1. Institute of Crop Sciences/National Wheat Improvement Center, Chinese Academy of Agricultural Sciences (CAAS), No 12 Zhongguancun South Street, Beijing 100081, PCR.
2. Corresponding author. E-mail: zhhe@public3.bta.net.cn
3. Crop Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, Shandong Province, PCR.
4. CIMMYT, Apdo-Postal 6-641, Mexico DF, Mexico.