五峰马里兰烟空茎病病原鉴定

Identification of Pathogen of Wufeng Maryland Tobacco Hollow Stalk

在实验室对从五峰马里兰烟空茎病病株分离的病原菌进行了形态学观察、致病性鉴定和部分生物学特性研究。结果表明,分离物在LB培养基上的菌落淡黄色,圆形或不定形,表面光滑,微凸起,半透明,边缘整齐。在电镜下观察,菌体短杆状,大小（0.5~1.0）μm×（2.2~3.0）μm,周生鞭毛2~8根,无荚膜,不产生芽孢,革兰氏染色阴性。在结晶紫果胶酸盐（CVP）培养基上产生杯状凹陷。病菌能在5%盐浓度下生长,能在37℃下生长,能利用蔗糖发酵产酸,兼性厌氧,能利用柠檬酸盐,但不能产生吲哚。结合该菌形态学特征、致病性和部分生物学特性,初步确定引起五峰马里兰烟空茎病的病原为胡萝卜软腐果胶杆菌胡萝卜软腐亚种（Pectobacterium carotovora subsp.carotovora）。

The pathogen was isolated from Maryland tobacco in Wufeng county,Hubei province.The morphological characteristics,pathogenicity,and biological characteristics were studied in vitro.After cultivation on LB medium at 28 ℃ for 48 h,the colonies were light yellow,smooth circular or amorphous,small convex,and translucent with neat edge.The isolates was rod-shaped,decapsulated,and gram negative in the size of（0.5~1.0） μm ×（2.2~3.0） μm,with 2~8 flagellum.After cultivation on CVP medium at 28 ℃ for 48 h,the colonies were sunken like a cup.The pathogen was able to grow in 5% NaCl medium at 37 ℃,and produced acid through glucose fermentation.And it was facultative anaerobic,but could not produce indole.Studies revealed that the pathogen was initially identified as Pectobacterium carotovora subsp.carotovora.