甘肃省嘉峪关市洋葱鳞茎软腐病病原鉴定

Pathogen identification from soft rot disease of onion bulbs in Jiayuguan,Gansu province

结合形态学与分子生物学特征对甘肃省嘉峪关市洋葱鳞茎软腐病病原种类进行了鉴定,在KB培养基上对两株典型菌株的菌落形态和培养特征进行了观察和描述,16SrDNA序列测定和同源性比对结果表明两菌株的16SrDNA序列分别与GenBank数据库已知胡萝卜软腐果胶杆菌胡萝卜亚种和格氏沙雷氏菌的序列同源性均达99%,其片段大小分别为1 386bp和1 379bp。致病性测定结果表明,2种菌均能引起洋葱鳞茎软腐病,且洋葱基部的发病程度高于顶部,其中胡萝卜软腐果胶杆菌胡萝卜亚种的致病力强于格氏沙雷氏菌。按柯赫氏法则初步确定甘肃省嘉峪关市洋葱鳞茎软腐病病原种类为胡萝卜软腐果胶杆菌胡萝卜亚种和格氏沙雷氏菌2种,由格氏沙雷氏菌引起的洋葱鳞茎软腐病属首次报道。本研究将为洋葱软腐病的防治提供理论依据。

A severe soft rot disease of onion （Allium cepa） bulbs occurred in Jiayuguan, Gansu province. The causal agent was isolated and identified based on morphological characteristics of two strains on KB culture me- dium and on molecular characters. The 16S rDNA region of the two strains had homoeology with the known species Serratia grirnesii and Pectobacterium carotovorurn subsp, carotovorum from the GenBank database. The sequence lengths were 1 379 bp and 1 386 bp, respectively with a maximum similarity of 99%and 100%. Both strains caused soft rot disease on onion bulbs in pathogenicity tests. The disease index from roots was higher than that from the tops and P. carotovorum subsp, carotovorurn was more pathogenic than S. grirnesii. The pathogens causing soft rot disease on onion bulbs in Jiayuguan, Gansu province were P. carotovorum sub- sp. carotovorurn and S. grimesii. This is the first report of S. grimesii causing soft rot disease on onion bulbs and this study should provide a theoretical basis for controlling this disease.