芹菜细菌性软腐病病原的分离与鉴定

由植物病原细菌引起的芹菜软腐病在北京地区普遍发生,其中以顺义及通州区县较为严重。自发病芹菜茎段中分离细菌,通过接种芹菜进行致病性测定,确定了54个致病菌株。虽然菌株间致病力有一定的差异,但大多数菌株对芹菜致病力强。通过培养性状和菌体形态观察、生理生化反应和Biolog测定,结合胡萝卜软腐果胶杆菌Pectobacterium carotovorum6个管家基因(pgi、rpoS、mdh、proA、mtlD、icdA)的基因扩增、序列测定和多基因联合系统发育分析,将病原菌鉴定为胡萝卜软腐果胶杆菌P.carotovorum的3个亚种。其中45个菌株为P.carotovorum subsp.odoriferum,频数为83.33%;6个菌株为P.carotovorum subsp.carotovorum,频数为11.11%;3个菌株为P.carotovorum subsp.brasiliensis,频数为5.56%。上述结果显示,北京地区芹菜细菌性软腐病的病原菌为胡萝卜软腐果胶杆菌P.carotovorum的3个亚种,其中以P.carotovorum subsp.odoriferum为优势种。

Isolation and identification of the pathogen causing celery bacterial soft rot

Celery bacterial soft rot has become severe in Beijing, especially in Shunyi and Tongzhou district. In order to identify the causal agent of the disease, bacterial strains were isolated from the diseased celery stems, and the pathogenicity of the isolates was then confirmed by inoculation of these isolates on celery seedling following Koch's postulation. Fifty-four pathogenic isolates were obtained. Based on morphological observation, physiological, biochemical and Biolog test, as well as multilocus sequence analysis of six concatenated housekeeping gene sequences(pgi、rpoS、mdh、proA、mtlD、icdA), the causal pathogen was identified as Pectobacterium carotovorum. Among these disease-causing isolates, 45 strains were identified as P. carotovorum subsp. odoriferum with a frequency of 83.33%,6 strains as P. carotovorum subsp. carotovorum with a frequency of 11.11%, and 3 strains as P. carotovorum subsp. brasiliensis with a frequency of 5.56%. These results indicate that the causing agents of celery bacterial soft rot in Beijing were identified as three subspecies of P. carotovorum, and P. carotovorum subsp. odoriferum was dominant.