1. Graduate School of Life and Environmental Sciences, University of Tsukuba
2. Present address: Institute of Botany, Chinese Academy of Sciences
3. Present address: College of Plant Science, Jilin University
4. National Institute of Crop Science
5. Present address: Jomo Kenyatta University of Agriculture and Technology
6. Present address: Universidad Católica de Oriente
7. Research Faculty of Agriculture, Hokkaido University