Saponin structure-activity relationships: biological activity, ecological function and evolution – University of Copenhagen

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Plant and Environmental Sciences > Research > Plant Biochemistry > High value compounds > Project: Saponin struc...

Saponin structure-activity relationships: biological activity, ecological function and evolution

Wild plants have evolved an astounding diversity of chemical defenses against their enemies in a chemical arms race between defense systems in plants and counter-adaptations in the enemies. However, this resource is largely unexplored by modern agriculture, despite its obvious potential for pest control in the form of bio-pesticides and for breeding resistance genes into crop plants.

In order to utilize plant defenses in an optimal way, we need to understand the relationship between chemical structure of plant defense compounds and their biological activity, ecological function and evolution. Furthermore, we need to know the biosynthesis of efficient defence compounds.

Saponins constitute a structurally highly diverse class of natural plant defense compounds. Due to their detergent-like structures, they can disrupt cell membranes, cause cell death, and ultimate kill herbivores and pests. Despite their obvious potential for use in plant protection, we know surprisingly little about which saponin structures are toxic to certain herbivores, and which are not.

Structure Activity Relationships – what determines bioactivity?

Fat Diamond back moth (Plutella xylostella) larvae on plant without saponin.

The aim of this project is to understand the relationship between saponin chemical structures and their biological activity, ecological function and evolution. We will explore natural variation in saponin structures in a group of wild crucifer species, with special focus on interspecific hybrids, and identify and analyze the underlying enzyme-encoding genes. In addition, we will metabolically engineer novel saponins in model plants by expressing combinations of these biosynthetic genes. The effect of this palette of saponin structures will be tested in bioassays and ecological experiments with specialist and generalist insect pests, as well as in insect cell lines.

Collaboration

In the project, we are collaborating with

Funding

The project is supported by a grant from the Danish Research Council (Bevillings-ID: DFF – 1335-00151)

Selected publications

  • van Mölken T, Heimes C, Hauser TP, Sundelin T (2014) Phylogeny of an Albugo sp. infecting Barbarea vulgaris in Denmark and its frequency of symptom development in natural populations of two evolutionary divergent plant types. Fungal Biology 118, 340-347.
  • Augustin JM, Drok S, Shinoda T, Sanmiya K, Nielsen JK, Khakimov B, Olsen CE, Hansen EH, Kuzina V, Ekstrøm CT, Hauser T, Bak S (2012). UDP-glycosyltransferases from the UGT73C Subfamily in Barbarea vulgaris catalyse Sapogenin 3-O-glucosylation in Saponin-mediated Insect resistance. Plant Physiology 160, 1881-1895.
  • Toneatto F, Hauser TP, Nielsen JK, Ørgaard M (2012) Genetic diversity and similarity in the barbarea vulgaris complex (brassicaceae). Nordic Journal of Botany 30, 506-512.
  • Hauser TP, Toneatto F, Nielsen JK (2012) Genetic and geographic structure of an insect resistant and a susceptible type of Barbarea vulgaris in western Europe. Evolutionary Ecology, 26, 611-624.
  • Dalby-Brown L, Olsen CE, Nielsen JK, Agerbirk N (2011). Polymorphism for Novel Tetraglycosylated Flavonols in an Eco-model Crucifer, Barbarea vulgaris. Journal of Agricultural and Food Chemistry 59, 6947–6956.
  • Augustin JM, Kuzina V, Andersen SB & Bak S (2011) Molecular activities, biosynthesis and evolution of triterpenoid saponins. Phytochemistry 72, 435-457.
  • Kuzina V, Nielsen JK, Augustin JM, Torp AM, Bak B, Andersen SB (2011) Barbarea vulgaris linkage map and quantitative trait loci for saponins, glucosinolates, hairiness and resistance to the herbivore Phyllotreta nemorum. Phytochemistry 72, 188-198.
  • Toneatto F, Nielsen JK, Ørgaard M, Hauser TP (2010) Genetic and sexual separation between insect resistant and susceptible Barbarea vulgaris plants in Denmark. Molecular Ecology 19, 3456-3465.
  • Nielsen J, Nagao T, Okabe H, Shinoda T (2010) Resistance in the Plant, Barbarea vulgaris, and Counter-Adaptations in Flea Beetles Mediated by Saponins. Journal of Chemical Ecology 36, 277-285.
  • de Jong PW et al. (2009) Genetic differentiation between resistance phenotypes in the phytophagous flea beetle, Phyllotreta nemorum. pp.pp8. Journal of Insect Science 9: 75-
  • Kuzina V, Ekstrom CT, Andersen SB, et al. (2009) Identification of Defense Compounds in Barbarea vulgaris against the Herbivore Phyllotreta nemorum by an Ecometabolomic Approach. Plant Physiology 151, 1977-1990.