1. Department of Botany, University of British Columbia, Vancouver BC V6T 1Z4, Canada
2. Department of Plant Biochemistry, Georg-August-University, Albrecht-von-Haller-Institute for Plant Sciences, D-37073 Goettingen, Germany
3. Department of Chemistry, University of British Columbia, Vancouver BC V6T 1Z4, Canada
4. National Institute of Biological Sciences, Beijing 102206, China
5. Department of Plant Biochemistry, Georg-August-University, Goettingen Center for Molecular Biosciences, D-37073 Goettingen, Germany