Investigation of VvDXS function and its effects on muscat flavor levels

In the present study the connection between the positional candidate gene VvDXS and muscat flavor was evaluated by investigating the expression profiles in the berries from a Muscat-type cultivar and a neutral cultivar and its nucleotide diversity of full ORF on grapevine accessions. The relationship between the transcription profile of VvDXS alleles and monoterpenoid content suggests that a particular trend in gene expression rather than the level of expression ratio affects monoterpenoid accumulation in ‘Moscato Bianco’. However a putative causal SNP responsible for a predicted non-neutral substitution was found to be significantly associated with muscat-flavored cultivars. Functional assays suggest that the putative causal SNP raises monoterpenoid accumulation by changing the 3D protein structure and by increasing VvDXS activity in Muscat enzyme form.