title: Metabolite and transcript profiling of berry skin during fruit development elucidates differential regulation between Cabernet Sauvignon and Shiraz cultivars at branching points in the polyphenol pathway.
abstract: BACKGROUND
  Grapevine berries undergo complex biochemical changes during fruit maturation, many of which are dependent upon the variety and its environment. In order to elucidate the varietal dependent developmental regulation of primary and specialized metabolism, berry skins of Cabernet Sauvignon and Shiraz were subjected to gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) based metabolite profiling from pre-veraison to harvest. The generated dataset was augmented with transcript profiling using RNAseq.
  
  
  RESULTS
  The analysis of the metabolite data revealed similar developmental patterns of change in primary metabolites between the two cultivars. Nevertheless, towards maturity the extent of change in the major organic acid and sugars (i.e. sucrose, trehalose, malate) and precursors of aromatic and phenolic compounds such as quinate and shikimate was greater in Shiraz compared to Cabernet Sauvignon. In contrast, distinct directional projections on the PCA plot of the two cultivars samples towards maturation when using the specialized metabolite profiles were apparent, suggesting a cultivar-dependent regulation of the specialized metabolism. Generally, Shiraz displayed greater upregulation of the entire polyphenol pathway and specifically higher accumulation of piceid and coumaroyl anthocyanin forms than Cabernet Sauvignon from veraison onwards. Transcript profiling revealed coordinated increased transcript abundance for genes encoding enzymes of committing steps in the phenylpropanoid pathway. The anthocyanin metabolite profile showed F3'5'H-mediated delphinidin-type anthocyanin enrichment in both varieties towards maturation, consistent with the transcript data, indicating that the F3'5'H-governed branching step dominates the anthocyanin profile at late berry development. Correlation analysis confirmed the tightly coordinated metabolic changes during development, and suggested a source-sink relation between the central and specialized metabolism, stronger in Shiraz than Cabernet Sauvignon. RNAseq analysis also revealed that the two cultivars exhibited distinct pattern of changes in genes related to abscisic acid (ABA) biosynthesis enzymes.
  
  
  CONCLUSIONS
  Compared with CS, Shiraz showed higher number of significant correlations between metabolites, which together with the relatively higher expression of flavonoid genes supports the evidence of increased accumulation of coumaroyl anthocyanins in that cultivar. Enhanced stress related metabolism, e.g. trehalose, stilbene and ABA in Shiraz berry-skin are consistent with its relatively higher susceptibility to environmental cues.
authors: Asfaw
authors: A
authors: Degu
authors: Uri
authors: U
authors: Hochberg
authors: Noga
authors: N
authors: Sikron
authors: Luca
authors: L
authors: Venturini
authors: Genny
authors: G
authors: Buson
authors: Ryan
authors: R
authors: Ghan
authors: Inbar
authors: I
authors: Plaschkes
authors: Albert
authors: A
authors: Batushansky
authors: Vered
authors: V
authors: Chalifa-Caspi
authors: Fulvio
authors: F
authors: Mattivi
authors: Massimo
authors: M
authors: Delledonne
authors: Mario
authors: M
authors: Pezzotti
authors: Shimon
authors: S
authors: Rachmilevitch
authors: Grant R
authors: GR
authors: Cramer
authors: The French Associates Institute for Agriculture and Biotechnology of Drylands, the Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer 84990, Israel. fait@bgu.ac.il.
authors: Aaron
authors: A
authors: Fait
mesh_terms: D000872:Anthocyanins / Q000737:chemistry; D002853:Chromatography, Liquid; D005419:Flavonoids / Q000737:chemistry; D005638:Fruit / Q000235:genetics / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D055442:Metabolome; D059808:Polyphenols / Q000737:chemistry; D059467:Transcriptome; D027843:Vitis / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D014920:Wine
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D059808:Polyphenols