Type III Secretion Machinery Has a Role in the Virulence of Soft Rotting Plant Pathogen Erwinia carotovora carotovora

Abstract

Soft rotting Erwinia carotovora ssp. carotovora (Ecc) is a Gram negative plant pathogenic bacterium. As a primary virulence factor Ecc secretes enzymes that cause maceration of the plant tissue (1). Compared to Gram negative non-macerating plant pathogenic bacteria, such as Pseudomonas syringae, Xanthomonas campestris and Ralstonia solanacaerum the invasion method of the Ecc is robust leading to the rapid destruction of the host plant. In the non-macerating plant pathogens a novel hrp (hypersensitivity reaction and pathogenesis) gene cluster has been described as an essential virulence factor, hrp genes encode for a type III secretion machinery which has been found to be common both to animal and plant pathogenic bacteria (2,3). The function of the type III system is to transfer bacterial effector proteins the into host cell. The effects of the transferred proteins are typically such that the host does not recognize it is being invaded or otherwise changing the dynamics of the host cell in favor of the pathogen. Previously no direct evidence of the function of the hrp cluster in the virulence has been shown in the Ecc.