1. Molecular Plant Sciences Program (A.L.H., C.M.S.) and Department of Crop and Soil Science (C.M.S.), Washington State University, Pullman, Washington 99164–6420; United States Department of Agriculture-Agricultural Research Service, Wheat Genetics, Quality, Physiology, and Disease Research Unit (C.M.S.), Pullman, Washington 99164–6420; and University of Tsukuba, Gene Research Center, Tsukuba, Japa