1 The Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan Road, Beijing 100093, China.
2 Natural Product Center, School of Natural Resources and the Environment, The University of Arizona, 250 East Valencia Road, Tucson, AZ 85706, USA.
3 The Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan Road, Beijing 100093, China. Electronic address: xqi@ibcas.ac.cn.