Plant Pathogenicity Phenotyping of Ralstonia solanacearum Strains.

In this chapter, we describe different methods for phenotyping strains or mutants of the bacterial wilt agent, Ralstonia solanacearum, on four different host plants: Arabidopsis thaliana, tomato (Solanum lycopersicum), tobacco (Nicotiana benthamiana), or Medicago truncatula. Methods for preparation of high volume or low volume inocula are first described. Then, we describe the procedures for inoculation of plants by soil drenching, stem injection or leaf infiltration, and scoring of the wilting symptoms development. Two methods for measurement of bacterial multiplication in planta are also proposed: (1) counting the bacterial colonies upon serial dilution plating and (2) determining the bacterial concentration using a qPCR approach. In this chapter, we also describe a competitive index assay to compare the fitness of two strains coinoculated in the same plant. Lastly, specific protocols describe in vitro and hydroponic inoculation procedures to follow disease development and bacterial multiplication in both the roots and aerial parts of the plant.