1. Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing 100081, P. R. China
2. The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing 100081, P. R. China
3. Zhongyuan Research Center, Chinese Academy of Agricultural Sciences, Xinxiang 453000, P. R. China