Current Reseach (PhD Thesis):
Identification and characterization of glandular enzymes involved in defensive compound biosynthesis of leaf beetle larvae
As the complete life of chrysomeline leaf beetles takes place on the same plant, a whole string of characters like reproduction, development and feeding are influenced by their host. Relating to their larval glandular chemical defense against predators and microbial attack, different adaptations to their host-plant chemistry exist. While many leaf beetles synthesize their defensive compounds de novo by their own, a number of species partly or completely depends on ingested secondary compounds from their host-plant.
I basically focus on salicin sequestering Chrysomela species originally feeding on salicaceous plants. Inside their larval defensive glandular reservoirs salicin is converted by the consecutive action of a Glucosidase and a Oxidase to the bioactive principle salicylaldehyde. Interestingly, within the genus Chrysomela some species are able to produce esters of larva and host-plant origin as defensive compounds. This is seen as a derived state of chemical defense that softens the absolute adaptation to salicin containing host-plants and most likely facilitates host-plant shifts.
We are interested in the identification of enzymes involved in salicylaldehyde biosynthesis, their evolutionary origin and their fate after shifts to non-salicaceous host-plants.
To address those research interests, we use proteomic tools in combination with in-house created cDNA and genomic libraries. Candidate genes are heterologously expressed in incect cell lines and tested for their catalytic activities. Genes tested as positives are used to obtain their homologs in different chrysomeline species, followed by phylogenetic analyses.
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