This Small Business Innovation Research Phase I project is to perfect a method using peptide aptamers expressed in plants that appears to work to control certain bacterial plant pathogens in the genus Xanthomonas. The aptamers block function of critical pathogenicity (Pth) proteins that are literally injected by the pathogens into plant cells. The objectives are to 1) select better aptamers for capacity to block disease development by screening for binding to predicted critical regions on the Pth protein and 2) create transgenic citrus plants that express the aptamers for later testing for resistance to citrus canker disease. Phase II funding will be sought to produce and test transgenic rice and common bean plants genetically engineered to produce the aptamers. Three diseases of economic importance to the U.S. are likely to be controlled by this novel genetic mechanism: citrus canker, common bean blight and rice blight. There are no cures, no stable genetic resistance, nor even satisfactory controls for these diseases. The citrus industry and state regulators consider canker control methods to be a top priority. Localized losses of citrus, bean and rice due to these three diseases can be up to 50%, 20% and 100%, respectively. Applications to other diseases are likely by this new gene engineering technology.
