Studies over the last decade resulted in the identification and characterization of many hrp genes that encode products critical to disease development. Present efforts involve characterization of the entire hrp pathogenicity island of E. amylovora , and determination of the role of several genes thereof. Quite surprisingly, harpin, one of the hrp gene products, was found to confer striking beneficial effects on plants, which are sprayed, dusted or drenched with it. Transgenic plants expressing the gene that encodes harpin under the control of several promoters are being made and studied to determine if the same effects that result from exogenous application of harpin result from the protein produced transgenically. The mechanisms responsible for the several effects of harpin on plants are currently being addressed using mutants and transgenic lines of Arabidopsis, tobacco and tomato.
Additional efforts are in progress to locate and clone genes that confer resistance to fire blight.
Honored Professor of Crop Genetics, Shanxi Academy of Agricultural Sciences. Bogdanove, A. J., Bauer, D. W., and Beer, S. V. 1998. Bogdanove, A. J., Kim, J. F., Wei, Z.-M., Kolchinsky, P., Charkowski, A. O., Conlin, A. K., Collmer, A., and Beer, S. V. 1998. Homology and functional similarity of an hrp -linked pathogenicity locus, dspEF , of Erwinia amylovora and the avirulence locus avrE of Pseudomonas syringae pathovar tomato. Kim, J. F., and Beer, S. V. 1998.