1. National Agricultural Research Center for Tohoku Region, National Agriculture and Food Research Organization, Morioka, 020-0198, Japan
2. Institute of Geography Science and Natural Resources, Chinese Academy of Sciences, Beijing, 100101, P. R. China
3. Division of Bioresources and Product Science, Hokkaido Univ, Sapporo, 060-8589, Japan
4. Division of Crop Improvement, Central Potato Research Institute, Shimla, 171001, India