Analysis of physiological polymorphism of Chinese Tobacco strains of Ralstonia solanacearum

A collection of 41 Ralstonia solanacearum (RS) strains isolated from bacterial wilted tobacco collected in 10 Chinese provinces was investigated based on their biovar, heterogeneity within an axenic laboratory culture, and growth to determine the current distribution pattern of tobacco RS strains in China as well as to provide theoretic guidance to disease control. Of the 41 isolates, 18 belonged to typical biovars (bv1:1, bv2:4, bv3:10, and bv5:3) and 23 to atypical biovars. This classification was based on their ability to oxidize three hexose (lactose, maltose, and cellobiose) and three disaccharides (manitol, sobitol, and dulcite). Of the 23 strains in atypical biovars, a group closed to bv3 (utilized all the other five carbon sources except dulcite) accounted for 73.9%. Heterogeneity within an axenic culture determined through flow cytometry was initially used for RS. The results showed that the descending order rates of heterogeneity index were 19.5, 24.4, 31.7, and 24.4%, respectively. Growth of different strains in static culture showed that the rates of absorbance value from strong to weak were 58.3, 31.7, and 10%, respectively. All the results above showed that the physiological characteristics of RS strains isolated from different geographical regions were diverse