LAUSR

Ralstonia solanacearum is a phytopathogenic bacterium that colonizes the xylem vessels of host plants leading to a lethal wilt disease. Although several studies have been undertaken on R. solanacearum virulence using adult host plants, infection studies at the seedling stages of hosts by this pathogen are less common. In a preliminary observation, inoculation of R. solanacearum F1C1 on 6 to 7 day old tomato seedlings by a simple ‘leaf-clip’ strategy resulted in a lethal pathogenic condition in seedlings that eventually killed these seedlings within a week post-inoculation. This prompted testing of the effect of this inoculation technique in seedlings from different cultivars of tomato and similar results were obtained. Colonization and spread of the bacteria throughout the infected seedlings could be demonstrated using a gus marked R. solanacearum F1C1 strain. Ralstonia solanacearum GMI1000 strain was also found to be virulent on tomato seedlings using the same inoculation technique. Independent mutants of the R. solanacearum GMI1000 strain deficient in the important virulence functions hrpB, hrpG, phcA and gspD genes respectively were also found to be non-virulent on tomato seedlings when inoculated by this strategy. The leaf clip strategy for tomato seedling inoculation discussed here has the potential to be a valuable approach with respect to time, space, labour savings and costs. This article is protected by copyright. All rights reserved.