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BACKGROUND:Monoterpenes and C13-norisoprenoids are key terpenoid compounds for wine aroma. The enzyme encoded by VviDXS1 participates in terpenoid biosynthesis in grapevine fruits and gain-of-function mutations in this gene lead to characteristic muscat aroma. OBJECTIVE:To assess for VviDXS1 contribution to aroma variation in Northwestern Iberian wine cultivars, we resequenced this gene in 111 cultivars and compared grape juice terpenic composition in 12 of them. METHODS:VviDXS1 was capture-targeted for resequencing with Illumina paired-end reads, SAMtools was used for variant calling and gene haplotypes were reconstructed with PHASE. Monoterpenes and C13-norisoprenoids were quantified in free and glycosidically-bound forms from grape juice by gas chromatography-mass spectrometry. RESULTS:Terpenic composition discriminated between muscat, terpenic and neutral profiles across cultivars. While the terpenic profile of Loureira and Albariño white cultivars was not associated with muscat-like mutations, Albariño carries a V34L substitution in VviDXS1 that is also present in other aromatic cultivars and was not reported before. Tempranillo and Cabernet Sauvignon red cultivars accumulated higher levels of C13-norisoprenoids, which was not associated with specific variation in VviDXS1. CONCLUSIONS:Apart from the uncharacterized substitution present in Albariño, findings suggest that terpenoid pathway-related genes other than VviDXS1 could contribute to the aromatic attributes of these cultivars.
