1. Department of Biology, Faculty of Sciences, Kyushu University, Ropponmatsu, Fukuoka 810-8560, Japan, Institute of Plant Biology, Biological Research Center of Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France, Biological Laboratory, Faculty of Education, Kumamoto University, Kurokami, Kumamoto 860-0862, Japan, and Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8601, Japan