Virulence strategies of plant pathogenic bacteria

Plant pathogenic bacteria have evolved several unique virulence strategies to successfully infect their hosts. One current area of intense research in the field of plant-pathogen interactions is the identification and characterization of pathogen virulence factors and the elucidation of their mode of action within the host. This chapter summarizes recent progress in this area of research, focusing on four Gram-negative bacterial pathogens that grow on living tissue and cause primarily leaf spotting or wilt diseases of plants: Pseudomonas syringae, Xanthomonas campestris, Ralstonia solanacearum, and Erwinia amylovora, the causal agents of leaf spots, leaf blights, vascular wilts, and fire blights, respectively. The focus is on these pathogens because significant progress has been made in recent years toward elucidating the molecular mechanisms underlying their virulence. The recently available genome sequence data of various strains of several of these pathogens have also begun to provide additional insight into their virulence strategies. Further, because several of these pathogens can infect Arabidopsis thaliana, use of molecular and genetic approaches to investigate the mode of action of pathogen virulence factors within this host has significantly contributed to our understanding of the virulence strategies of these plant pathogenic bacteria.