The metabolic engineering of VvDXS1 gene in grapevine for a functional evaluation of terpenoids metabolism during physiological fruit development or under stress conditions

Terpenoids, the largest family of natural compounds in plants, derive from the plastidial MEP- or from the cytosolic MVA-pathway and are involved in important biological functions. Volatile and non-volatile terpenoids are implicated in the attraction of both pollinators and predators of herbivores, in protecting against photo-oxidative stress, in mediating thermo-tolerance and in plant defence against pathogens. They have also a huge commercial value in primis for their use as flavors and fragrances. In grapevine, monoterpenes are the main responsible of Muscat aroma, one of the most appreciated quality trait in wine and table grape. In this study a functional analysis of VvDXS1 , the first and probably the rate-limiting enzyme of the MEP pathway route, has been carried out in grapevine. In particular, two allelic forms of VvDXS1 which differed for a non-synonymous single nucleotide polymorphism (a ‘neutral’ allele and a ‘Muscat-type allele’) have been overexpressed in ‘microvine’, a grapevine model system. The expression pattern of many genes involved in terpenoids biosynthesis was assessed at various stages of berry development in transgenic and WT plants. Moreover, an evaluation of the transgenic plants under abiotic stress is in progress to disclose possible advantages in plant stress response resulting from an increased MEP pathway flux.