Muscat Flavor in Grapevine: A Digital PCR Assay to Track Allelic Variation in VvDXS Gene

Abstract

The aroma of grapes and derived wines has long been one of the major traits considered in the selection of grapevine varieties through the centuries. In particular, Muscat aromatic grapes have been highly appreciated and widespread since ancient times. Monoterpenes are the key compounds responsible for the Muscat flavor. A major QTL affecting monoterpene level has been found to co-localize with the 1-deoxy-D-xylulose 5-phosphate synthase (VvDXS) gene, encoding for the 1-deoxy-D-xylulose 5-phosphate synthase enzyme involved in the plastidial pathway of terpene biosynthesis. In more detail, a single nucleotide polymorphism (SNP 1822) in the coding region of the gene causes a “gain of function” mutation, which is involved in Muscat flavor. In this work, we have developed a digital PCR-based assay to target allelic variations in the VvDXS gene, SNP1822, with the aim to propose a fast and sensitive analytical tool for targeting Muscat-flavored grapevine genotypes. The assay accurately predicts the genetic structure at 1822 SNP, critical for the development of the aroma in the great majority of Muscats. In the case of grapes in which the aromatic component is due to mutations other than SNP 1822 (e.g., Chasselas Musqué and Chardonnay Muscat), further specific assays can be developed.

Effects of Girdling and Foliar Fertilization with K on Physicochemical Parameters, Phenolic and Volatile Composition in ‘Hanxiangmi’ Table Grape

“…Additionally, we found that only VvDXS was significantly correlated with linalool and total terpene concentrations, while the expression of other terpene-related genes were apparently uncorrelated with terpene accumulation in general (Figure 5). DXS is the first enzyme involved in the MEP pathway of isopentenyl-5-pyrophosphate (IPP) biosynthesis [59]. Our observation of the correlation between grape linalool content and VvDXS expression is in agreement with Battilana et al [57] and Emanuelli et al [60] (Table 5), who demonstrated the colocalization of VvDXS with the major QTL for monoterpene content positioned on chromosome 5, and indicating that VvDXS is a candidate gene for the regulation of these important grape monoterpenes.…”

Transcriptomic and free monoterpene analyses of aroma reveal that isopentenyl diphosphate isomerase inhibits monoterpene biosynthesis in grape (Vitis vinifera L.)

“…Previous studies have reported that terpene accumulation in grape and other plants was correlated with gene expression in the MEP pathway [17], such as VvDXS, VvDXR, VvHDR and VvGPPS [18][19][20]. Of the corresponding proteins, DXS is the first enzyme involved in the MEP pathway [21]. Battilana et al [18] and Emanuelli et al [22] reported the co-localization of VvDXS with a major quantitative trait locus (QTL) for monoterpene concentration positioned on chromosome 5 of grapevine.…”

A Molecular Toolbox to Identify and Quantify Grape Varieties: On the Trace of “Glera”

“…Few studies have applied this technology to other objectives, such as the evaluation of gene expression or the control of edited plants. Moving toward traceability applications, Morcia et al [ 48 ] developed a digital PCR for the identification and quantification of Muscat-flavored grapes, but no example of digital PCR applied to the traceability of a specific grape variety has been proposed until now. Several DNA-based technologies are currently used for varietal genotyping [ 8 ], among them even one able to give in-the-field varietal authentication [ 49 ].…”