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Research Interests
The topics in my group concern the biosynthesis, regulation and biological role of volatiles. In the last decade Petunia hybrida has emerged as the model of choice to study volatile benzenoid and phenylpropanoid synthesis, emission and regulation. These volatiles are synthesized predominantly in the corolla limb and emission is highly regulated, with a circadian rhythm, during corolla development, pollination and senescence. With all the biochemical and molecular tools available much of our understanding of volatile benzenoid/phenylpropanoid has been obtained with Petunia. The knowledge obtained with this system is being applied to alter tomato fruit volatile production and thereby taste. In addition, we use tomato as a model system to study the role of terpenoids in its interaction with insects. We focus on terpene synthases expressed in trichomes and have identified severalterpenoids that repel or attract whiteflies. Ouraim is to engineer the production of these terpenoids for which we have identified trichome specific promoters. Finally, we use Arabidopsis for forward genetic screens to identify genes important in the response to the wound-induced C6-volatile E-2-hexenal. We also aim to identify genes that are specifically regulated by E-2-hexenal using a transcriptomics approach.
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 Floral scent production by Petunia
We have discovered, through a targeted metabolomics and transcriptomics approach, ODORANT1, the first transcription factor that regulates benzenoid synthesis and provided insight in how Petunia flowers developmentally separate color and scent biosynthesis; we have recently discovered a 3-ketoacylthiolase that catalyzes an important step in benzoic acid biosynthesis
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 The role of volatile terpenoids in tomato-insect interactions.
We have established a role for jasmonate (JA) in the production of volatile terpenoids in tomato upon herbivoryand discovered that JA induces the expression of salicylic acid (SA) methyl transferase that converts SA to the volatile methyl salicylate. We have also identified and characterized the first monoterpene synthases from tomato that are specifically expressed and induced by JA in trichomes. Moreover, we have discovered that geranyldiphosphate synthase is essential in tomato and Arabidopsis for the synthesis of gibberellins and that JA and SA are both necessary for the synthesis of the C16-homoterpene TMTT. Recently we identified the tomato terpenoidsthat are directly involved in repellingorattracting whiteflies. Through 454 and GS-flex sequencing of trichome cDNAs of wild tomatoes we identified the corresponding terpenoid synthases. We are currently modifyingcultivated tomato plants to produce the relevant terpenoids using trichome specific promoters.
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Green leaf volatiles
We also investigate the role of C6 volatiles as signaling and priming molecules. These C6 volatiles are produced in most, if not all, plants upon wounding and insect herbivory and can prime the defense of neighboring plants. We have identified the first Arabidopsis mutants that are resistant to E-2-hexenal (her mutants) and have mapped the her1 mutation to chromosome 3 to discover a role for GABA in this process. We are currently close to mapping and cloning other her mutants. We also discovered that GABA plays an important role in the defense against Pseudomonas
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Teaching interests
I coordinate the first year course 'Plant Biology' and the third year course 'Signal transduction and communication'. I also give lectures in various other courses.
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