493 Drawing Links from Transcriptome to Metabolites: the Evolution of Muscat Aroma in the Ripening Berry L. Costantini 1 , J. Battilana 1 , C. Kappel 2 , F. Emanuelli 1 , M. Sordo 1 , S. Delrot 2 and M.S. Grando 1 1 IASMA Research Centre, Fondazione Edmund Mach, San Michele all’Adige (TN), Italy 2 UMR EGFV, Institut des Sciences de la Vigne et du Vin, Villenave d’Ornon, France Keywords: ‘Moscato Bianco’, flavor, metabolic profile, monoterpenoids, microarray, data integration, candidate genes Abstract Owing to the role that aroma plays in the perceived quality of grapes and wines, there is a tremendous interest in understanding how the accumulation of sensory compounds is regulated at the molecular level. To this purpose, we applied an integrative functional genomics approach by simultaneously monitoring the abundance of transcripts and metabolites in ripening berries of ‘Moscato Bianco’ (Vitis vinifera L.). Gas chromatography-mass spectrometry analysis of thirty-two out of the most important ‘impact’ compounds (monoterpenoids, C 13 -norisoprenoids, benzenoids and C 6 -aliphatic compounds) in their free and bound forms was combined with a large-scale transcriptome analysis based on the use of the AROS 1.0 oligo- nucleotide microarray (14,562 probes) at five developmental stages from pre-véraison to over-ripe. Several exploratory methods were tested for the integration of transcript and metabolite profiles with the final goal of identifying genes or groups of genes that are linked with the accumulation of specific metabolites or groups of metabolites. Pair-wise metabolite-to-metabolite and gene-to-metabolite correlations were calcu- lated. Various types of clustering were performed by incorporating both differentially expressed genes and metabolites. Finally, modulated transcripts were checked for their potential co-localization with previously identified QTLs controlling the level of aromatic compounds. This work is expected to provide insight into the regulatory network of grapevine secondary metabolism and is aimed at identifying genes relevant to aroma determination both at the regulatory and catalytic levels. INTRODUCTION The floral flavor and aroma typical of Muscat cultivars is greatly appreciated for both fresh grape and wine consumption. The most important compounds that contribute this property are monoterpenoids deriving from the grapes (largely the skins), in particular linalool, geraniol, nerol, citronellol and α-terpineol. In addition to free volatile compounds, grapes contain glycosidically-bound compounds that are not directly responsible for aroma but they rather constitute a reserve of odorless precursors, which generate flavor upon hydrolysis (Mateo and Jiménez, 2000). Odorant-odorant interactions also occur and may affect the final perception The free and bound forms of the major monoterpenoids have been found to accumulate in ripening grapes, however conflicting results have been reported in some cases (Park et al., 1991 and references herein; Ebang-Oke et al., 2003). In general, our understanding of the biosynthesis of aroma compounds from grapes is limited. Some significant progress has been made in the last decade, which includes the demonstration of the dominant role of the plastidial MEP pathway in grape monoterpene biosynthesis (Luan and Wüst, 2002); the identification and characterization of some genes of the terpenoid pathway (Ebang-Oke et al., 2003; Lücker et al., 2004; Martin and Bohlmann, 2004; Mathieu et al., 2005); the in silico identification of terpene synthesis genes in the ‘Pinot Noir’ genome sequence (Jaillon et al., 2007; Velasco et al., 2007) and the clarification of Muscat aroma genetic architecture through QTL analysis (Doligez et al., 2006; Battilana et al., 2009). Nevertheless, genetic maps of biosynthetic pathways are still far from complete (partly due to the fact that a plethora of terpenoids Proc. X th Intl. Conf. on Grapevine Breeding and Genetics Eds.: B.I. Reisch and J. Londo Acta Hort. 1046, ISHS 2014