松材线虫携带细菌在疫区和寄主中的分布及致病性研究

作者在江苏、上海、广东、安徽、湖北、浙江等疫区 ,采集了呈现松材线虫病典型症状的黑松、马尾松的病样 ,采用病木组织分离法 ,分离获得松材线虫所携带的细菌菌株 2 4株 ,经鉴定 ,2 4株细菌中 ,假单胞菌属有 11株 ,泛菌属有 6株 ,其余有不解糖消化链球菌、河生肠杆菌、乡间步丘菌和粘质沙雷菌 .由此可知 ,假单胞菌和泛菌分布较广 ,在所有采样疫区感染松材线虫病的马尾松和黑松病死木中都能分离到 ,是普遍存在病木组织中松材线虫携带的主要细菌 .致萎活性测定结果表明 :所有假单胞菌属和泛菌属的菌株对无菌黑松切根苗均有致萎活性 .用假单胞菌和泛菌分别与无菌松材线虫混合接种室内无菌黑松苗和野外多年生黑松 ,结果表明 :用细菌单独接种 ,无菌黑松苗和野外黑松均不发病 ,无菌松材线虫单独接种的无菌黑松苗和野外黑松也不发病或发病轻、慢 ,无菌线虫和致萎细菌二者混合接种能使无菌黑松苗和野外黑松发病快且严重 .由此认为松材线虫携带到寄主组织中的假单胞菌和泛菌属的一些种对松材线虫病有明显的协同作用

Distribution and pathogenicitiy of bacteria carried by pine wood nematode in epidemic regions and hosts

bacterial strains were isolated from the diseased pine trees of Pinus thunbergii and Pinus massoniana which were infected by pine wood nematode. Specimen were collected in Jiangsu, Shanghai, Guangdong, Anhui, Hubei and Zhejiang Province. Identification results show that there are 11 bacteria strains in Pseudomonas, 6 strains in Pantoea and the others are Peptostreptococcus asaccharolyticus, Enterobacter amnigenus, Buttiauxella agrestis and Serratia marcescens respectively. The bacterial strains, Pseudomonas and Pantoeu, are isolated from samples collected from both Pinus thunbergii and Pinus massoniana in all provinces investigated. Both Pseudomonas and Pantoeu universally exist on Bursaphelenchus xylophilus in diseased pines, and there is selectivity for pine wood nematodes to carry bacteria. Bioassay results show that both strains of Pseudomonas and Pantoea are phytotoxin producers. The representative bacterial strains were chosen to do experiments of pathogenicity by artificial inoculation indoor and outdoor. The pathogenicity tests show that aseptic seedings and Pinus thunberg wilting diseases do not occur when inoculated with bacteria separately, and wilting diseases do not occur or occur slowly and lightly with aseptic nematode separately. However, rapid wilting disease is observed when inoculated with the mixed suspension of them. The preceding results prove that certain synergism exists between nematode and some species of Pantoeu or Poseudomomas for the disease, and bacteria of Pseudomonas and Pantoeu carried by pine wood nematodes possibly play certain role in pathogenicity of the disease.