苹果树腐烂病内生拮抗放线菌A-2的鉴定及其活性评价

以苹果树腐烂病菌Valsa mali为靶标菌,从健康苹果树枝条中获得一株高效内生放线菌A-2。采用生长速率法、对峙培养法和玻片法测定了菌株A-2的抑菌谱及对苹果树腐烂病菌菌丝生长和孢子萌发的影响;利用离体枝条烫伤接种法测定了菌株A-2对腐烂病的防治效果。结果表明:A-2发酵滤液对腐烂病菌的抑制率达90%以上,对其他9种常见的植物病原真菌也具有良好的拮抗作用;菌株A-2可导致腐烂病菌菌丝畸形、分支增多和局部膨大;不同稀释倍数的A-2发酵滤液对苹果离体枝条腐烂病均有明显的防效,接种病原菌前后24 h和同时施用500倍发酵滤液的防效均达70%以上。根据培养特征、生理生化特性和16S rDNA 序列分析,将菌株A-2鉴定为卡伍尔链霉菌Streptomyces cavourensis。

Identification of antagonistic endophytic actinomycetes A-2 and evaluation of its activity against Valsa mali

An endophytic actinomycetes A-2 against Valsa mali was isolated from healthy apple tree branches.The antagonistic spectrum of strain A-2 and its inhibitory activity against the hyphal growth and conidial germination of V.mali were investigated by using plate growth rate,flat confrontation culture and slide method.In addition,the inhibitory activity of strain A-2 against V.mali in detached apple twigs was also determined.The results showed that the inhibition rate of A-2 fermentation supernatant on V.mali could reach more than 90% and it had obvious antifungal activity against V.ambiens and other eight pathogenic fungi.Strain A-2 could induce alteration on hyphae morphology of V.mali,such as deformation and enlargement.Different dilution of strain A-2 fermentation supernatants all showed obvious inhibitory activity against V.mali in detached twigs.The control efficacy was still above 70% when the supernatant was diluted by 500 folds and used before and after inoculation of V.mali.Based on the cultural characteristics,physiological and biochemical properties as well as 16S rDNA sequencing,the strain A-2 was identified as Streptomyces cavourensis.Actinomycets A-2 could be developed new biological pesticide for control of V.mali.