Extracellular polysaccharide from Ralstonia solanacearum; A strong inducer of eggplant defense against bacterial wilt

Abstract

Ralstonia solanacearum a phytopathogenic bacterium produces virulence factor via production of extracellular polysaccharides (EPS). We have isolated EPS from R. solanacearum and characterized this by AFM, SEM, FTIR, LC-MS and NMR spectroscopy. Interestingly, the result showed pore size distribution, topology, rheological and pseudoplastic behaviour of EPS and three major monosaccharides, glucuronic acid, N-acetylglucosamine and glucose associated with EPS. Eggplant treated with intact crude EPS showed a significant 51% decrease in bacterial wilt incidence for both in vitro and greenhouse conditions. In eggplant cultivars EPS induces significant up-regulation of guaiacol peroxidase and ascorbate peroxidase defense genes, providing screen resistance against bacterial wilt.