Unknown,Transcriptomics,Genomics,Proteomics

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A grapevine anthocyanin acyltransferase, transcriptionally regulated by VvMYBA, can produce most acylated anthocyanins present in grape skins

ABSTRACT: Anthocyanins are flavonoid compounds responsible for red/purple colours in the leaves, fruit and flowers of many plant species. They are produced through a multistep pathway which is controlled by MYB transcription factors. VvMYBA1 and VvMYBA2 activate anthocyanin biosynthesis in grapevine (Vitis vinifera) and are non-functional in white grapevine cultivars. In this study, transgenic grapevines with altered VvMYBA gene expression were developed, and transcript analysis was carried out on berries using a microarray technique. The results showed that VvMYBA is a positive regulator of the later stages of anthocyanin synthesis, modification and transport in Shiraz. One up-regulated gene ANTHOCYANIN 3- O-GLUCOSIDE-6â-O-ACYLTRANSFERASE (Vv3AT) encodes a BAHD acyltransferase protein, belonging to a clade separate from most anthocyanin acyltransferases. Functional studies (in planta and in vitro) show that Vv3AT has a broad anthocyanin substrate specificity and can also utilise both aliphatic and aromatic acyl donors, a novel activity for this enzyme family found in nature. In V. vinifera cv. Pinot Noir, a red-berried grapevine mutant lacking acylated anthocyanins, Vv3AT contains a nonsense mutation encoding a truncated protein that lacks two motifs required for BAHD protein activity. Promoter activation assays confirm that Vv3AT transcription is activated by VvMYBA1, which adds to the current understanding of the regulation of the BAHD gene family. The flexibility of Vv3AT to use both classes of acyl donors will be useful in the engineering of anthocyanins in planta or in vitro. Transgenic Chardonnay/Shiraz and non-transformed WT controls were all grown in the same glasshouse in ambient light with a night break. Day and night temperatures were approximately 27oC and 22oC respectively. For microarray experiments, whole berries were sampled from independent transgenic lines: three from transgenic Chardonnay and four from transgenic Shiraz, resulting in three and four biological replicates respectively. Bunches were harvested close to ripeness based on average total soluble solids (TSS, measured as oBrix). This was aimed to be between 20 â 24 oBrix and was determined from TTS of a subsamples from each bunch (Table S53). A sample consisted of all remaining berries from a single bunch except when there were <100 berries in which case more than one bunch was used in the one replicate. Whole berries were immediately frozen in liquid nitrogen. For skin samples, the skins were first removed from fresh berries then frozen in liquid nitrogen. All samples were stored at -80oC.

ORGANISM(S): Vitis vinifera

SUBMITTER: Marianna Fasoli

PROVIDER: E-GEOD-56915 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

A Grapevine Anthocyanin Acyltransferase, Transcriptionally Regulated by VvMYBA, Can Produce Most Acylated Anthocyanins Present in Grape Skins.

Rinaldo Amy R AR Cavallini Erika E Jia Yong Y Moss Sarah M A SM McDavid Debra A J DA Hooper Lauren C LC Robinson Simon P SP Tornielli Giovanni B GB Zenoni Sara S Ford Christopher M CM Boss Paul K PK Walker Amanda R AR

Plant physiology 20150922 3

Anthocyanins are flavonoid compounds responsible for red/purple colors in the leaves, fruit, and flowers of many plant species. They are produced through a multistep pathway that is controlled by MYB transcription factors. VvMYBA1 and VvMYBA2 activate anthocyanin biosynthesis in grapevine (Vitis vinifera) and are nonfunctional in white grapevine cultivars. In this study, transgenic grapevines with altered VvMYBA gene expression were developed, and transcript analysis was carried out on berries u ...[more]

PMID: 26395841

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Project description:Background: The composition of grapevine berry at harvest is a major determinant of wine quality. Optimal oenological maturity of berries is characterized by a high sugar/acidity ratio, high anthocyanin content in the skin, and low astringency. However, harvest time is still mostly determined empirically, based on crude biochemical composition and berry tasting. In this context, it is interesting to identify genes that are expressed/repressed specifically at the late stages of ripening and which may be used as indicators of maturity. Results: Whole bunches and berries sorted by density were collected in vineyard on Chardonnay (white cultivar) grapevines for two consecutive years at three stages of ripening (7-days before harvest (TH-7),harvest (TH), and 10-days after harvest (TH+10)). Microvinification and sensory analysis indicate that the quality of the wines made from the whole bunches collected at TH-7, TH and TH+10 differed, TH providing the highest quality wines. In parallel, gene expression was studied with Qiagen/Operon microarrays using two types of samples, i.e. whole bunches and berries sorted by density. Only 12 genes were consistently up- or down-regulated in whole bunches and density sorted berries for the two years studied in Chardonnay. 52 genes were differentially expressed between the TH-7 and TH samples. In order to determine whether these genes followed a similar pattern of expression during the late stagesof berry ripening in a red cultivar, nine genes were selected for RT-PCR analysis with Cabernet Sauvignon grown under two different temperature regimes affecting the precocity of ripening. The expression profiles and their relationship to ripening were confirmed in Cabernet Sauvignon for seven genes, encoding a carotenoid cleavage dioxygenase, a galactinol synthase, a late embryogenesis abundant protein, a dirigent-like protein, a histidine kinase receptor, avalencene synthase and a putative S-adenosyl-L-methionine:salicylic acid carboxyl methyltransferase. Conclusions: This set of up- and down-regulated genes characterize the late stages of berry ripening in the two cultivars studied, and are indirectly linked to wine quality. They might be used directly or indirectly to design immunological, biochemical or molecular tools aimed at the determination of optimal ripening in these cultivars.

Project description:Anthocyanins and flavonols are natural compounds that accumulate preferentially in grapevine flowers and fruits. They are among the most abundant flavonoids and play a very important role in grape and wine quality. In particular, they confer and stabilize colour and contribute to other organoleptic characteristics of the final product. Their complex profile in terms of concentration and relative abundance varies among cultivars and makes wine typicity. The synthesis of these compounds is mainly regulated at transcriptional level. Flavonoids accumulate at specific stages and in specific tissues during flower and berry development, as a consequence of the timely expression of the genes necessary for their synthesis. Although the general flavonoid pathway has been genetically and biochemically elucidated and the main determinants of colour have been identified, the molecular reasons of the fine variation among grape cultivars are still not completely understood. To shed light on this issue, extreme genotypes of a segregating population derived from the cross Syrah x Pinot Noir were characterized at transcriptional level. The transcriptome analysis along three berry developmental stages of these genotypes has allowed the identification of a large set of transcripts differentially modulated between the two groups. A population derived from M-bM-^@M-^XSyrahM-bM-^@M-^Y x M-bM-^@M-^XPinot NoirM-bM-^@M-^Y consisting of 170 F1 individuals plus the parental lines was characterized for the content of flavonols and anthocyanins in the skins of mature berries (38E-L; 18M-BM-0Brix). Based on the biochemical data, 4 high- and 4 low-flavonol producers (HFPs and LFPs: F1 16, F1 56, F1 63, F1 223 and F1 64, F1 256, F1 260, PN), two of which having also either very high or very low anthocyanin content (HAPs and LAPs: F1 63, F1 223 and F1 256, F1 260), were selected for gene expression analysis. A representative sample for each individual (one biological replicate) was collected at three berry developmental stages (hard green berry (33E-L, PV), veraison (35E-L, 50% coloured berries, VER) and maturity (38E-L, 18M-BM-0Brix, MAT)) during the 2007 season.

Project description:Noble rot results from atypical infections of ripe grape berries by Botrytis cinerea. Unlike bunch rot, noble rot promotes favorable changes in grape berries and accumulation of secondary metabolites that enhance wine grape quality. Noble rot-infected berries of SÃ©millon, a white-skinned variety, were collected over three years from a commercial vineyard at the same time fruit were harvested for botrytized wine production. Transcriptomic and metabolomic data were integrated to identify pathways associated with distinct stages of noble rot. Botrytis induced the expression of known key regulators of pathways in secondary metabolism associated with berry ripening. The activation by Botrytis during noble rot of metabolic pathways associated with berry ripening was further supported by comparisons with transcriptomes of red-skinned varieties at vÃ©raison. A prominent and common outcome of noble rot and berry ripening was the enhancement of the phenylpropanoid metabolism. Induced synthesis of stilbenes, flavonoids, and anthocyanins was supported by both transcriptional and metabolite analyses. Enzyme assays and targeted gene expression analyses of samples from the three distinct years confirmed that the activation of central and peripheral phenylpropanoid pathways is a consistent hallmark of noble rot. Finally, we show that the impact of noble rot on grape metabolism is still detectable in botrytized wines. These results demonstrate that despite the late stage of terminal senescence of a plant organ, a biotic stress can cause a major reprogramming of plant metabolism leading, in case of noble rot, to the synthesis of important metabolites for grape berry flavor and aroma. The experimental design consists of 4 treatments, berries at 3 distinct stages of noble rot and berries without apparent symptoms of infection. From each treatment a total of 4 biological replicates were sequenced with RNAseq, each replicate corresponded to independent pools of 10-15 berries harvested from adjacent grapevines.

Dataset Information

A grapevine anthocyanin acyltransferase, transcriptionally regulated by VvMYBA, can produce most acylated anthocyanins present in grape skins

Publications

A Grapevine Anthocyanin Acyltransferase, Transcriptionally Regulated by VvMYBA, Can Produce Most Acylated Anthocyanins Present in Grape Skins.

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