DOI: 10.36347/sajb.2013.v01i01.006

Pages: 24-33

Abstract: Plant pathogenic bacteria have evolved specialized strategies to exploit their respective hosts. Most of them are Gram-negative, of which biotropic pathogenic bacteria fundamentally possess a type III secretion system encoded by hrp genes and a variable group of genes encoding Avr effector proteins that seem to be delivered into host plant cells through this pathway to suppress plant defense responses and develop diseases symptoms. An exclusive infection tactic is provoked by Agrobacterium tumefaciens, which genetically transfers its T-DNA from its Ti plasmid to host plant cell via T-pilus belonging to the type IV secretion apparatus. Other key virulence factors of phytopathogenic bacteria are plant cell wall degrading enzymes, phytotoxins, extracellular polysaccharides and phytohormones, which are central for the pathogenesis of necrotrophic bacteria. In general, plant pathogenic bacterial strains mutated in any virulence factor comparatively reduce their virulence, while their pathogenicity remains unchanged. This review summarizes the facts of how bacteria manipulate plant physiology to infect their hosts.