The genes and enzymes of the carotenoid metabolic pathway in Vitis vinifera L.

Abstract

BackgroundCarotenoids are a heterogeneous group of plant isoprenoids primarily involved in photosynthesis. In plants the cleavage of carotenoids leads to the formation of the phytohormones abscisic acid and strigolactone, and C13-norisoprenoids involved in the characteristic flavour and aroma compounds in flowers and fruits and are of specific importance in the varietal character of grapes and wine. This work extends the previous reports of carotenoid gene expression and photosynthetic pigment analysis by providing an up-to-date pathway analysis and an important framework for the analysis of carotenoid metabolic pathways in grapevine.ResultsComparative genomics was used to identify 42 genes putatively involved in carotenoid biosynthesis/catabolism in grapevine. The genes are distributed on 16 of the 19 chromosomes and have been localised to the physical map of the heterozygous ENTAV115 grapevine sequence. Nine of the genes occur as single copies whereas the rest of the carotenoid metabolic genes have more than one paralogue. The cDNA copies of eleven corresponding genes from Vitis vinifera L. cv. Pinotage were characterised, and four where shown to be functional. Microarrays provided expression profiles of 39 accessions in the metabolic pathway during three berry developmental stages in Sauvignon blanc, whereas an optimised HPLC analysis provided the concentrations of individual carotenoids. This provides evidence of the functioning of the lutein epoxide cycle and the respective genes in grapevine. Similarly, orthologues of genes leading to the formation of strigolactone involved in shoot branching inhibition were identified: CCD7, CCD8 and MAX1. Moreover, the isoforms typically have different expression patterns, confirming the complex regulation of the pathway. Of particular interest is the expression pattern of the three VvNCEDs: Our results support previous findings that VvNCED3 is likely the isoform linked to ABA content in berries.ConclusionsThe carotenoid metabolic pathway is well characterised, and the genes and enzymes have been studied in a number of plants. The study of the 42 carotenoid pathway genes of grapevine showed that they share a high degree of similarity with other eudicots. Expression and pigment profiling of developing berries provided insights into the most complete grapevine carotenoid pathway representation. This study represents an important reference study for further characterisation of carotenoid biosynthesis and catabolism in grapevine.

Origins of Grape and Wine Aroma. Part 1. Chemical Components and Viticultural Impacts

“…In grapes, water deficits increased levels of carotenoids and selected C 13 -norisoprenoids produced from carotenoid degradation in some studies (Bindon et al 2007, Grimplet et al 2007, although the effect may depend on the norisoprenoid measured (Ou et al 2010). These results are consistent with a recent study that indicates that regulation of carotenoid metabolism/degradation is highly complex and may occur at multiple levels (Young et al 2012). Water deficits have had variable effects on monoterpene levels, with either no effect or elevating the concentrations of some compounds (Grimplet et al 2007, Ou et al 2010.…”

“…These carotenoid cleavage dioxygenase (CCD) enzymes cleave the C 40 carotenoids mainly at the 9,10 and 9'10' double bonds. Four subfamilies have been identified-CCD1, CCD4, CCD7, and CCD8-and cleavage may be symmetric or asymmetric depending on the enzyme and carotenoid substrate (Auldridge et al 2006, Walter et al 2010, Young et al 2012). Recently, studies in Crocus sativa, rice, and mycorrhizal roots of Medicago truncatula indicate that CCD4 and CCD7 may be localized in the plastid and the C 13 -and C 27 -apocarotenoids obtained from carotenoid cleavage are exported to the cytosol where further cleavage by CCD1 occurs, yielding C 13 -and C 14 -apocarotenoid products (Floss et al 2008, Rubio et al 2008, Ilg et al 2010).…”

“…CCD7 and CCD8 are thought to be involved in formation of strigolactone, a plant hormone that inhibits shoot branching (Ruyter-Spira et al 2013). The reported increase in expression of a CCD4 gene after veraison is suggestive of a role for this enzyme late in berry ripening (Guillaumie et al 2011, Young et al 2012.…”

Integrated Network Analysis Identifies Fight-Club Nodes as a Class of Hubs Encompassing Key Putative Switch Genes That Induce Major Transcriptome Reprogramming during Grapevine Development

“…The secondary metabolic processes represented by switch genes include phenylpropanoid biosynthesis (two flavonol synthases) and modification (three caffeic acid O-3-methyltransferases), reflecting the developmental shift toward the production of aromatic compounds. Another metabolic switch gene encoded (9,10) (9ʹ,10ʹ) carotenoid cleavage dioxygenase (CCD4b), whose expression increases dramatically during berry development, proportional to the loss of carotenoids (Young et al, 2012). CCD4b may protect plants against oxidative stress during fruit maturation by promoting the biosynthesis of abscisic acid (Cakir et al, 2003).…”

“…Another 12 switch genes encoded transporters, including the anthoMATE transporter AM2, which was recently shown to regulate the malvidin content of Malbec berries (Muñoz et al, 2014). Further switch genes were found to encode enzymes catalyzing early steps in the phenylpropanoid pathway, e.g., caffeic acid 3-O-methyltransferase and 4-coumarate-CoA ligase, or components of terpenoid and carotenoid metabolism, e.g., CCD4b encoding a carotenoid cleavage dioxygenase that generates typical grape berry aromatic compounds (Young et al, 2012). All three enzymes were also represented by switch genes in the atlas data set.…”