Project description: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.

Project description:MicroRNAs (miRNAs) play a important part in post-transcriptional gene regulation and have been shown to control many genes involved in various biological and metabolic processes. There have been extensive studies to discover miRNAs and analyze their functions in model plant species, such as Arabidopsis and rice and other plants. However, the number of miRNAs discovered in grape is relatively low and little is known about miRNAs responded gibberellin during fruit germination. In this study, a small RNA library from gibberellin grape fruits was sequenced by the high throughput sequencing technology. A total of 16,033,273 reads were obtained. 812,099 total reads representing 1726 unique sRNAs matched to known grape miRNAs. Further analysis confirmed a total of 149 conserved grapevine miRNA (Vv-miRNA) belonging to 27 Vv-miRNA families were validated, and 74 novel potential grapevine-specific miRNAs and 23 corresponding novel miRNAs* were discovered. Twenty-seven (36.5%) of the novel miRNAs exhibited differential QRT-PCR expression profiles in different development gibberellin-treated grapevine berries that could further confirm their existence in grapevine. QRT-PCR analysis on transcript abundance of 27 conserved miRNA family and the new candidate miRNAs revealed that most of them were differentially regulated by the gibberellin, with most conserved miRNA family and 26 miRNAs being specifically induced by gibberellin exposure. All novel sequences had not been earlier described in other plant species. In addition, 117 target genes for 29 novel miRNAs were successfully predicted. Our results indicated that miRNA-mediated gene expression regulation is present in gibberellin-treated grape berries. This study led to the confirmation of 101 known miRNAs and the discovery of 74 novel miRNAs in grapevine. Identification of miRNAs resulted in significant enrichment of the gibberellin of grapevine miRNAs and provided insights into miRNA regulation of genes expressed in grape berries. GSM604831 is the control for the gibberellin-treated sample.

Project description:MicroRNAs (miRNAs) play a important part in post-transcriptional gene regulation and have been shown to control many genes involved in various biological and metabolic processes. There have been extensive studies to discover miRNAs and analyze their functions in model plant species, such as Arabidopsis and rice and other plants. However, the number of miRNAs discovered in grape is relatively low and little is known about miRNAs responded gibberellin during fruit germination. In this study, a small RNA library from gibberellin grape fruits was sequenced by the high throughput sequencing technology. A total of 16,033,273 reads were obtained. 812,099 total reads representing 1726 unique sRNAs matched to known grape miRNAs. Further analysis confirmed a total of 149 conserved grapevine miRNA (Vv-miRNA) belonging to 27 Vv-miRNA families were validated, and 74 novel potential grapevine-specific miRNAs and 23 corresponding novel miRNAs* were discovered. Twenty-seven (36.5%) of the novel miRNAs exhibited differential QRT-PCR expression profiles in different development gibberellin-treated grapevine berries that could further confirm their existence in grapevine. QRT-PCR analysis on transcript abundance of 27 conserved miRNA family and the new candidate miRNAs revealed that most of them were differentially regulated by the gibberellin, with most conserved miRNA family and 26 miRNAs being specifically induced by gibberellin exposure. All novel sequences had not been earlier described in other plant species. In addition, 117 target genes for 29 novel miRNAs were successfully predicted. Our results indicated that miRNA-mediated gene expression regulation is present in gibberellin-treated grape berries. This study led to the confirmation of 101 known miRNAs and the discovery of 74 novel miRNAs in grapevine. Identification of miRNAs resulted in significant enrichment of the gibberellin of grapevine miRNAs and provided insights into miRNA regulation of genes expressed in grape berries. GSM604831 is the control for the gibberellin-treated sample. The mixture samples of young berries (one week after flowering) large berries (five week after flowering after flowering), and old berries (nine week after flowering) treated with gibberellin, respectively, were generated by deep sequencing, in triplicate, using Illumina 1G Genome Analyzer.

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.

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Vitis vinifera

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