The present invention has increased the resistance to drought stress in Poplar by integrating a transgene constitutively expressing a pine superoxide dismutase (SOD) into the plant genome. It is contemplated that this approach to drought resistance improvement will be equally successful for all woody perennials. Provided with the invention is an expression cassette, a vector, and a method for increasing SOD activity in woody perennials, as well as transgenic woody perennials with enhanced drought resistance and accompanying phenotype.
 Pursuant to 35 U.S.C. .sctn.202(c) it is acknowledged that the U.S. Government has rights in the invention described, which was made with funds from the US Department of Energy, Grant No. GO12026-314.