1. Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China (W.Q., J.Z., Q.Wu., Q.Wa., X.L., D.Y., Y.J., Ga.W., Gu.W., R.S.); and Coordinated Crop Biology Research Center, Beijing 100193, China (W.Q., Ga.W., Gu.W., R.S.) and National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China (R.S)