Bo Zhang;Shuguang;MIN Min;Dong Sun;Hongxu;Ming Liu;Shenggao;Lixiang Wen;Guanghon

maryland tobacco;pathogen;medium;colonies;wufeng;hollo

The morphological characteristics,pathogenicity and biological characteristics of the pathogen isolated from Maryland tobacco in Wufeng County of Hubei Province were studied in the laboratory. After cultivation on LB medium at 28 ℃ for 48 h,the colonies were light yellow,circular or amorphous,translucent,with smooth and slightly concaved surface and neat edge. Observation under electron microscope showed that 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 flagella. 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; it was facultative anaerobic,and could use citrates,but could not produce indole. It was preliminarily confirmed that the pathogen causing Wufeng Maryland tobacco hollow stalk was Pectobacterium carotovorum subsp. carotovorum.