1. Department of Plant Biology, The Carnegie Institution of Washington, 260 Panama Street, Stanford, California 94305 (J.S., C.-W.C., Z.Z., A.R.G.);
2. Biology Department, Duke University, DCMB Box 91000, Durham, North Carolina 27708 (C.H., E.H.H.);
3. Department of Botany, Iowa State University, 353 Bessey Hall, Ames, Iowa, 50011 (J.D., J.M.); and
4. Stanford Genome Technology Center, 855 California Avenue, Palo Alto, California 94304 (R.T.)