Abstract:

The objectives of this study were to clarify the multi locus sequence typing (MLST) of tobacco wildfire pathogen, and provide strong technical support for formulating effective control measures and breeding varieties, and a new perspective for biological characteristics study of the pathogen. Wildfire disease samples were collected from five tobacco production areas in Hunan, Chongqing and other provinces (Municipalities). And then tissue isolation and identification were carried out. MLST typing was applied to screen housekeeping gene, and the genetic diversity of the tested strains was analyzed. The results showed that 144 strains of tobacco wildfire pathogen were isolated from five tobacco producing provinces (Municipalities). Three housekeeping gene, Pgi, Pfk, and Gap were screened, and a total of 92 ST genotypes were obtained. Using the Pgi gene as the standard, the tested strains could be divided into 5 subgroups, 4 single groups, with a large number of subgroup 1 and subgroup 2 strains. The subgroup 1 strains came from 5 tobacco producing provinces (Municipalities), and ST43 of this subgroup belonged to the main population in China. It indicated that the genetic polymorphism of tobacco wildfire pathogens in China was rich, and there was no correlation between tobacco varieties and pathogen groups.

Key words: tobacco wildfire disease, clove pseudomonas tobacco pathogenic variant, genetic diversity, multi locus sequence typing, subgroup