Abstract: The difference of distribution and virulence of Ralstonia solanacearum Smith in the plant was investigated to preliminary discuss the relationship between the pathogen and the plant from the point of view of niche. The results showed that the average contents of R. solanacearum in the infected plants of tomato and eggplant (> 100×108 cfu/g) were significantly higher than in those of tobacco, peanut and ginger (< 70×108 cfu/g). The distribution of R. solanacearum was root> stem above middle part > stem below middle part in tomato, reduced gradually from root to top stem in eggplant and peanut, was significantly higher in root and middle stem than low and top stems in tobacco, and was higher in low stem than tuber and stem above middle. The average of attenuation indexes in the infected plants of different host plants were descending in turn as eggplant > tobacco > peanut > ginger; according to the standard of attenuation index, the pathogen from ginger exhibited as virulent strain with attenuation index of 0.49 (< 0.60), while that from eggplant was close to avirulent strain with attenuation index of 0.80 and those form tobacco, peanut and tomato belonged to strain of uncertain virulence with attenuation index of 0.64-0.70. When both healthy and infected plants of eggplant, ginger and peanut were tested, only peanut had R. solanacearum in the two kinds of plants with different infection status. At three disease stages, all the amounts of R. solanacearum in low stem of eggplant were higher than in middle and top stems; the content at different parts all reduced while the course of disease developed from initial stage to middle stage, but no significant difference was found between middle and later stages. The pathogeny didn’t display obviously virulent in the plants of eggplant at different disease stage, but the attenuation index reduced as the disease developed which suggested that the virulence increased.

Key words: Ralstonia solanacearum, plant, distribution, virulence