Sha Li1, Yan Zhang2. 1. State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Daizong St. 61, Tai'an, Shandong, China. 2. State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Daizong St. 61, Tai'an, Shandong, China. Electronic address: yzhang@sdau.edu.cn.