青海省马铃薯软腐病病原菌的鉴定
Identification of Soft Rot Pathogen on Potato (Solanum tuberosum L.) in Qinghai Province

为明确引发青海省马铃薯（Solanum tuberosum L.）软腐病的病原菌，通过对病原菌形态、生理生化特性、16S rRNA基因序列以及胡萝卜果胶杆菌胡萝卜亚种（Pectobacterium carotovorum subsp.carotovorum）的pECC2F序列特征分析，对青海省5个地区马铃薯软腐病病样的病原菌进行病原学鉴定。结果表明，分离的5个菌株均能引发马铃薯软腐病，病原菌鉴定为胡萝卜果胶杆菌胡萝卜亚种。生理生化研究表明，该病原菌菌株均可在37 ℃ 生长，能使明胶液化，具有耐盐性（50 g/L NaCl），对红霉素不敏感，过氧化氢酶反应显示为阳性，蔗糖试验还原反应、氧化酶、磷酸酶活性和吲哚产生试验显示均为阴性，可以利用柠檬酸盐、乳糖、纤维二糖、棉子糖和蜜二糖，但是不能利用D-麦芽糖、山梨醇、D-阿拉伯糖醇和α-甲基葡萄糖。接种马铃薯块茎致病力测定分析表明，亚种内不同地区的菌株间不存在致病力差异。
To identify causal pathogen causing soft rot of potato(Solanum tuberosum L.) in Qinghai province,five strains isolated from five counties in Qinghai were characterized by morphological,biochemical and physiological methods,and analysed 16S rRNA sequence as well as Pcc subspecies pECC2F region.The results indicated that all of the five strains were pathogenic to potato and caused root rot of potato,so we suggest that Pectobacterium carotovorum subsp.carotovorum was the soft rot pathogens on potato (Solanum tuberosum L.) in Qinghai.The physiological and biochemical tests showed the bacterium grown at 37 ℃,caused gelatin liquefaction,represented the tolerance to saltin 50 g/L NaCl solution,and had no sensitivity to erythromycin.The bacterium also gave a positive response to catalase,but negative responses to oxidase,phosphatase activity,indole production,and sucrose reduction reaction.The bacterium utilized some substances including citrate,lactose,cellobiose,raffinose,and melibiose,could not utilize D-maltose,D-sorbitol,D-arabitol,and α-methylglucoside.The pathogenicity tests of all of the bacterial strain collections showed that no significant difference among the same subspecies isolated from different regions was found in Qinghai.