1. Kihara Institute for Biological Research, Yokohama City University 641‐12 Maioka Totsuka, Yokohama Kanagawa 244‐0813 Japan
2. Faculty of Agriculture Iwate University 3‐18‐8 Ueda Morioka Iwate 020‐8550 Japan
3. Institute of Agrobiological Sciences, National Agriculture and Food Research Organization 3‐1‐3 Kan‐nondai Tsukuba Ibaraki 305‐8604 Japan
4. Genetic Strains Research Center National Institute of Genetics Mishima, Shizuoka 411‐8540 Japan
5. Department of Life Sciences School of Agriculture, Meiji University 1‐1‐1 Higashi‐mita Kawasaki 214‐8571 Japan
6. Research Faculty of Agriculture Hokkaido University Kita‐9 Nishi‐9 Kita‐ku, Sapporo 060‐8589 Japan