Identification and regulation of the stilbene biosynthetic pathway genes from grapevine

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Plant stilbenes are phytoalexins that accumulate in a number of plant species in response to biotic and abiotic stresses. In recent years, stilbenes have received widespread attention in medical research because of its implication in many beneficial effects on human health. Stilbenes have been detected in at least 72 plant species including crops like peanut, blueberry and grapevine. Plants accumulate stilbenes in significant amounts not only in vegetative parts, but also in fruits, which are used as food or in the production of juices and wines. In contrast to the large diversity of described stilbenes with different biological activities, only two enzymes of the stilbene pathway have been identified and characterized up to now. Considering the various modifications of the basic stilbene skeleton and the transport of stilbenes additional unknown genes and gene products have to be present for these processes. Also the regulation of the stilbene pathway on the molecular level was unknown untill the recent identification and characterization of the two grapevine transcription factors VvMYB14 and VvMYB15 specifically regulating the stilbene pathway (Höll et al., 2013). Overexpression of these transcription factors and subsequent microarray, RNAseq and chromatin immunoprecipitation (ChiP) analysis will be used in the applied research project to initially identify the target genes of the transcription factors. Thereby, yet unknown genes of the stilbene pathway can be analysed and their regulation be studied in detail. Ectopic expression of these structural genes will allow the biochemical characterization of the respective gene products. Additionally, genetic differences of grapevine cultivars or species and influences of environmental factors on the stilbene pathway related to the optimization of grapevine stilbene content will be studied. Therefore, this research project will provide new insights into the molecular basis and the regulation of the stilbene pathway in plants, which is still poorly understood. The basic results concerning the genetic differences of grapevine cultivars or species and the impact of environmental factors on stilbene metabolism could allow optimisation of grapevine stilbene content via subsequent grapevine breeding approaches or adaptation of viticultural practices.