Hong Yu1,2, Jiayang Li3,4. 1. State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China. 2. University of Chinese Academy of Sciences, Beijing, China. 3. State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China. jyli@genetics.ac.cn. 4. University of Chinese Academy of Sciences, Beijing, China. jyli@genetics.ac.cn.