Abstract: Northwest China is an important potato producing area in China, so to identify tuber soft rot and stem black leg pathogens of potato (Solanum tuberosum L.) in Qinghai, Gansu, Ningxia, Shaanxi and Inner Mongolia, this paper constructed phylogenetic tree from 28 standard potato tuber soft rot and stem blackleg pathogen strains and 48 pathogenetic strains isolated from 5 provinces in China based on the 16S rDNA gene sequences. Pathogenic bacterial strains isolated from infected potato tuber and stem collected from 5 provinces were identified based on their morphological and cultural characteristics, biochemical and physiological methods, 16S rDNA sequences as well as subspecies/species region analysis. Pathogenicity difference among disease-causing isolates was analyzed by potato tuber inoculation method. The pel specific primers showed that all the 48 bacterial strains have pectolytic characteristics. 16 strains were identified as Pectobacterium carotovorum subsp. carotovorum with a frequency of 31.25% and 30 strains as Pectobacterium atrosepticum with a frequency of 64.50%. Phylogenetic analysis of the 16S rRNA gene sequence showed that Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum isolates clustered together with those identified in other parts of the world with 97% and 99% bootstrap support values, respectively. Pathogenicity assays using isolated representative strains showed varied levels of tuber maceration ability. Aggressive of Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum isolated strains were less than that of the standard strains. These results indicated that the causing agents of potatoes in Northwest region were identified as Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum.

Key words: Solanum tuberosum L., identification, pathogenicity, Pectobacterium spp., northwest region

摘要： 西北地区是我国马铃薯的重要产区，为了鉴定来自青海、甘肃、宁夏、陕西和内蒙古自治区的马铃薯软腐和黑胫致病菌，利用 16S rDNA序列对来自中国 5个省（自治区）的 48 株马铃薯致病菌株和28株参比菌株进行系统发育分析。基于菌株的形态学特性、培养性状和生理生化特性、16S rDNA 序列以及特殊基因序列分析进行鉴定，利用块茎接种法测定不同菌株之间的致病性差异。pel特异性引物表明，48株细菌均具有果胶溶解特性。其中16个菌株为胡萝卜果胶杆菌胡萝卜亚种（Pectobacterium carotovorum subsp. carotovorum），频数为31.25%，30个菌株为黑腐果胶杆菌（Pectobacterium atrosepticum），频数为64.50%。16S rRNA基因序列的系统发育分析表明，Pectobacterium carotovorum subsp. carotovorum与Pectobacterium atrosepticum分别与其他Pcc和Pa菌株聚集成明显的类群，自举支持值分别为97%和99%。致病性测定显示不同分离菌株浸渍块茎的水平不同。分离的Pcc和Pa菌株的块茎浸渍水平低于标准菌株。西北地区马铃薯软腐和黑胫的病原菌分别为Pectobacterium carotovorum subsp. carotovorum与Pectobacterium atrosepticum。

关键词: 马铃薯, 鉴定, 致病性, 果胶杆菌属, 西北地区