Metabolic engineering of volatile isoprenoids in grapevine

Grapevine deoxyxylulose phosphate synthase (VvDXS) was reported as a positional candidate gene for muscat flavor having been co-localized with a major QTL for monoterpenoids in berries. Recently a putative causal SNP responsible for a non-neutral substitution in the VvDXS1 protein was found to be significantly associated with muscat flavored varieties and a functional effect of this polymorphism was proven in transgenic tobacco adopting a reverse genetics approach. Here we aimed at applying the same strategy in grapevine in order to deeply investigate the metabolic changes induced by the overexpression of the mutated or non-mutated form of VvDXS1. Embryogenic callus of a microvine genotype was used for Agrobacterium tumefaciens mediated gene transfer. The molecular characterization of transgenic plants showed that the line with a single T-DNA integration copy had the highest VvDXS1 expression. Besides, transgenic and WT in vitro plants were evaluated for the emission of volatile organic compounds through proton-transfer-reaction mass spectrometry.