Ralstonia solanacearum Virulence in Two different Susceptible Hosts by the Leaf Clip Inoculation Method

Ralstonia solanacearum causes the lethal bacterial wilt disease in many plant species across different continents. The systemic infection in a host and broad host range are the unique features of this Gram-negative phytopathogenic bacterium. Under laboratory condition, its virulence is usually studied in grown up plants by inoculation in roots using the soil drenching method. Though virulence functions of the pathogen have been reported well in literature, comparative study of its pathogenicity between different susceptible hosts is not common. One of the limitations might be the complex virulence assay. Recently we established an easy and simple method to study its virulence in early stages of tomato and eggplants seedlings by directly inoculating the pathogen via clipping a part of the cotyledon leaves using a pair of scissors dipped in bacterial suspension. The pathogen could move downward along the shoot from the leaves to the roots in an infected seedling. Importantly, the leaf clip inoculation method assisted in differentiating R. solanacearum virulence functions amidst tomato and eggplant seedlings. This mode of inoculation recruiting young seedlings for virulence assays is instrumental in determining susceptible host range, host specific virulence functions as well as to track pathogenic location corresponding to disease severity.