1. Department of Plant Physiology, Institute of Molecular Biology, University of Copenhagen, Oester Farimagsgade 2A, DK–1353 Copenhagen, Denmark (E.A.);
2. Department of Evolutionary Botany, Botanical Institute, University of Copenhagen, Gothersgade 140, DK–1123 Copenhagen, Denmark (L.B.J.);
3. Department of Plant Biology, Uppsala Genetic Center, Swedish University of Agricultural Sciences, Box 7080, S–750 07 Uppsala, Sweden (A.-S.H., J.M.); and
4. Department of Medical Biochemistry and Microbiology, Biomedical Centre, Box 582, Uppsala University, S–751 23 Uppsala, Sweden (L.R.)