菌水平。在对番茄青枯病的防病试验中 ,2 ,4 DAPG突变体的防效低且下降快 ,而恢复突变体的生防能力与野生菌相当 ,且效果稳定。由此可确定 2 ,4 DAPG是菌株 2P2 4防治番茄青枯病的主要因子 ,在防效上起关键作用。

Pseudomonas fluorescens 2P24, a plant disease biocontrol agent isolated from wheat take-all decline soil, is characterized with efficient production of antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG). In this study, the 2,4-DAPG was investigated as a functional agent in antibiosis and biocontrol activity using genetic methods. A 2,4-DAPG negative mutant of P. fluorescnes 2P24, named 2P24MP-ME, was constructed through site-directed mutangensis. The mutant was unable to inhibit the growth of plant pathogens Gaeumannomyces graminis, Rhizoctonia solani and Ralstonia solanacearum in Petri dish and to control the development of tomato bacterial wilt in greenhouse. A plasmid-bearing 2,4-DAPG biosynthetic locus inserted into 2P24MP-ME resulted in a complemented strain 2P24-P. The restored 2,4-DAPG production and strong antibiosis against the phytopathogens were observed in the 2P24-P. Moreover, the efficacy of the 2P24-P for control of tomato bacterial wilt was also recovered to the level of the wild type in the greenhouse. The results indicate that the 2,4-DAPG was one of the key biocontrol factors in P. fluorescens 2P24 and played an important role in controlling tomato bacterial wilt.