植物内生细菌在辣椒体内的定殖动态及对辣椒疫病的防治效果

为了探讨具生防作用的植物内生细菌在辣椒体内的定殖动态与其防治辣椒疫病的关系，采用对峙培养法和盆栽苗防效法筛选生防菌株，依据菌体形态、生理生化性质和16SrDNA序列鉴定菌种，用抗利福平标记研究菌株在辣椒苗中的定殖动态，在同时接入植物内生细菌和灌根接种辣椒疫霉菌的条件下分析生防菌株的定殖数量与防效的关系。结果表明，菌株G9、R15和J13对辣椒疫病防效最好，经鉴定均为荧光假单胞菌Pseudomonasfluorescens。菌株G9和R15在辣椒根部定殖量高于菌株J13；定殖周期均在30-40d，呈“先增后减”的变化趋势；菌株G9和R15在接种第15d时定殖量最高，菌株J13在根、茎和叶中定殖量达到最高的天数分别为第9、15和15-20d，定殖数量的变化为根〉茎〉叶。菌株G9定殖量达到9．73×10^5cfu·g-1时辣椒疫病的防效达到100％，保持该数量的时间约6d；菌株R15定殖量达到6．30×10^5cfu·g-1以上时对辣椒疫病的防效达到100％，保持该数量的时间约14d。研究结果展现了植物内生细菌在辣椒疫病生物防治上的应用潜力，为制定植物内生细菌防治辣椒疫病的施用技术提供了科学依据。

Colonization Dynamics of Endophytic Bacteria in Capsicum annuum and Their Control Effects on Pepper Phytophthora Blight

In order to clarify the relationships between colonization dynamics of endophytic bacteria and the control effects on pepper Phytophthora blight, endophytic bacterial strains were screened by dual culturing against Phytophthora capsici and control effects were measured on the potted seedlings. The endophytic bacteria were identified based on their morphological characteristics, biochemical characteristics and 16S rDNA sequence BLAST. Colonization dynamics of endophytic bacteria in seedlings of Capsicum annuum were also conducted by rifampicin labelling and their relationships with control effects were analyzed. The results showed that three endophytic bacterial strains G9, R15 and J13 had obvious control effects against P. capsici and they were identified as Pseudomonasfluorescens. The strains G9 and R15 could colonize in roots of C. annuum, and J13 could colonize in roots, stems and leaves. Colonization periods of three strains were 30--40 d, and their colonization trended to increase firstly and then decrease. The strains G9 and R15 appeared the highest colonization quantity at 15 d after inoculation. The highest colonization quantity of the strain J13 in roots, stems and leaves presented at 9, 15, 15--20 d after inoculation, respectively, with quantity in root 〉 stem〉 leaf. The control effect reached 100% and kept for 6 d under the quantity of 9.73 ×10^5 cfu-g-1 in strain G9, and it reached 100% in strain RI5 under quantity of more than 6.30 × 10^5 cfu.g-1, which could keep for 14 d. Our research suggested that the 3 endophytic bacteria had great potentials in biocontrol applications on pepper Phytophthora blight.