1. University of Zurich, Department of Plant and Microbial Biology, Zollikerstrasse 107, Zurich 8008 Switzerland
2. Kobe University, Department of Biology, Rokkodai 1-1, Nada-ku, Kobe 657-8501, Japan
3. Faculty of Science and Engineering, Konan University, Kobe, 658-8501 Japan
4. Nagoya University, Graduate School of Bioagricultural Sciences Chikusa, Nagoya 464-8601 Japan