1. State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, 100193, China
2. Key Laboratory of Crop Heterosis and Utilization (Ministry of Education), China Agricultural University, Beijing, 100193, China
3. Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193, China
4. Council for Agricultural Research and Economics, Research Centre for Cereal and Industrial Crops, I-24126 Bergamo, Italy