Characterization of the rcsA Gene from Pantoea sp. Strain PPE7 and Its Influence on Extracellular Polysaccharide Production and Virulence on Pleurotus eryngii

RcsA is a positive activator of extracellular polysaccharide (EPS) synthesis in the . The gene of the soft rot pathogen sp. strain PPE7 in was cloned by PCR amplification, and its role in EPS synthesis and virulence was investigated. The RcsA protein contains 3 highly conserved domains, and the C-terminal end of the open reading frame shared significant amino acid homology to the helix-turn-helix DNA binding motif of bacterial activator proteins. The inactivation of by insertional mutagenesis created mutants that had decreased production of EPS compared to the wild-type strain and abolished the virulence of sp. strain PPE7 in . The sp. strain PPE7 gene was shown to strongly affect the formation of the disease symptoms of a mushroom pathogen and to act as the virulence factor to cause soft rot disease in .