The present invention relates to isolated DNA molecules that encode proteins or polypeptides which elicit a hypersensitive response in plants. One aspect of the present invention involves an isolated DNA molecule that encodes the HopPtoP protein of Pseudomonas syringae pv. tomato DC3000. The isolated DNA molecules can be used to impart disease resistance, stress resistance, and enhanced growth to plants or plants grown from treated seeds, to control insects on plants or plants grown from treated plant seeds, to impart post-harvest disease or desiccation resistance in fruits or vegetables, to impart enhanced longevity of fruit or vegetable ripeness, to impart desiccation resistance to cuttings of ornamental plants, and/or promote early flowering of ornamental plants, either by topical application of the proteins or polypeptides or transgenic expression in recombinant plants or plant seeds. Expression vectors, host cells, and transgenic plants which include the DNA molecules of the present invention are disclosed.