奉新县猕猴桃溃疡病病原菌鉴定

Pathogen Identification of Kiwifruit Bacterial Canker in Fengxin County of Jiangxi Province

为明确江西省奉新县猕猴桃溃疡病病原菌种类。从该县7个猕猴桃生产基地采集呈典型症状的发病枝条和叶片,采用稀释分离法对其进行病菌分离并作致病性测定,共获得27个致病性细菌菌株。对各菌株进行培养性状、形态特征观察和生理生化测定,结果与文献中对丁香假单胞菌猕猴桃致病变种(Pseudomonas syringae pv.actinidiae)的描述相吻合。提取各菌株基因组DNA,分别对其16S rDNA和16S-23S rDNA基因片段进行PCR扩增、测序、序列分析和构建系统发育树,结果各菌株16S rDNA和16S-23S rDNA序列长度均为1 500 bp和280 bp,且菌株间序列完全一致。将获得的两段序列利用Blast程序分别在GenBank中进行同源性搜索,发现其与丁香假单胞菌猕猴桃致病变种同源性均为100%。待鉴定菌株在系统发育树上与该变种处于同一分支。根据实验结果,将奉新县猕猴桃溃疡病的病原鉴定为丁香假单胞菌猕猴桃致病变种。

This paper aims to identify the pathogen of kiwifruit bacterial canker in Fengxin County of Ji- angxi Province.Diseased trunks and leaves with typical canker symptoms were collected from seven kiwifruit production bases in the county.The pathogenic bacteria were isolated from the samples by dilution method and their pathogenicity was tested,and 27 pathogenic bacterial strains were obtained.For each strain,its culture and morphological characteristics were observed and its physiological and biochemical characteristics were de- termined.The results were consistent with the descriptions of Pseudomonas syringae pv.actinidiae(Psa)in the literature.The genomic DNA of each strain was extracted,and the regions of 16S rDNA and 16S-23S rDNA were PCR amplified and sequenced.The sequences were analyzed and used for constructing phylogenetic trees. It showed that the sequence lengths of 16S rDNA and 16S-23S rDNA of all strains were 1 500 bp and 280 bp, and the sequences of the strains were identical.Using blast program,the two segment sequences were searched for homology in GenBank.It was found that they shared 100% homology of either 16S rDNA sequence or 16S- 23S rDNA sequence with Psa.In the phylogenetic trees,the representive strain was grouped together with Psa. Based on the results,the pathogen of kiwifruit bacterial canker in Fengxi County was identified as P.syringae pv.actinidiae.