Diversity of Ralstonia solanacearum Strains on the Andaman Islands in India

Abstract

Fourteen Ralstonia solanacearum strains from solanaceous vegetables on the Andaman Islands, India, were characterized using a polyphasic approach. The strains wilted their respective hosts within 1 to 3 weeks postinoculation. Virulence assays on tomato (Solanum lycopersicum), brinjal (eggplant; S. melongena), and chili pepper (Capsicum annuum) revealed that all strains were infective on all three hosts. However, tomato was more susceptible than eggplant and chili pepper. Strains were identified as R. solanacearum based on carbon substrate utilization profiling with Biolog similarity coefficients >0.82. Species identity was further confirmed by 16S ribosomal RNA and recN gene sequence analysis. Intraspecific identification of strains revealed the presence of race 1 biovar 3 and race 1 biovar 4. Both biovars wilted plants with similar aggressiveness. All strains were identified as phylotype I, and multilocus sequence typing revealed that the strains belong to a small number of clonal complexes that also comprise strains from mainland India, especially West Bengal state and Kerala.