Characterization of the pathogen causing a new bacterial vein rot disease in tobacco in China

• P. carotovorum subsp. carotovorum (Pcc) was the causal agent of tobacco bacterial vein rot.
• The bacteria was identified based on biochemical characteristics and 16s rRNA analysis.
• The typical symptom consisted of main or lateral vein necrosis and leaf dry rot
• This is the first report of Pcc causing tobacco leaf disease in China.

In 2015, red or black-brown necrotic lesions on main or lateral veins associated with the wilting of leaves and dry rot caused by plant pathogenic bacteria were found in tobacco plants in different fields in Shaowu city, Fujian province, China. Two bacteria (FM3 and FM4) were isolated and selected for further tests. Pathogenicity test results showed that all the tested isolates developed typical vein rot symptoms in tobacco 4 days after inoculation and soft rot symptoms in potato tuber, okra, pepper, capsicum, celery, and Chinese cabbage 2 days after inoculation, with the bacterium re-isolated from all the inoculated plants. On the basis of phenotypic properties, maceration characteristics, biochemical tests, Biolog system, and 16S rRNA sequences analysis, isolates FM3 and FM4 were identified as Pectobacterium carotovorum subsp. carotovorum. To our knowledge, this is the first report that the new bacterial vein rot disease in tobacco in Shaowu city, China, was caused by P. carotovorum subsp. carotovorum.