1. Department of Plant Pathology, Michigan State University, East Lansing, Michigan 48824–1311 (M.T., B.D.); Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907–2064 (F.C., C.J.S.); and Department of Genetics, University of Georgia, Athens, Georgia 30602–7223 (D.R.R., R.B.M.)