CPSC Lecture with Søren Bak
On 20 April 2017 Professor Søren Bak from Section for Plant Biochemistry, Department of Plant and Environmental Sciences, University of Copenhagen will give a CPSC lecture on:
Triterpenoid saponins in a wild crucifer - biosynthesis, evolution and structure activity relationships in plant-insect interactions
It is well known that plants produce specialized metabolites for defense, yet we know little of how they actually evolved. Certain classes of chemical defense compounds have evolved repeatedly in plants, facilitated by recruitment of genes from a few old gene families.
This was probably mediated by gene duplications, either locally or by whole-genome duplications, followed by selection on their enzyme substrate and product specificity. The initial assumption that divergent evolution is the major player is being challenged, and it appears that convergent evolution is surprisingly common in specialised metabolite pathways (Pichersky and Lewinsohn 2011).
Triterpenoid saponins comprise a highly diverse group of specialised metabolites, derived from 2,3-oxidosqualene, the precursor for sterols in most eukaryotes. They are widespread in different plants families suggesting that their biosynthesis has evolved convergently.
We have developed the wild crucifer Barbarea vulgaris as a model system to study the biosynthesis of triterpenoid saponins, the genome localization of the genes involved in the pathway, and reconstituted the pathway in tobacco leaves. Structure-activity relationships studies using insects, such as the crucifer pest Diamond back moth, begin to unravel which chemical features of saponins influence toxicity to specific insects.
About Søren Bak
Søren Bak is Head of Section for Plant Biochemistry at Department of Plant and Environmental Sciences, University of Copenhagen and research group leader of the High Value Compound group.
He took his PhD from the Royal Veterinary and Agricultural University (KVL) in 1997 and after that went to The University of Arizona, USA. He returned to KVL in 2000 to the Department of Biology. His current research at Department of Plant and Environmental Sciences focuses on high-value terpenoids with pharmacological or biological activity, yet with limited natural sources.
Søren Bak's research group "High value compounds".