Authors: Cecilie Cetti Hansen, Mette Sørensen, Matteo Bellucci, Wolfgang Brandt, Carl Erik Olsen, Jason Q. D. Goodger, Ian E. Woodrow, Birger Lindberg Møller, Elizabeth H. J. Neilson
- Plant Biochemistry Laboratory, Department of Plant and Environmental Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
- Novo Nordisk Foundation Center for Protein Research, Protein Production and Characterization Platform, University of Copenhagen, 2200 Copenhagen, Denmark
- Department of Bioorganic Chemistry, Leibniz-Institute of Plant Biochemistry, Halle, 06120 Germany
- School of BioSciences, The University of Melbourne, Parkville, Vic., 3052 Australia
Publication: New Phytologist Journal
Date: October 2022
The economic and ecologically important genus Eucalyptus is rich in structurally diverse specialized metabolites. While some specialized metabolite classes are highly prevalent across the genus, the cyanogenic glucoside prunasin is only produced by c. 3% of species.
To investigate the evolutionary mechanisms behind prunasin biosynthesis in Eucalyptus, we compared de novo assembled transcriptomes, together with online resources between cyanogenic and acyanogenic species. Identified genes were characterized in vivo and in vitro.
Pathway characterization of cyanogenic Eucalyptus camphora and Eucalyptus yarraensis showed for the first time that the final glucosylation step from mandelonitrile to prunasin is catalyzed by a novel UDP-glucosyltransferase UGT87. This step is typically catalyzed by a member of the UGT85 family, including in Eucalyptus cladocalyx. The upstream conversion of phenylalanine to mandelonitrile is catalyzed by three cytochrome P450 (CYP) enzymes from the CYP79, CYP706, and CYP71 families, as previously shown. Analysis of acyanogenic Eucalyptus species revealed the loss of different ortholog prunasin biosynthetic genes.
The recruitment of UGTs from different families for prunasin biosynthesis in Eucalyptus demonstrates important pathway heterogeneities and unprecedented dynamic pathway evolution of chemical defense within a single genus. Overall, this study provides relevant insights into the tremendous adaptability of these long-lived trees.