番木瓜内生细菌MG-Y2的鉴定及其生防作用

为筛选具有防病作用的植物内生菌,采用组织分离法和稀释分离法,分离番木瓜果皮中的内生细菌,得到103个菌株。采用培养基平板抑菌圈测定法从这些菌株中筛选到1株具有拮抗活性的细菌MG-Y2,对番木瓜疫霉病菌(Phytophthora nicotianae)、番木瓜炭疽病菌(Colletotrichum gloeosporioides)等8种病原菌有较强的拮抗作用。通过对其形态特征和生理生化特性测定以及16SrDNA部分序列同源性分析,鉴定该细菌为恶臭假单胞菌生物变种Ⅰ(Psudomonas putida biovarⅠ)。采用喷雾接种处理,MG-Y2可进入番木瓜叶片、叶柄、果皮和果肉中定殖。进行番木瓜果实采后防病试验,MG-Y2对采后番木瓜疫病和炭疽病的防治效果分别达到88.8%和57.4%。试验结果显示MG-Y2具有潜在的生防应用价值。

Identification and biocontrol effect of endophytic bacterial strain MG-Y2 isolated from papaya

In order to select plant endophytes that have biological control effect on plant diseases,103 strains of endophytic bacteria were isolated from papaya pericarp by means of tissue and dilution screening methods. In the dual plate assays,a biocontrol agent strain MG-Y2 which showed the strong inhibiting effect on Phytophthora nicotianae,Colletotrichum higgisianum,Colletotrichum gloeosporioides,Phytophthora capsici,Peronophythora litchi,Alternaria mali,Fusarium oxysporum and Erwinia carotovora was selected from those 103 strains. It was identified as Pseudomonas putida biovar Ⅰ according to the characteristics of its morphological,physiological and biochemical characters and the homology analysis of the partial sequence of 16S rDNA. By spraying inoculating treatment at the stage of young fruit,MG-Y2 could be colonized in the laminae,leafstalk,pericarp and pulp of papaya. In the postharvest disease controll experiment,the strain MG-Y2 showed 88.8% and 57.4% control effect on Phytophthora nicotianae and Colletotrichum gloeosporioides of harvested papaya fruit,respectively. The results suggested that the strain MG-Y2 had potential application value in biological control.