中文摘要：

为探讨银杏内生细菌对萝卜软腐病的防病作用,通过块根接种和温室盆栽试验筛选对萝卜软腐菌Pectobacterium carotovorum subsp.carotovorum具有高效抑制作用的生防菌株,共获得8株拮抗作用较强的内生细菌,其中菌株Hy11抑菌作用明显。对生防菌株Hy11进行了形态观察、生理生化特性测定、16S rDNA和gyrB基因序列分析,并应用绿色荧光蛋白基因标记菌株Hy11,研究该菌株在萝卜体内的定殖动态。结果显示,该菌株对萝卜软腐病具有较好的防效,对萝卜块根和幼苗的防治效果分别为77.9%和66.7%;对萝卜幼苗的促生率达113.28%。经鉴定,菌株Hy11为解淀粉芽胞杆菌Bacillus amyloliquefaciens。标记菌株Hy11-gfp在喷雾接种银杏叶片后0～3 d种群数量呈急剧下降趋势,10 d后保持相对稳定;其在萝卜的根、茎和叶中均能够定殖,在根中的定殖数量最高可达1.2×104CFU/g。

英文摘要：

In order to study the biological control efficacy of the Ginkgo biloba leaves against Pectobacterium carotovorum subsp. endophytic bacterial strains isolated from carotovorum, the control efficiency of en- dophytic bacteria was screened using the tuber inoculation and pot expermient in green house. The results revealed that 8 bacterial isolates showed strong inhibitory activity, among which strain Hyl 1 suppressed the growth of the pathogen significantly. The strain Hyl 1 was identified according to the morphological, physiological, biochemical characteristics, analysis result of 16S rDNA and gyrB gene sequences. Mean- while, the strain Hyl 1 was labeled with green fluorescent protein gene to investigate its colonization in white radish. The resuhs revealed that the strain Hyll performed good control potential against white radish soft rot disease with 77.9% control efficiency in tubers expermient and 66.7% in pot expermient, respectively. The strain Hyll was also found to promote white radish seedlings growth remarkably with 113.28% growth-promoting effect. The strain Hyll was identified as Bacillus amyloliquefaciens. Thepopulation of strain Hy11-ffp in leaves of G. biloba decreased sharply in the first 3 days after spraying and remained constant level after the 10th day. The strain Hyl 1-ffp could colonize in root, stem and leav- es of white radish seedlings. The colonization amount of the strain Hyl 1-g~ could reach to 1.2 ~ 104 CFU/g in white radish root.