1. Laboratory of Plant Molecular Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo , 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan
2. Plant Physiology, Institute of Plant Biology and Biotechnology, University of Muenster , Schlossplatz 7-8, Münster D-48149, Germany
3. Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg , Weinbergweg 10, Halle (Saale) 06120, Germany
4. Department of Botany, Graduate School of Science, Kyoto University , Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502 Japan