1. Department of Botany and Plant Pathology and Center for Gene Research and Biotechnology, Oregon State University, Corvallis, Oregon 97331 (T.M.C., Z.V., K.M.A., J.W.S., J.E.F.); Pioneer Hi-Bred International, Johnston, Iowa 50131 (Y.K.S., R.B.M., J.P.D.); and Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (C.A.A., R.S.Q.)