1. Universität Potsdam, Institut für Biochemie und Biologie, Abteilung Molekularbiologie, Karl-Liebknecht-Strasse 25, Haus 20, D–14476 Golm/Potsdam, Germany (B.M.-R.); and
2. Lund University, Department of Plant Biochemistry, P.O. Box 124, SE–221 00 Lund, Sweden (C.P.)