Glucose-6-phosphate dehydrogenase is required for extracellular polysaccharide production, cell motility and the full virulence of Xanthomonas oryzae pv. oryzicola.

Glucose-6-phosphate dehydrogenase (Zwf) catalyzes conversion of glucose 6-phosphate into gluconate 6-phosphate for Entner-Doudoroff (ED) and pentose phosphate pathways in living organisms. However, it is unclear whether the Zwf-coding gene is involved in pathogenesis of phytopathogenic bacterium. In this report, we found that deletion mutation in zwf of Xanthomonas oryzae pv. oryzicola (Xoc), led the pathogen unable to effectively utilize glucose, sucrose, fructose, mannose and galactose for growth. The transcript level of zwf was strongly induced by glucose, sucrose, fructose, mannose and galactose than that by the NY medium (non sugar). The deletion mutagenesis in zwf also altered the transcript level of key genes, such as rpfF, rpfG and clp, in diffusible signal factor (DSF)-signaling network. In addition, the deletion mutation in zwf impaired bacterial virulence and growth capability in rice leaves, reduced bacterial cell motility and extracellular polysaccharide (EPS) production. The lost properties mentioned above in the zwf deletion mutant were completely restored to the wild-type level by the presence of zwf in trans. All these results suggest that zwf is required for the full virulence of Xoc in rice leaves by involving carbohydrate metabolisms that impact bacterial DSF-signaling network.