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Anthocyanins and proanthocyanidins are considered to be essential secondary metabolites in grapes and are used to regulate metabolic processes, while miRNAs are involved in their synthesis of anthocyanins and proanthocyanidins to regulate metabolic processes. The present research work was carried out to investigate the underlying regulatory mechanism of target genes in the grape cultivars 'Italia' and 'Benitaka'. miRNA and transnscriptomic sequencing technology were employed to characterize both the profiles of miRNAs and the transcripts of grape peels at 10 and 11 weeks post flowering (10 wpf and 11 wpf). The results revealed that the expression level of vvi-miR828a in 'Italia' at 10 and 11 wpf was significantly higher than that in 'Benitaka'. miRNA-seq analysis predicted MYBPA1 to be the target gene of vvi-miR828a. In transcriptome analysis, the expression level of the VvMYBPA1 gene in 'Benitaka' was significantly higher than that in 'Italia'; in addition, the TPM values (expression levels) of VvMYBPA1 and miR828a also showed an evident negative correlation. The determination of the proanthocyanidin (PA) content in 'Italia' and 'Benitaka' peels at 11 wpf demonstrated that the PA content of 'Benitaka' was significantly higher than that of 'Italia'. The outcomes of RT-qRCR analysis exhibited that the expression levels of the VdPAL, VdCHS, VdCHI, VdDFR, VdMYB5b, VdANR, and VdMYBPA1 genes related anthocyanin and proanthocyanidin pathways were reduced, while the expression levels of all of the above genes were increased after the transient expression of the VvMYBPA1 vector into grape leaves. The results of the transient overexpression experiment of vvi-miR828a before the veraison period of strawberry fruits showed that vvi-miR828a can significantly slow down the coloration of strawberries. The vvi-miR828a negatively regulates the accumulation of proanthocyanidins in grape fruits by inhibiting the expression of VvMYBPA1. [ABSTRACT FROM AUTHOR]

The most common bud sport trait in grapevines is the change in color of grape berry skin, and the color of grapes is mainly developed by the composition and accumulation of anthocyanins. Many studies have shown that MYBA is a key gene regulates the initiation of bud sport color and anthocyanin synthesis in grape peels. In the current study, we used berry skins of 'Italia', 'Benitaka', 'Muscat of Alexandria', 'Flame Muscat', 'Rosario Bianco', 'Rosario Rosso', and 'Red Rosario' at the véraison stage (10 weeks post-flowering and 11 weeks post-flowering) as research materials. The relative expressions of genes related to grape berry bud sport skin color were evaluated utilizing RNA-Seq technology. The results revealed that the expressions of the VvMYBA1/A2 gene in the three red grape varieties at the véraison stage were higher than in the three white grape varieties. The VvMYBA1/A2 gene is known to be associated with UFGT in the anthocyanin synthesis pathway. According to the results, VvMYBA1/A2 gene expression could also be associated with the expression of LDOX. In addition, a single gene (gene ID: Vitvi19g01871) displayed the highest expressions in all the samples at the véraison stage for the six varieties. The expression of this gene was much higher in the three green varieties compared to the three red ones. GO molecular function annotation identified it as a putative metallothionein-like protein with the ability to regulate the binding of copper ions to zinc ions and the role of maintaining the internal stable state of copper ions at the cellular level. High expression levels of this screened gene may play an important role in bud sport color of grape berry skin at the véraison stage. [ABSTRACT FROM AUTHOR]

To investigate the deeper coloring mechanism of berry, the 'Benitaka' (Be) grape, ABA treatment on 'Benitaka' (Be (ABA)), and its deeper coloring bud mutation 'Brasil' (Br) grape were compared three weeks post-ABA treatment (11 weeks post-flowering, 200 mg/g ABA). Firstly, the ABA-treated group exhibited a deeper coloring at three weeks post-ABA treatment than the 'Brasil'. Deeper color in 'Brasil' was caused by higher content of peonidin-3-O-monoglucoside, malvidin-3-O-monoglucoside, and malvidin-3-O-coumarylglucoside, while the deeper color in ABA-treated group was mainly caused by higher content of cyanidin-3-O-monoglucoside and peonidin-3-O-monoglucoside. In addition, the results revealed that 'Brasil' showed deeper coloring than 'Benitaka' was probably due to the higher expression of the VvmybA1 and VvmybA1-1 genes, similar with ABA-treated group. Compared with 'Benitaka', the distinction between the ABA-treated group and 'Brasil' was the expression of VvmybA1 gene. The gene expression was delayed in the ABA-treated group until three weeks post treatment. The VvmybA1 gene and transcription factor play an important role in the anthocyanin biosynthesis, and showed the difference in expressions of the VvmybA1 and VvmybA1-1 gene during different period of time probably due to different kind of anthocyanins. Based on these results, a possible mechanism of anthocyanins biosynthesis was established to elaborate the reason for the deeper coloring in ABA-treated 'Benitaka' and 'Brasil' grapes. [ABSTRACT FROM AUTHOR]

Highlights • Dormancy is an essential stage of development in deciduous plants that allows them to tolerate the unfavorable environment. • During different dormancy stages, transcripts related to ABA and GA signaling showed differential expression pattern. • ABA and GA contents showed variation at three different dormancy stages. • This study will offer a useful approach to understand dormancy mechanism using pathway based transcriptomic approach. Abstract Dormancy is an essential stage of development in perennial plants that allows them to tolerate against unfavorable climatic conditions. Based on RNA-seq analysis, we compared the level of transcripts related to Gibberellins (GA) and Abscisic acid (ABA) at three different dormancy stages, i.e. summer buds (C1), para -dormancy (C2), and endo -dormancy (C3). Our results revealed a prominent up-regulation of GA and ABA signaling transcripts at different dormancy stages. Most of the transcripts related to protein phosphatase 2C (PP2C) showed down-regulatory behavior during C2 vs C3. In C1 vs C3, three transcripts related to PYR/PYLs were up-regulated while in C2 vs C3, only one had expressed the low transcript level. Four (SnRK2) related transcripts had exhibited down-regulation in case of C2 vs C3. Six transcripts encoding DELLA proteins in GA signaling pathway showed down-regulation in C1 vs C3 while ten transcripts were up-regulated in case of C2 vs C3. Nine transcripts encoding GID2 proteins were up-regulated in C1 vs C3 whereas six transcripts were down-regulated in C1 vs C3, respectively. The lower ABA content was observed at C3 stage as compared to other two stages whereas GA3 content was higher at C3 stage than C2 stage. The expression profiles depicted that the transcripts related to ABA and GA signaling were involved in dormancy mechanism. Based on these results we can speculate that ABA and GA pathways act as regulatory switches to regulate grape bud dormancy. [ABSTRACT FROM AUTHOR]

Grapevine ( Vitis vinifera L.) is considered to be one of the most popular and widespread fruit crops in the world. Numerous value added products are prepared from grape fruit and investments are being made to establish new viticulture region (Hoff et al., 2017; Imran et al., 2017). CPPU [forchlorfenuron N-(2-chloro-4-pyridyl)-N-phenylurea] is a synthetic cytokine-like plant regulator which promotes grape berry set and development. The influence of CPPU [forchlorfenuron N-(2-chloro-4-pyridyl)-N-phenylurea] on berry development of ‘Shine Muscat’ ( Vitis labruscana Bailey × V vinifera L.) grapes was evaluated under field conditions. A concentration response was observed over a range of 0, 5, and 10 mg L −1 CPPU that was applied to fruitlets (mean diameter 6 mm) at 2 weeks after full bloom. Gas-chromatography mass-spectrometry (GC–MS) revealed that volatile compounds such as terpenoids and aromatics; especially linalool, geraniol and benzyl alcohols, were greatly reduced in CPPU-treated grapes. In contrast, aliphatics, such as hexanol, were increased in CPPU-treated berries. RNA sequencing (RNA-Seq) was conducted to identify differentially expressed genes (DEGs) that were induced by CPPU, especially those related to volatile biosynthesis. A total of 494, 1237, and 1085 DEGs were detected in CPPU0-vs-CPPU5, CPPU0-vs-CPPU10, and CPPU5-vs-CPPU10 treatments, respectively. The results were compared against two databases (Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG)) to annotate gene descriptions and assign a pathway to each gene. GO covers three domains: biological processes, molecular functions and cellular components. Pathway enrichment annotation demonstrated that highly ranked genes were associated with the fatty acid degradation and biosynthesis, phenylpropanoid metabolism and biosynthesis, carotenoid biosynthesis, and plant hormone signal transduction. Analysis with qRT-PCR of twelve selected transcripts validated the data obtained by RNA-seq. Additionally, we also found that genes such as CCDs (carotenoid cleavage dioxygenase), LOX (lipoxygenase), GGDP reductase (geranylgeranyl diphosphate reductase), PAL (phenylalanine ammonia-lyase) and some hormones related genes, were closely involved in the formation of volatiles compounds in CPPU treated berries. In summary, our results provide the first sequential transcriptomic atlas of CPPU treated grape berries which significantly increases our understanding of volatile metabolites and biosynthesis pathways in grape affected by CPPU. [ABSTRACT FROM AUTHOR]

Using an RNA sequencing (RNA-seq) approach, we analyzed the differentially expressed genes (DEGs) and physiological behaviors of "Manicure Finger" grape plantlets grown in vitro under white, blue, green, and red light. A total of 670, 1601, and 746 DEGs were identified in plants exposed to blue, green, and red light, respectively, compared to the control (white light). By comparing the gene expression patterns with the growth and physiological responses of the grape plantlets, we were able to link the responses of the plants to light of different spectral wavelengths and the expression of particular sets of genes. Exposure to red and green light primarily triggered responses associated with the shade-avoidance syndrome (SAS), such as enhanced elongation of stems, reduced investment in leaf growth, and decreased chlorophyll levels accompanied by the expression of genes encoding histone H3, auxin repressed protein, xyloglucan endotransglycosylase/hydrolase, the ELIP protein, and microtubule proteins. Furthermore, specific light treatments were associated with the expression of a large number of genes, including those involved in the glucan metabolic pathway and the starch and sucrose metabolic pathways; these genes were up/down-regulated in ways that may explain the increase in the starch, sucrose, and total sugar contents in the plants. Moreover, the enhanced root growth and up-regulation of the expression of defense genes accompanied with SAS after exposure to red and green light may be related to the addition of 30 g/L sucrose to the culture medium of plantlets grown in vitro. In contrast, blue light induced the up-regulation of genes related to microtubules, serine carboxypeptidase, chlorophyll synthesis, and sugar degradation and the down-regulation of auxin-repressed protein as well as a large number of resistance-related genes that may promote leaf growth, improve chlorophyll synthesis and chloroplast development, increase the ratio of chlorophyll a (chla)/chlorophyll b (chlb), and decrease the ratio of carbohydrates to proteins in plants. Although exposure to red and green light seems to impose "shade stress" on the plantlets, growth under blue light is comparable to growth observed under white or broad-spectrum light. [ABSTRACT FROM AUTHOR]

Volatile compounds are considered to be essential for the flavor and aroma quality of grapes. Thidiazuron (TDZ) is a commonly used growth regulator in grape cultivation that stimulates larger berries and prevents fruit drop. This study was conducted to investigate the effect of TDZ on the production of aroma volatiles and to identify the key genes involved in the terpene biosynthesis pathways that are affected by this compound. Treatment with TDZ had a negative effect on the concentration of volatile compounds, especially on monoterpenes, which likely impacts the sensory characteristics of the fruit. The expression analysis of genes related to the monoterpenoid biosynthesis pathways confirmed that treatment with TDZ negatively regulated the key genes DXS1, DXS3, DXR, HDR, VvPNGer and VvPNlinNer1. Specifically, the expression levels of the aforementioned genes were down-regulated in almost all berry development stages in the TDZ-treated samples. The novel results from the present study can be used to aid in the development of food products which maintain the flavor quality and sensory characteristics of grape. Furthermore, these findings can provide the theoretical basis that can help to optimize the utilization of TDZ for the field production of grapes at a commercial scale. [ABSTRACT FROM AUTHOR]

Hydrogen cyanamide (HC) is an agrochemical compound that is frequently used to break bud dormancy in grapevines grown under mild winter conditions globally. The present study was carried out to provide an in-depth understanding of the molecular mechanism associated with HC releasing bud dormancy in grapevines. For this purpose, RNA-seq based transcriptomic and tandem mass tag (TMT)-based proteomic information was acquired and critically analyzed. The combined results of transcriptomic and proteomic analysis were utilized to demonstrate differential expression pattern of genes at the translational and transcriptional levels. The outcome of the proteomic analysis revealed that a total of 7135 proteins (p-value ≤ 0.05; fold change ≥ 1.5) between the treatments (HC treated versus control) were identified, out of which 6224 were quantified. Among these differentially expressed proteins (DEPs), the majority of these proteins were related to heat shock, oxidoreductase activity, and energy metabolism. Metabolic, ribosomal, and hormonal signaling pathways were found to be significantly enriched at both the transcriptional and translational levels. It was illustrated that genes associated with metabolic and oxidoreductase activity were mainly involved in the regulation of bud dormancy at the transcriptomic and proteomic levels. The current work furnishes a new track to decipher the molecular mechanism of bud dormancy after HC treatment in grapes. Functional characterization of key genes and proteins will be informative in exactly pinpointing the crosstalk between transcription and translation in the release of bud dormancy after HC application. [ABSTRACT FROM AUTHOR]

Bud dormancy is an essential and complex physiological process in perennial plants. Abscisic acid (ABA) is the major hormone regulating bud dormancy, however, the gene, SHORT VEGETATIVE PHASE (SVP) also plays a pivotal role. The combined regulation of SVP and ABA in the endodormancy network remains poorly characterized. In the present study, we demonstrate the growth inhibitory functions of VvSVP3 by its overexpressing it in tobacco and poplar. VvSVP3 -overexpressing poplar plants prematurely stopped growing under short day, exhibiting delayed bud break in early spring. VvSVP3 regulates ABA, the gibberellic acid (GA) pathway, and the callose synthesis to promote dormancy within its network. In addition, exogenous application of ABA positively affects VvSVP3 expression. A transcriptomics and proteomics combined approach identified that VvPYL9 is a target gene of VvSVP3 , which directly binds to a CArG motif in the VvPYL9 promoter to activate its expression. In summary, our results revealed the feedback regulation between VvSVP3 gene, ABA metabolism, and the dormancy signaling pathway in grape. It also provides new insights into the functional role of callose and ABA regulation in dormancy. • VvSVP3 induces callose synthesis and VvPYL9 expression, and simultaneously negatively regulates the GA metabolic pathway to maintain dormancy. • VvSVP3 gene prevents premature budbreak during dormancy. • VvSVP3 functions in vivo by forming heterodimers with other VvSVP genes. [ABSTRACT FROM AUTHOR]