Mechanisms of plant resistance to bacterial pathogens (abstract only)

Citation:Lahaye T., Gürlebeck D., Jordan T., Marois E., Meyer A., Peters K., Schornack S., Szurek B., Bonas U. (2002): Mechanisms of plant resistance to bacterial pathogens (abstract only). Plant Protect. Sci., 38: 244-244.
The Gram-negative bacterium Xanthomonas campestris pv. vesicatoria (Xcv) is the causal agent of bacterial spot disease in pepper and tomato. Both basic pathogenicity in susceptible plants and bacterial recognition in resistant plants are determined by the Hrp type III protein secretion system (TTSS) of Xcv. One of the best studied type III effector proteins in our laboratory is the AvrBs3 protein, which is a member of a large protein family in xanthomonads. Xcv strains expressing AvrBs3 are specifically recognized by pepper plants carrying the resistance gene Bs3 leading to the induction of the hypersensitive reaction (HR). The HR is a rapid, localized programmed cell death reaction resulting in the halt of pathogen ingress. AvrBs3 is a 122 kDa protein with a central domain of 17.5 tandem, nearly identical repeat motifs of 34 amino acids. HR induction in Bs3 plants depends on the presence of nuclear localization signals (NLS) and an acidic activation domain in the AvrBs3 protein. This is in contrast to the recognition of the AvrBs3 homolog, AvrBs4. AvrBs4 is specifically recognized in tomato plants expressing the Bs4 resistance gene. Recent data on the map-based isolation of Bs3 and Bs4 will be discussed.

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