江西烟草青枯病菌的分子鉴定及系统发育分析

Molecular identification and phylogenetic analysis of pathogen of tobacco bacterial wilt in Jiangxi province

从江西省信丰、广昌和峡江3县采集呈典型症状的烟草青枯病株进行病原菌分离,得到3个具有致病性的细菌分离株,分别命名为RSXF-1、RSGC-1和RSXJ-1。采用细菌16S rDNA基因通用引物对3个分离株的16S rDNA基因进行PCR扩增,对扩增产物进行克隆和序列测定,各得到长为1 500 bp的核苷酸序列。经同源性分析,发现3个分离株均为茄科劳尔氏菌(Ralstonia solanacearum),且三者间具有高度的序列同源性。将此3个分离株的16S rDNA核苷酸序列与GenBank中R.solanacearum代表性株系的对应序列进行同源性分析并构建系统发育树,结果表明RSXF-1、RSGC-1和RSXJ-1均与我国广东省和云南省的分离株具有最近的亲缘发育关系。

Diseased samples of showing typical symptoms of tobacco bacterial wilt were collected from three counties of Xinfeng, Guangchang and Xiajiang in Jiangxi province. Three bacterial isolates named RSXF-1, RSGC-1 and RSXJ-1 were obtained respectively from each county sample,and they were proven to been pathogenic. PCR amplification of 16S rDNA gene of the three isolates were conducted by using bacterial 16S rDNA universal primers 27F/1492R. The PCR products were cloned and sequenced, and 1 500 bp nucleotide sequence was determined for each PCR product. The homology analysis showed that all of the three isolates were Ra!stonia solanocearum, and they had a high degree of sequence homology. The 16S rDNA nucleotide sequence of the three isolates were then compared with the corresponding sequence of representative strains in GenBank, and phylogenetic tree was constructed. The results showed that RSXF-1, RSGC-1 and RSXJ-1 were all closely related to R.solanacearum isolated in Guangdong and Yunnan province of China.