Dataset Information

MYB24 orchestrates terpene and flavonol metabolisms as light responses to anthocyanin depletion in grape variegated berries

ABSTRACT: The presence of naturally-occurring color mutants in plants has permitted the identification of many regulatory genes implicated in the synthesis of discrete metabolic compounds, mostly anthocyanins and carotenoids. Conversely, transcription factors that coordinate more than one specialized metabolic pathway seem challenging to screen from a forward genetics’ perspective. We explored the relationship between different branches of the phenylpropanoid and isoprenoid pathways while examining an infrequent berry skin color variegation in grapevine. Red and white berry skin sections were compared at the genetic, transcriptomic and metabolomic levels showing that light-responsive flavonols and monoterpenes increased in anthocyanin-depleted areas. We disclosed an enrichment of the corresponding pathways among up-regulated genes from white-skin sections, accompanied by increased expressions of flavonol regulators and the still uncharacterized MYB24 gene. We used DAP-seq to examine the in vitro binding of affinity‐purified MYB24 protein to genomic DNA and demonstrated its binding in the promoter regions of 22 terpene synthase genes, in addition to 32 photosynthesis/light-related genes, including the flavonol-regulator HYH. We confirmed the activation of TPS35 and HYH promoter-luciferase reporters in the presence of MYB24 and the grape bHLH-MYC2. The integration of several datasets allowed to define a list of high confidence targets, suggesting MYB24 as a modulator of light responses including the synthesis of flavonols and terpenes. The correspondence between MYB24 and monoterpenes in all conditions surveyed implies that this regulatory network is broadly triggered towards berry ripening, and that the absence of anthocyanin sunscreens accelerates its activation most likely in a dose-dependent manner due to increased radiation exposure.

ORGANISM(S): Vitis vinifera

PROVIDER: GSE198702 | GEO | 2025/03/15

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Flavonols constitute a group of flavonoids with important photoprotective roles in plants. In addition, flavonol content and composition greatly influences fruit quality. We previously demonstrated that the grapevine R2R3-MYB transcription factor VviMYBF1 promotes flavonol accumulation by inducing the expression of flavonol synthase (VviFLS1/VviFLS4), a key step of the initial flavonol pathway. Despite this, gene networks underlying flavonol modification in grapevine including both structural and regulatory genes remain poorly understood. In order to identify flavonol modifying genes and transcription factors acting downstream of VviMYBF1 a microarray-based transcriptome analysis was performed on grapevine hairy roots ectopically expressing VviMYBF1 or a Green Fluorescent Protein as control. VviFLS1 was induced in VviMYBF1 transgenic roots and flavonols, mainly quercetin 3-glucoside and quercetin 3-galactoside, accumulated significantly compared with control lines. Among the differentially expressed genes, potential flavonol-modifying enzymes with predicted rhamnosyltransferase (e.g. RhaT1) or glycosyltransferase (e.g. GT3) activities were identified. In addition, important transcription factors of the MYB and bZIP families such as the proanthocyanidin regulator VviMYBPA1 and the UV-B light responsive HY5 homologue VviHYH were significantly altered in their expression pattern by overexpression of VviMYBF1. In silico promoter sequence analysis confirmed that the significantly differentially expressed genes contained binding sites similar to known MYB recognition elements. Co-temporal expression analysis demonstrated positive correlation of VviMYBF1 and accumulation of glycosylated flavonols with VviGT3 and VviRhaT1 during berry development and in fruits ripened with different light and UV-B radiation conditions at field. These results show that VviMYBF1 overexpression led to the identification of novel genes of the flavonol pathway and that the flavonol modifying machinery can be influenced by agricultural practices to optimize flavonol composition in grapes.

Project description:Light conditions significantly influence grape berry ripening and the accumulation of phenolic compounds, but the underlying molecular basis remains partially understood. Here, we applied integrated transcriptomics and pathway-level metabolomics analyses to investigate the effect of cluster bagging during various developmental stages on phenolic metabolism in Cabernet Sauvignon grapes. Bagging treatments had limited effects on berry quality attributes at harvest and did not consistently affect phenolic acid biosynthesis between seasons. Significantly elevated flavan-3-ol and flavonol contents were detected in re-exposed berries after bagging during early-developmental stages, while bagging after véraison markedly inhibited skin anthocyanin accumulation. Several anthocyanin derivatives and flavonol glycosides were identified as marker phenolic metabolites for distinguishing bagged and non-bagged grapes. Coordinated transcriptional changes in the light signaling components CRY2 and HY5/HYHs, transcription regulator MYBA1, and enzymes LAR, ANR, UFGT and FLS4, coincided well with light-responsive biosynthesis of the corresponding flavonoids. The activation of multiple hormone signaling pathways after both light exclusion and re-exposure treatments was inconsistent with the changes in phenolic accumulation, indicating a limited role of plant hormones in mediating light/darkness-regulated phenolic biosynthesis processes. Furthermore, gene-gene and gene-metabolite network analyses discovered that the light-responsive expression of genes encoding bHLH, MYB, WRKY, NAC, and MADS-box transcription factors, and proteins involved in genetic information processing and epigenetic regulation such as nucleosome assembly and histone acetylation, showed a high positive correlation with grape berry phenolic accumulation in response to different light regimes. Altogether, our findings provide novel insights into the understanding of berry phenolic biosynthesis under light/darkness and practical guidance for improving grape features.

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:UV radiation (UV) alters secondary metabolism in the skin of Vitis vinifera L. berries, which may affect on the final composition of both, grapes and wines. We compared berry skin transcriptome and phenolic composition between Tempranillo berries grown in the presence or absence of solar UV in a mid-altitude Tempranillo vineyard. By analysing two different ripening degrees, expression of 121 genes was significantly altered. Functional enrichment identified that, principally, secondary metabolism-related transcripts were induced by UV, including VvFLS1, VvGT5 and VvGT6 flavonol biosynthetic genes induction. Concurrently, flavonol accumulation was the most evident impact of UV on the berry skin phenolic composition. Monoterpenoid biosynthetic transcripts were also up-regulated by UV, whereas induction of stilbenoid biosynthetic transcripts and stilbenes accumulation was probably induced by the joint action of UV and other condition under the UV-blocking filter, likely higher temperature. Among regulatory genes, VvMYBF1, VvMYB24 and three bHLH transcription factors were up-regulated by UV. Homologs to Arabidopsis UVR8-dependent UV-B-induced genes were also induced, including VvHY5-1, VvHY5-2 and VvRUP UV-B signalling genes. This suggests that the UV-B-specific signalling pathway is activated in the skin of grapes grown at low-medium altitudes. The biosynthesis and accumulation of UV-absorbing compounds that are appreciated for winemaking were almost specifically triggered, which indicates that viticultural practices increasing solar UV incidence may improve grape features important to wine production. A total of 12 samples were hybridized. Grape skin RNA from berries ripening under a UV-transmitting filter (FUV+) and a UV-blocking filter (FUV-) was compared. Berry skin of two different ripening stages was analysed on each UV treatment. All samples were harvested simultaneously and a NaCl series was used to select the ripening degree in a non-invasive way. Three biological replicates were analyzed for each sample.

Project description:Among environmental factors, temperature is the one that poses serious threats to viticulture in the present and future scenarios of global climate change. In this work, we evaluated the effects on berry ripening of two thermal regimes, imposed from veraison to harvest. Potted vines were grown in two air-conditioned greenhouses with High Temperature (HT) and Low Temperature (LT) regimes characterized by 26 and 21°C as average and 42 and 35°C as maximum air daily temperature, respectively. We conducted analyses of the main berry compositional parameters, berry skin flavonoids and berry skin transcriptome on HT and LT berries sampled during ripening. The two thermal conditions strongly differentiated the berries. HT regime increased sugar accumulation at the beginning of ripening, but not at harvest, when HT treatment contributed to a slight total acidity reduction and pH increase. Conversely, growing temperatures greatly impacted on anthocyanin and flavonol concentrations, which resulted as strongly reduced, while no effects were found on skin tannins accumulation. Berry transcriptome was analyzed with several approaches in order to identify genes with different expression profile in berries ripened under HT or LT conditions. The analysis of whole transcriptome showed that the main differences emerging from this approach appeared to be more due to a shift in the ripening process, rather than to a strong rearrangement at transcriptional level, revealing that the LT temperature regime could delay berry ripening, at least in the early stages. Moreover, the results of the in-depth screening of genes differentially expressed in HT and LT did not highlight differences in the expression of transcripts involved in the biosynthesis of flavonoids (with the exception of PAL and STS) despite the enzymatic activities of PALs and UFGT being significantly higher in LT than HT. This suggests only a partial correlation between molecular and biochemical data in our conditions and the putative existence of post-transcriptional and post-translational mechanisms playing significant roles in the regulation of flavonoid metabolic pathways and in particular of anthocyanins.

Dataset Information

MYB24 orchestrates terpene and flavonol metabolisms as light responses to anthocyanin depletion in grape variegated berries

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets