1. DuPont Nutrition and Health, Experimental Station, Wilmington, Delaware 19880–0402 (E.B.C., K.L.S., S.E.H., A.J.K.); and
2. National Research Council of Canada, Plant Biotechnology Institute, 110 Gymnasium Place, Saskatoon, Saskatchewan, Canada S7N 0W9 (E.-F.M., D.C.T.)