Hongyan Shan1, Hongzhi Kong2,3. 1. State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China. 2. State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China. hzkong@ibcas.ac.cn. 3. University of Chinese Academy of Sciences, Beijing, China. hzkong@ibcas.ac.cn.