Isolated fragments of an Erwinia hypersensitive response elicitor protein or polypeptide that elicit a hypersensitive response in plants and isolated DNA molecules that encode those fragments are disclosed. Isolated fragments of hypersensitive response elicitor proteins or polypeptides, which elicit a hypersensitive response, and the isolated DNA molecules that encode them can be used to impart disease resistance to plants, to enhance plant growth, and/or to control insects on plants, either by applying the hypersensitive response eliciting fragments to plants or plant seeds or by providing transgenic plants or plant seeds transformed with a DNA molecule encoding a hypersensitive response eliciting fragment.