Berry Development Research Articles

Grapevine Potassium Nutrition and Fruit Quality in the Context of Climate Change.

Potassium (K+) nutrition is of relevant interest for winegrowers because it influences grapevine growth, berry composition, as well as must and wine quality. Indeed, wine quality strongly depends on berry composition at harvest. However, K+ content of grape berries increased steadily over the last decades, in part due to climate change. Currently, the properties and qualities of many fruits are also impacted by environment. In grapevine, this disturbs berry properties resulting in unbalanced wines with poor organoleptic quality and low acidity. This requires a better understanding of the molecular basis of K+ accumulation and its control along grape berry development. This mini-review summarizes our current knowledge on K+ nutrition in relation with fruit quality in the context of a changing environment.

Comprehensive Sequence Analysis of IQD Gene Family and their Expression Profiling in Grapevine (Vitis vinifera).

The plant-specific IQ67-domain (IQD) protein family members are downstream targets of calcium sensors, known to regulate plant growth and lateral organ polarity, and basal defense response against environmental cues. No systematic study of IQD gene family has been performed on grapevine. The public availability of grapevine genome enables us to perform identification, phylogeny, chromosomal orientation, and gene structure analysis of the IQD genes in grapevine. We identified 49 VvIQD genes (VvIQD1–VvIQD49) and further classified them into eight subgroups based on phylogenetic relationships. The 49 VvIQD genes were assigned to 19 different chromosomal positions. The collinear relationship between grapevine and Arabidopsis IQDs (VvIQD and AtIQD), and within grapevine VvIQDs, was highly conserved. In addition, most of duplicated gene pairs showed Ka/Ks ratio less than 1.00, indicating purifying selection within these gene pairs, implying functional discrepancy after duplication. Transcription profiling of VvIQD genes shed light on their specific role in grapevine tissue and organ development. The qRT-PCR validation of the 49 VvIQD genes in grape berry tissue from cultivars with distinct berry shape during developmental phases suggested candidate genes involved in the shape of grape berries. The subcellular prediction of VvIQD22, VvIQD23, VvIQD38, and VvIQD49 genes validated their localization in the nucleus and plasma membrane. The VvIQD49 protein interaction with VvCaM2 was also verified by bimolecular fluorescence complementation (BiFC) analysis in the plasma membrane. Our findings will be valuable for the functional genomic studies for desirable shape development of grape berries.

Characterization and temporal–spatial expression analysis of LEC1 gene in the development of seedless berries in grape induced by gibberellin

Grape (Vitis vinifera L.), a commercial fruit crop, is profoundly sensitive to gibberellic acid (GA), however exogenous application can significantly induce seedless grape berries. Nevertheless, the underlying molecular mechanism of grape leafy cotyledon 1 (LEC1) on seedless induction remains intangible. Herein, the morphological changes of ‘Wink’ grape cultivar during berry development in response to GA treatments were recorded. To better comprehend the function of VvLEC1 in grape seedless berry induced by GA, the gene and protein sequence were determined by bioinformatics methods, of which motif elements analysis intimates the potential function in seed development. The expression level of VvLEC1 which was repressed by GA treatment, determined by RT PCR, exhibited highest up-regulation at four weeks after flowering in the seed. Furthermore, VvLEC1, a member of the nuclear factor Y subunit B (NF-YB-type) transcription factor, interacts with five proteins which belong to the NF-YC-type transcription factor by the prediction of protein interaction network, thus indicating their collective effects on the development of grape seed. Our research findings elucidate a novel molecular insight into the role of VvLEC1 responsive to GA in accentuating grapevine seed development, which is crucial for the molecular breeding of high-quality seedless grapes.

Genome-wide identification and analysis of B-BOX gene family in grapevine reveal its potential functions in berry development

BackgroundThe B-BOX (BBX) proteins are the class of zinc-finger transcription factors and can regulate plant growth, development, and endure stress response. In plants, the BBX gene family has been identified in Arabidopsis, rice, and tomato. However, no systematic analysis of BBX genes has been undertaken in grapevine.ResultsIn this study, 24 grapevine BBX (VvBBX) genes were identified by comprehensive bioinformatics analysis. Subsequently, the chromosomal localizations, gene structure, conserved domains, phylogenetic relationship, gene duplication, and cis-acting elements were analyzed. Phylogenetic analysis divided VvBBX genes into five subgroups. Numerous cis-acting elements related to plant development, hormone and/or stress responses were identified in the promoter of the VvBBX genes. The tissue-specific expressional dynamics of VvBBX genes demonstrated that VvBBXs might play important role in plant growth and development. The transcript analysis from transcriptome data and qRT-PCR inferred that 11 VvBBX genes were down-regulated in different fruit developmental stages, while three VvBBX genes were up-regulated. It is also speculated that VvBBX genes might be involved in multiple hormone signaling (ABA, ethylene, GA3, and CPPU) as transcriptional regulators to modulate berry development and ripening. VvBBX22 seems to be responsive to multiple hormone signaling, including ABA, ethylene GA3, and CPPU. Some VvBBX genes were strongly induced by Cu, salt, waterlogging, and drought stress treatment. Furthermore, the expression of VvBBX22 proposed its involvement in multiple functions, including leaf senescence, abiotic stress responses, fruit development, and hormone response.ConclusionsOur results will provide the reference for functional studies of BBX gene family, and highlight its functions in grapevine berry development and ripening. The results will help us to better understand the complexity of the BBX gene family in abiotic stress tolerance and provide valuable information for future functional characterization of specific genes in grapevine.

Auxin treatment of grapevine (Vitis vinifera L.) berries delays ripening onset by inhibiting cell expansion.

Auxin treatment of grape (Vitis vinifera L.) berries delays ripening by inducing changes in gene expression and cell wall metabolism and could combat some deleterious climate change effects. Auxins are inhibitors of grape berry ripening and their application may be useful to delay harvest to counter effects of climate change. However, little is known about how this delay occurs. The expression of 1892 genes was significantly changed compared to the control during a 48h time-course where the auxin 1-naphthaleneacetic acid (NAA) was applied to pre-veraison grape berries. Principal component analysis showed that the control and auxin-treated samples were most different at 3h post-treatment when approximately three times more genes were induced than repressed by NAA. There was considerable cross-talk between hormone pathways, particularly between those of auxin and ethylene. Decreased expression of genes encoding putative cell wall catabolic enzymes (including those involved with pectin) and increased expression of putative cellulose synthases indicated that auxins may preserve cell wall structure. This was confirmed by immunochemical labelling of berry sections using antibodies that detect homogalacturonan (LM19) and methyl-esterified homogalacturonan (LM20) and by labelling with the CMB3a cellulose-binding module. Comparison of the auxin-induced changes in gene expression with the pattern of these genes during berry ripening showed that the effect on transcription is a mix of changes that may specifically alter the progress of berry development in a targeted manner and others that could be considered as non-specific changes. Several lines of evidence suggest that cell wall changes and associated berry softening are the first steps in ripening and that delaying cell expansion can delay ripening providing a possible mechanism for the observed auxin effects.

Proteomic and metabolomic profiling underlines the stage- and time-dependent effects of high temperature on grape berry metabolism.

Climate change scenarios predict an increase in mean air temperatures and in the frequency, intensity, and length of extreme temperature events in many wine-growing regions worldwide. Because elevated temperature has detrimental effects on berry growth and composition, it threatens the economic and environmental sustainability of wine production. Using Cabernet Sauvignon fruit-bearing cuttings, we investigated the effects of high temperature (HT) on grapevine berries through a label-free shotgun proteomic analysis coupled to a complementary metabolomic study. Among the 2,279 proteins identified, 592 differentially abundant proteins were found in berries exposed to HT. The gene ontology categories "stress," "protein," "secondary metabolism," and "cell wall" were predominantly altered under HT. High temperatures strongly impaired carbohydrate and energy metabolism, and the effects depended on the stage of development and duration of treatment. Transcript amounts correlated poorly with protein expression levels in HT berries, highlighting the value of proteomic studies in the context of heat stress. Furthermore, this work reveals that HT alters key proteins driving berry development and ripening. Finally, we provide a list of differentially abundant proteins that can be considered as potential markers for developing or selecting grape varieties that are better adapted to warmer climates or extreme heat waves.

A sense of place: transcriptomics identifies environmental signatures in Cabernet Sauvignon berry skins in the late stages of ripening

BackgroundGrape berry ripening is influenced by climate, the main component of the “terroir” of a place. Light and temperature are major factors in the vineyard that affect berry development and fruit metabolite composition.ResultsTo better understand the effect of “place” on transcript abundance during the late stages of berry ripening, Cabernet Sauvignon berries grown in Bordeaux and Reno were compared at similar sugar levels (19 to 26 °Brix (total soluble solids)). Day temperatures were warmer and night temperatures were cooler in Reno. °Brix was lower in Bordeaux berries compared to Reno at maturity levels considered optimum for harvest. RNA-Seq analysis identified 5528 differentially expressed genes between Bordeaux and Reno grape skins at 22°Brix. Weighted Gene Coexpression Network Analysis for all expressed transcripts for all four °Brix levels measured indicated that the majority (75%) of transcript expression differed significantly between the two locations. Top gene ontology categories for the common transcript sets were translation, photosynthesis, DNA metabolism and catabolism. Top gene ontology categories for the differentially expressed genes at 22°Brix involved response to stimulus, biosynthesis and response to stress. Some differentially expressed genes encoded terpene synthases, cell wall enzymes, kinases, transporters, transcription factors and photoreceptors. Most circadian clock genes had higher transcript abundance in Bordeaux. Bordeaux berries had higher transcript abundance with differentially expressed genes associated with seed dormancy, light, auxin, ethylene signaling, powdery mildew infection, phenylpropanoid, carotenoid and terpenoid metabolism, whereas Reno berries were enriched with differentially expressed genes involved in water deprivation, cold response, ABA signaling and iron homeostasis.ConclusionsTranscript abundance profiles in the berry skins at maturity were highly dynamic. RNA-Seq analysis identified a smaller (25% of total) common core set of ripening genes that appear not to depend on rootstock, vineyard management, plant age, soil and climatic conditions. Much of the gene expression differed between the two locations and could be associated with multiple differences in environmental conditions that may have affected the berries in the two locations; some of these genes may be potentially controlled in different ways by the vinegrower to adjust final berry composition and reach a desired result.

VvSWEET7 Is a Mono- and Disaccharide Transporter Up-Regulated in Response to Botrytis cinerea Infection in Grape Berries.

The newly-identified SWEETs are high-capacity, low-affinity sugar transporters with important roles in numerous physiological mechanisms where sugar efflux is critical. SWEETs are desirable targets for manipulation by pathogens and their expression may be transcriptionally reprogrammed during infection. So far, few plant SWEET transporters have been functionally characterized, especially in grapevine. In this study, in the Botrytis-susceptible variety “Trincadeira,” we thoroughly analyzed modifications in the gene expression profile of key SWEET genes in Botrytis cinerea-infected grape berries. VvSWEET7 and VvSWEET15 are likely to play an important role during fruit development and Botrytis infection as they are strongly expressed at the green and mature stage, respectively, and were clearly up-regulated in response to infection. Also, B. cinerea infection down-regulated VvSWEET17a expression at the green stage, VvSWEET10 and VvSWEET17d expression at the veraison stage, and VvSWEET11 expression at the mature stage. VvSWEET7 was functionally characterized by heterologous expression in Saccharomyces cerevisiae as a low-affinity, high-capacity glucose and sucrose transporter with a K m of 15.42 mM for glucose and a K m of 40.08 mM for sucrose. VvSWEET7-GFP and VvSWEET15-GFP fusion proteins were transiently expressed in Nicotiana benthamiana epidermal cells and confocal microscopy allowed to observe that both proteins clearly localize to the plasma membrane. In sum, VvSWEETs transporters are important players in sugar mobilization during grape berry development and their expression is transcriptionally reprogrammed in response to Botrytis infection.

Genome‑wide identification, characterization, and expression analysis of GDSL-type esterases/lipases gene family in relation to grape berry ripening

GDSL-type esterases/lipases (GELP) were a large subfamily of lipolytic enzymes which play important roles in plant growth, environment stress, and functional differentiation. Few was known about its function in fruit ripening. In this study, 83 VvGELPs were identified and divided into three clades and 11 subclades based on the phylogenic analysis. There are conserved gene structures and motif compositions for the members of the same subclade. 83 VvGELPs were unevenly distributed on 17 chromosomes, and most of the genes had five exons. Six sets of tandem duplication were detected, in which, only two sets of segmental duplication. Further analysis of the promoter regions of VvGELPs revealed the distinct presence of plant hormone-responsive, development-responsive, light-responsive and environment stress-responsive cis-acting elements. The expression analyses based on RNA-Seq and qRT-PCR in ‘Kyoho’ from the control and treatment with H2O2 showed that VvGELPs had different expression patterns during the grape berry development. VvGELP76 and VvGELP82 were highly expressed in all the development stage. Seven VvGELPs (VvGELP3, 30, 36, 43, 62, 70, 82) were up-regulated in 35 DPA, while down-regulated in 55 DPA. VvGELP29 was significantly down-regulated in 35 DPA and 55 DPA. The results indicated that VvGELPs were involved in grape berry ripening.

The accumulation profiles of terpene metabolites in three Muscat table grape cultivars through HS-SPME-GCMS

Aroma is an important parameter for table grapes and wines; terpenes are typical compounds in Muscat-type grape cultivars and can be easily perceived by humans because of their low olfactory threshold. Volatile terpenes contribute directly to the aroma character, while glycoside-bound terpenes are potential aromatic compounds and can be changed to their volatile forms via hydrolysis. With gas chromatography-mass spectrometry and a solid-phase microextraction method, an automatic data analysis platform was constructed; terpene compounds were identified and quantified from three table grape cultivars at three stages during berry development, and the raw data were deposited in MetaboLights. Terpene metabolite accumulation profiles are presented in this article for integrative analysis with the transcriptome data and phenotypic data to elucidate the important candidate genes and mechanism for terpene biosynthesis. Our method has applications in the identification and quantification of terpene compounds with very low or trace concentrations.

Comparative transcriptome analyses of a table grape ‘Summer Black’ and its early-ripening mutant ‘Tiangong Moyu’ identify candidate genes potentially involved in berry development and ripening

ABSTRACT Early ripening is an important desirable attribute for fruit crops. ‘Tiangong Moyu’, a bud mutant of the grape cultivar ‘Summer Black’ (Vitis vinifera L.× Vitis labrusca L.), ripens nearly 10 days earlier and shows earlier increase in fresh weight, sugar accumulation, and color change and faster decrease in titratable acid than ‘Summer Black’. To identify the genes controlling early fruit development and ripening in ‘Tiangong Moyu’, RNA-Seq profiles of the two cultivars were compared at five different berry developmental stages. Based on GO annotation and KEGG pathway enrichment analysis, the differentially expressed genes were clustered into various functional groups, including plant hormone signal transduction, transcription factors, anthocyanin-associated biosynthesis pathway, phenylpropanoid biosynthesis, plant–pathogen associated and plant–pathogen interaction, and ripening-related protein genes. Our results provided a global transcriptional profile of candidate genes involved in regulating berry development and ripening and a genetic basis for the understanding of grape berry ripening.

Stomatal Functioning and Its Influence on Fruit Calcium Accumulation in Northern Highbush Blueberry

Accumulation of calcium (Ca) in fruit is largely caused by transpiration and varies depending on the concentration of Ca in the xylem fluid. The objective of the present study was to evaluate the relationship between fruit stomatal functioning and Ca accumulation during different stages of development in northern highbush blueberry (Vaccinium corymbosum L.). Stomata were scarce on the berries and were concentrated primarily on the distal end near the calyx. The density of the stomata was greatest at petal fall, averaging 5 to 108 stomata/mm2 from the proximal end (pedicel end) to the distal end of the berries. Stomata were wide-open at the early green stage of berry development and had a slight deposit of wax along the guard cells. As the berries expanded during the initial period of rapid growth (stage I), most of the stomata remained near the distal segment of the berries; by the late green stage, almost none was found in the middle and proximal segments. The majority of these stomata were completely covered with wax when the berries began to change color and ripen (stage II and stage III). Stomatal conductance (gS) of the berries averaged 45 mmol·m−2·s−1 at petal fall and rapidly declined as the fruit developed. By the fruit coloring stage, conductance was low and remained less than 15 mmol·m−2·s−1 throughout the ripening period. In four cultivars, including Duke, Bluecrop, Aurora, and Elliott, Ca uptake in the berries increased rapidly during the early green stage; however, it slowed considerably between the late green and fruit coloring stages and stopped completely during fruit ripening. The results of this study strongly suggested that practices used to increase the Ca content of blueberries, such as the application of foliar fertilizers, should be performed early in the season during the first few weeks after flowering.

Early water stress effects on pollen viability, berry set and embryo development in cv. 'Syrah' (Vitis vinifera L.)

Early water deficit at bloom results in poor berry set and/or a grape yield reduction. The purpose of this work was to determine the effects of early water stress in a berry’s development. The experiment was carried out in a SupAgro ECOTRON System in Montpellier, France. Seven year- old ‘Syrah’ vines were used. The pot’s surface was protected from rainfall, and the growing medium was perlite+coarse sand with controlled drainage. The treatments were WS<sub>0</sub> (control): 4 l/day, WS<sub>1</sub>: 3 l/day, WS<sub>2</sub>: 2 l/day, and WS<sub>3</sub>: 1 l/day. The water deficit was carried out from the 17<sup>th</sup> to the 27<sup>th</sup> Eichhorn-Lorenz (E-L) stages. In order to emphasise details of the embryo development, a paraffin section method and technique was used. With the early water stress, there was no effect on the pollen viability and pollen germination ratios. The berry set ratio was reduced and the berry development were affected negatively by the early water stress. Between the 19<sup>th</sup> and the 27<sup>th</sup> E-L stages, an early water stress in ‘Syrah’ was noted, with decreases in the pre-dawn leaf water potential values below –0.8 MPa. The water deficit affected the berry growth and the development negatively.

Competitivness and prospects for development of berry production in Ukraine

The demand for raspberries and blackberries has risen sharply in Europe and North America in recent years. Ukraine is almost one third of the world’s black earth, a favorable climate for growing vegetables, fruits and berries, as well as a good ratio of daytime and night-time temperatures and optimal length of sunny day. Therefore, the authors consider that Ukraine could become a reliable supplier of berries in Europe and America. Berries will not give the same high gross production as cereals. But these products are perspective in terms of processing, value added and profitability for the manufacturer. Considering the strategic importance of growing berries in Ukraine the subject of the research is to study the competitiveness and prospects for production of berries in Ukraine. The conducted assessment of the status and prospects of growing berries shows that Ukraine has been steadily producing within the range of 130-135 thousand tons of berries in recent years. Due to the fact that the products of private households and horticultural societies are not actually taxed, they have significant competitive advantages over agricultural enterprises, which is one of the reasons for the curtailment of industrial horticulture in Ukraine. But, on the other hand, they are inferior to large enterprises because of not failing to implement sanitary, technical standards, certification etc. In order to ensure the competitiveness of domestic producers in the external market, berry producers need to be more actively involved in the process of improving product quality, since in Ukraine only five agribusinesses have a Global GAP certificate, which is a minimum condition for access to the EU market. According to the results of the study, the authors consider organic production of berries as another perspective direction for the development of domestic berries.

Characterization of VvSPL18 and Its Expression in Response to Exogenous Hormones during Grape Berry Development and Ripening

The sequence and structure of grape SBP-box-like18 (VvSPL18) were identified and characterized to explore its regulatory roles during grape berry development and ripening. Homologous conservation across diverse plant species was observed, and its potential function and modulated roles in grapes were investigated. The results showed that VvSPL18 has an ORF sequence of 1,137 bp, encodes 378 amino acids, and is located on chromosome 14 of grapevine. VvSPL18 has the closest relationship with its homolog in soybeans. The promoter of VvSPL18 contains cis-elements responsive to gibberellins (GA) and salicylic acid (SA), indicating that this gene might respond to these hormones involved in the modulation of grape berry. VvSPL18 is mainly distributed in the nucleus. Expression profiles showed that VvSPL18 is highly expressed only at the veraison stage of the grape berry and is slightly expressed in other phases. RNA-seq data also revealed that VvSPL18 might participate in the modulation of grape berry development and ripening. Treatment with diverse hormones demonstrated that abscisic acid (ABA) had almost no effect on its expression, whereas naphthalene acetic acid (NAA) significantly upregulated its expression at the veraison stage. We also found that VvSPL18 has a GA-responsive cis-element but no NAA-responsive cis-element. GA could promote the expression of VvSPL18 with a peak at an earlier stage than NAA, suggesting that VvSPL18 responds faster to GA than to NAA. This result indicates that VvSPL18 might modulate berry development at this phase through an ABA-independent pathway, and it might directly respond to GA, but indirectly to NAA. Our findings provide insights into the functions of VvSPL18 in mediating grape berry development and ripening.

The kinetics of grape ripening revisited through berry density sorting

Aim: In this study, ripening and heterogeneity in density-sorted berries were investigated, with the aim of more clearly understanding the kinetics of water uptake and sugar, acid and anthocyanin accumulation in the fruit of a new, disease-resistant hybrid.Methods and results: The 3184-1-9N hybrid, grown in a semi-arid climate in the South of France, was used. Its genotype is the result of several backcrosses of a Muscadinia ´ Vitis vinifera F1 hybrid with several V. vinifera varieties. From the end of the green plateau to the over-ripening stage, single berries were sampled weekly and sorted by density, to monitor the advancement of ripening and the heterogeneity of grapevine fruit development at population level. Fruit firmness, density, fresh weight, primary metabolite content (sugars and organic acids), secondary metabolite content (anthocyanins), potassium content and pH were measured in berries from each density class. The data showed that softening and hexose accumulation occurred before fruit pigmentation. Based on malic acid and anthocyanin concentration relative to sugar concentration in density-sorted grapes, malic acid breakdown or dilution was promoted and anthocyanin accumulation reduced in late- or slow-ripening berries. In the different population structures in two experimental plots, berries with similar sugar concentration showed considerable heterogeneity in terms of volume and anthocyanin content, whereas pH, potassium content and acid content showed much more homogeneous kinetics.Conclusions: During ripening, analysis of density-sorted berries provides useful information about sugar concentration heterogeneity and its relation with organic acid and anthocyanin content. The stage at which grapes can be considered ripe may be precisely determined through periodic determination of mean berry volume or weight, to detect the cessation of phloem unloading and the onset of berry shrivelling. However, ripening and shrivelling berries generally coexist in the harvested population. Asynchronous berry development and berry weight heterogeneity greatly complicate determination of the timing of developmental events that are regulated at the single-berry level. Therefore, analysis of individual berries would seem to be an indispensable component of investigations of berry growth and development.Significance and impact of the study: Plotting water uptake and solute accumulation relative to sugar accumulation (as an internal clock) provides an original way to display grapevine fruit development data. Analysis of density-sorted berries has identified the relatively invariant fruit features, such as the minimum concentration of tartaric acid, the stability of potassium accumulation and pH, and conversely, the huge variations in berry size.

Anatomical characteristics associated with different degrees of berry cracking in grapes

Grape berry cracking refers to the phenomenon of peel cracking that occurs during berry growth and development. It is related to be berry structure and the characteristics of the berry tissue. To study the relationship between berry-cracking and berry anatomical structure, 53 grape germplasm resources were selected. The ripening berry was soaked and cracked in vitro, after which the berry-cracking rate was measured and paraffin sections were prepared to analyze the structural parameters of different berry tissues. Berry cracking was found to be influenced by the shape of cuticle, the arrangement of epidermal cells and,subepidermal cells, and the thickness of cell layers. With regard to cuticle shape, grapes with local suberization had the highest cracking rate (58.33%), and those with a flat cuticle shape had the lowest rate (30.67%). Grape berries with a compact epidermal cell arrangement had the highest berry cracking rate (57.00%). As for subepidermal cell arrangement, the highest berry-cracking rates were observed in varieties with a looser arrangement (83.33%); and the lowest rates were found in varieties with a more compact subepidermal cell arrangement (32.33%). Correlation analysis between the grape berry-cracking rate and cell layer thickness showed that berry-cracking rate was negatively correlated with the thickness of the cuticle, epidermis, and subepidermis. Moreover, the cell shape and size parameters in the different cell layers may also affect the occurrence of berry cracking. Using paraffin sections to analyze cell structure characteristics, we can predict the cracking of grape berries, which would then provide theoretical support for further screening of germplasm resources to identify cracking-resistant berries.

Grape Flavonoid Evolution and Composition Under Altered Light and Temperature Conditions in Cabernet Sauvignon (Vitis vinifera L.).

The evolution of flavonoids under altered temperature and light conditions in the fruit zone was followed in Cabernet Sauvignon (Vitis vinifera L.) grapes during ripening. The study was conducted over two consecutive seasons in 2010/2011 and 2011/2012 comprising two main treatments in which the light quantity was manipulated in the bunch zone: (1) standard (STD) with no lateral shoot or leaf removal and (2) leaf removal west (LRW) treatment with leaf removal on the western side of the bunch zone. Furthermore, the light quality was altered by installing ultraviolet B-suppression sheets within the bunch zone in both seasons. Tannin evolution was dependent on the prevailing light quality/quantity and temperatures during berry development in a particular season. Grape seed tannin accumulation coincided with seed development and commenced at the early stages of berry development. Seed proanthocyanidin composition was not influenced by the treatments. The largest impact on proanthocyanidin accumulation and structure in the skin was due to seasonal variations highlighting the complex interaction between light quality and/or quantity across the two growing seasons and eventually the complex interaction with temperature. Flavonol accumulation was significantly influenced by the light quality, which is known to be the main abiotic driver of flavonol biosynthesis regulation. Anthocyanin concentration and content were largely dependent on the temperature and light quality in a particular season. Anthocyanin composition was altered by the season rather than the treatment.

Transcriptome profiling of \u2018Kyoho\u2019 grape at different stages of berry development following 5-azaC treatment

Background5-Azacytidine (5-azaC) promotes the development of ‘Kyoho’ grape berry but the associated changes in gene expression have not been reported. In this study, we performed transcriptome analysis of grape berry at five developmental stages after 5-azaC treatment to elucidate the gene expression networks controlling berry ripening.ResultsThe expression patterns of most genes across the time series were similar between the 5-azaC treatment and control groups. The number of differentially expressed genes (DEGs) at a given developmental stage ranged from 9 (A3_C3) to 690 (A5_C5). The results indicated that 5-azaC treatment had not very great influences on the expressions of most genes. Functional annotation of the DEGs revealed that they were mainly related to fruit softening, photosynthesis, protein phosphorylation, and heat stress. Eight modules showed high correlation with specific developmental stages and hub genes such as PEROXIDASE 4, CAFFEIC ACID 3-O-METHYLTRANSFERASE 1, and HISTONE-LYSINE N-METHYLTRANSFERASE EZA1 were identified by weighted gene correlation network analysis.Conclusions5-AzaC treatment alters the transcriptional profile of grape berry at different stages of development, which may involve changes in DNA methylation.

Functional Characterization of the Grapevine γ-Glutamyl Transferase/Transpeptidase (E.C. 2.3.2.2) Gene Family Reveals a Single Functional Gene Whose Encoded Protein Product Is Not Located in Either the Vacuole or Apoplast.

γ-glutamyl transferases/transpeptidases (E.C. 2.3.2.2, GGTs) are involved in the catabolism of many compounds that are conjugated to glutathione (GSH), which have a variety of roles. GSH can act as storage and transport vehicle for reduced sulfur; it is involved in the detoxification of xenobiotics and also acts as a redox buffer by utilizing its thiol residue to protect against reactive oxygen species, which accumulate in response to biotic and abiotic stress. Furthermore, many distinctive flavor and aroma compounds in Sauvignon blanc wines originate from odorless C5- and C6-GSH conjugates or their GGT catabolized derivatives. These precursors are then processed into their volatile forms by yeast during fermentation. In many plant species, two or more isoforms of GGTs exist that target GSH-conjugates to either the apoplast or the vacuole. A bioinformatics approach identified multiple GGT candidates in grapevine (Vitis vinifera). However, only a single candidate, VvGGT3, has all the conserved residues needed for GGT activity. This is intriguing given the variety of roles of GSH and GGTs in plant cells. Characterization of VvGGT3 from cv. Sauvignon blanc was then undertaken. The VvGGT3 transcript is present in roots, leaves, inflorescences, and tendril and at equal abundance in the skin, pulp, and seed of mature berries and shows steady accumulation over the course of whole berry development. In addition, the VvGGT3 transcript in whole berries is upregulated upon Botrytis cinerea infection as well as mechanical damage to leaf tissue. VvGGT3-GFP fusion proteins transiently over-expressed in onion cells were used to study subcellular localization. To confirm VvGGT3 activity and localization in vivo, the fluorescent γ-glutamyl-7-amido-4-methylcoumarin substrate was added to Nicotiana benthamiana leaves transiently over-expressing VvGGT3. In combination, these results suggest that the functional VvGGT3 is associated with membrane-like structures. This is not consistent with its closely related functionally characterized GGTs from Arabidopsis, radish and garlic.