苹果树腐烂病菌拮抗放线菌JPD-1的筛选及鉴定

为筛选对苹果树腐烂病菌Valsa mali具有拮抗作用的放线菌,从苹果树根际土壤中分离获得放线菌,利用平板对峙法和生长速率法筛选拮抗活性较高的菌株,通过菌株培养特征、形态特征、生理生化特性及16S rDNA序列分析确定其分类地位,并采用离体枝条烫伤接种法测定所筛选获得的拮抗菌株对苹果树腐烂病的防效。结果表明,从苹果树根际土壤中共分离获得28株放线菌,其中菌株JPD-1对苹果树腐烂病菌的拮抗作用最强,抑制率为72.50%,该菌在高氏合成1号培养基上生长最好,培养7 d时菌落生长旺盛,气生菌丝白色,基生菌丝深粉红色,无可溶性色素产生;经形态特征观察、生理生化试验及16S rDNA序列分析,将菌株JPD-1鉴定为公牛链霉菌Streptomyces tau‐ricus。菌株JPD-1发酵滤液对苹果树腐烂病菌的抑制率及对离体枝条上苹果树腐烂病的防效均随稀释倍数的增大而减弱,发酵滤液原液使苹果树腐烂病菌菌丝膨大、末端畸形,抑制率为78.14%,对离体枝条上苹果树腐烂病的防效为76.37%。表明分离到的放线菌菌株JPD-1可以用作苹果树腐烂病的生防材料,具有很好的开发及应用前景。

Screening and identification of antagonistic actinomycetes JPD-1 against the pathogen Valsa mali

In order to screen and obtain the antagonistic rhizosphere actinomycetes with significant antifungal activity against the pathogen Valsa mali, the antagonistic rhizosphere actinomycetes were isolated from the rhizosphere soil of apple tree, and the highest antifungal activity of strain was screened by using the methods of dual culture and colony growth. Moreover, the species with the highest antifungal activity was identified according to the cultural characterization, colony morphology, physiological characterization and 16S rDNA sequence. The results showed that the strain JPD-1 presented the significant antifungal activity against V. mali in comparison to a total of 28 strains of actinomycetes isolated from the apple tree rhizosphere, with an inhibitory rate of 72.50%. Meanwhile, the strain JPD-1 could grow better on Gause''s synthetic agar medium:the colony grew well, and the color of aerial hyphae was white, whereas the substrate hyphae were pink at the 7th day after incubation, which did not generate the soluble pigment in the cultural medium. The strain JPD-1 was identified as Streptomyces tauricus according to the cultural characterization, colony morphology, physiological characterization and 16S rDNA sequence. The inhibitory activity of the strain JPD-1 fermentation against V. mali in vitro and apple tree branches was decreased with increasing dilution. The hyphae of V. mali were swelled and deformed at the undiluted fermentation, and the biocontrol effects of strain JPD-1 were 78.14% and 76.37% in vitro and apple tree branches, respectively. The results indicated that the strain JPD-1 could be used for controlling the apple tree Valsa canker in vitro and in vivo, and show a wonderful prospect for development and application in the future.