广西岩溶区烟草黑胫病拮抗细菌的筛选鉴定及其抗病机理

Isolation and identification of antagonistic bacteria and their mechanisms against Phytophthora parasitica var.nicotianae in karst area of Guangxi

关键词:  黑胫病  拮抗细菌  筛选鉴定  抗病机理

Key words:  P.parasitica var.nicotianae  antagonistic bacteria  isolation and identification  anti-pathogeny mechanism

摘要:

从广西岩溶区靖西县优质烟叶生产区分离烟草黑胫病病原及土壤细菌,通过拮抗试验、离体及田间抗病能力测试等方法筛选拮抗细菌; 利用形态观察、生理生化测试和16S rDNA序列分析三种方法相结合,对抗病效果良好的菌株进行分类鉴定; 并对拮抗菌抗黑胫病机理进行初步研究。结果表明:从8份土壤样品中,共分离出土壤细菌340株,获得抗黑胫病效果良好的拮抗细菌3株,编号为8-23、6-70和13,它们分别属芽孢杆菌属、溶菌杆属和假单胞杆菌属细菌; 三个拮抗细菌的抗黑胫病机理是通过胞外分泌一些可溶解病原菌细胞壁的酶或其它化学物质,破坏菌丝的细胞壁和细胞膜等生理结构,使细胞质渗漏、凝集,从而导致病原死亡; 其中,菌株8-23和13的抗病活性物质主要为蛋白质类化合物; 而菌株6-70除蛋白质外,还有其它一些非蛋白因子起作用。

Abstract:

Phytophthora parasitica var.nicotianae and soil bacteria were isolated from Jingxi county,a karst area in southwest of Guangxi province where produced high grade tabacco. Antagonistic bacteria to P.parasitica var.nicotianae were screened out according to their antagonistic action and anti-disease in vitro and field experiment. The well antagonistic effect strains were identified by combining the results of morphological observation,physiological and biochemical characteristics analyse,and 16S rDNA sequence test. And pilot study of the mechanism of anti-disease of P.parasitica var.nicotianae was carried out at the same time. Results showed that a total of 340 strains of bacteria were isolated from 8 samples of soil. And three strians with well antagonistic effect which marked as 8-23,6-70,and 13 were screened out. They were the bacteria belonged to Bacillus,Lysobacter,and Pseudomonas respectively. The mechanism of the three strains against P.parasitica var.nicotianae was to excrete some protein enzymes or other substance which could dissolve the cell wall or membrane of pathogeny and killed them finally. The active substance of strain 8-23 and 13 were mainly protein. But for the strain 6-70,there were some other factors to work besides the protein compounds.