银杏内生细菌防治辣椒疫病研究

从健康银杏植株叶片中分离到108 株内生细菌,通过平板测试从中筛选获得35 株对辣椒疫霉菌Phytophthora capsici具有拮抗作用的菌株.温室盆栽试验证明,菌株 Zy44、Fy11、Hy7、Hy14 和 Zy25 对辣椒疫病防效显著,其中Zy44 和 Fy11 发酵液在辣椒疫霉菌接种 20 d 后防效分别为 62%和 52.33%;经形态观察、生理生化特征测试、16S rDNA序列和gyrB基因序列分析,鉴定这两个菌株为解淀粉芽胞杆菌Bacillus amyloliquefaciens;其发酵滤液及酸沉淀获得的脂肽类抑菌物质对盆栽辣椒苗疫病的防治试验结果表明,菌株 Zy44 的防效高于 Fy11,且脂肽类物质的防效高于发酵滤液;显微镜观察发现菌株 Zy44的脂肽类抑菌物质可导致辣椒疫霉菌菌丝体膨大, 分枝增多, 成簇状,并显著抑制孢子囊的形成.

Inhibition of Endophytic Bacterial Strains Isolated from Ginkgo biloba against Phytophthora Blight of Pepper

108 endopytic bacterial strains were isolated from healthy Ginkgo biloba leaves. Based on screening in vitro, the 35 bacterial isolates showed inhibitory activity against Phytophthora capsici. Tests on 8 isolates to control fruit phytophthora blight of pepper showed that all the isolates could control the disease with various degrees, and the isolates zy44 and Fyll, were found to have the better biocontrol efficacy. Based on characteristics in morphology, physiology, biochemistry, 16S rDNA and gyrB sequence analysis, both strains Zy44 and Fyl 1 were identified as Bacillus amyloliquefaciens. Tests on biocontrol efficacy of cell-free filtrate and lipopetides produced by Zy44 and Fyl 1 to suppress phytophthora blight of pepper in greenhouse indicated that the ones of Zy44 were more highly inhibitive than those of Fyl 1, and lipopetides were more inhibitive than cell-free filtrate. Microscopical observation indicated that lipopetides produced by Zy44 could lead to malformations of hyphae and reduce production of sporangia ofP. capsici.