1. State Key Laboratory for Agrobiotechnology and Key Laboratory of Crop Heterosis and Utilization (MOE) and Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, P.R. China
2. State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Horticulture, South China Agricultural University, Guangzhou 510642, P.R. China
3. Council for Agricultural Research and Economics, Research Centre for Cereal and Industrial Crops, I-24126 Bergamo, Italy