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Elucidating and quantifying the detoxification of plant defensive compounds in insects.

Glucosinolates are secondary metabolites in plants from the Brassicaceae family used as activated chemical defenses against herbivory. During plant development glucosinolates are synthesized from certain amino acids leading to products with different side chains. Upon attack, these glycosides can be enzymatically hydrolyzed by plant myrosinases to form chemically unstable aglucones, that are spontaneously converted to isothiocyanates, thiocyanates, nitriles and etc., which can be toxic to insects. Nevertheless, some insect species are able to detoxify glucosinolates and their derived products and use these plants as a food source. Interestingly, some insects possess mechanisms not only to avoid the toxicity of glucosinolates, but also to use these metabolites for their own benefit.

The aim of this project is to investigate biochemical mechanisms such as detoxification and sequestration that help selected herbivores to avoid the toxicity of different glucosinolates. Using radioactive and stable isotope labeling of glucosinolates in planta and further feeding of radioactive leaves to insects, we will be able to both elucidate and quantify products of detoxification and transport through the body. Additionally, chemical and biological activities can vary between alkyl, benzylic and indolic glucosinolates and their products. Thus, we intend to reveal the effect of glucosinolate side-chain groups on detoxification routes, by comparing metabolite profiles from feeding experiments using radioactive glucosinolates with different detoxification products. Furthermore, we are going to study the enzymes and corresponding genes involved in the process of detoxification in order to gain more insight into the role of these metabolic pathways in the herbivore/plant interaction. This will help shed light on the ecological role of producing mixture of glucosinolates as observed in most crucifers. Having several defensive compounds could mean that each of them should behave differently during digestion, targeting separate pathways, being differentially detoxified, or even working in synergy with each other.
last updated on 2016-10-10