Grape Berry Ripening Research Articles

Berry ripening: recently heard through the grapevine

Grapevine (Vitis vinifera L.) is a non-climacteric fruit species used as table fruit, dried raisins, and for vinification (wines) and distillation (liquors). In recent years, our knowledge of the molecular basis of ripening regulation has improved. Water status, light conditions, and temperature may hasten, delay, or enhance ripening. Hormones seem to play a central role, as their concentrations change prior to and during ripening and in response to several environmental cues. The review summarizes recent data related to the molecular and hormonal control of grape berry development and ripening, with special emphasis on secondary metabolism and its response to the environment, and pinpoints some experimental limitations.

Expressed sequence tags (ESTs) analysis of the ripening Vitis amurensis cv. Shuang Hong berry skins

Vitis amurensis is a valuable resource for wine production. Ripening of the grape berry is the key phase which determines the composition of wine. To better understand the gene expression that manifest in V. amurensis berry skins during the ripening, cDNA library of V. amurensis berry skins was constructed. A total of 935 high quality expressed sequence tags (ESTs) were obtained from the library. These ESTs represent 636 unigenes, including 108 contigs and 528 singletons. The EST analysis was performed and genes were assigned to functional categories according to their primary BLAST match. Of these 25.35% were involved with metabolism, 6.27% with cell rescue and defense, 6.84% energy, 11.68% protein synthesis, 18.8% protein activity regulation, 11.11% cell structure, 7.98% transport, 6.27% transcription and the remaining 5.7% were signal transduction. The generated ESTs were characterized by the gene ontology analysis and were categorized according to its cellular component, molecular function and biological process. In the cDNA library, some genes are relevant to the biosynthesis of anthocyanins, while some genes are related to grape berry maturation.

ABCC1, an ATP Binding Cassette Protein from Grape Berry, Transports Anthocyanidin 3-O-Glucosides

Accumulation of anthocyanins in the exocarp of red grapevine (Vitis vinifera) cultivars is one of several events that characterize the onset of grape berry ripening (véraison). Despite our thorough understanding of anthocyanin biosynthesis and regulation, little is known about the molecular aspects of their transport. The participation of ATP binding cassette (ABC) proteins in vacuolar anthocyanin transport has long been a matter of debate. Here, we present biochemical evidence that an ABC protein, ABCC1, localizes to the tonoplast and is involved in the transport of glucosylated anthocyanidins. ABCC1 is expressed in the exocarp throughout berry development and ripening, with a significant increase at véraison (i.e., the onset of ripening). Transport experiments using microsomes isolated from ABCC1-expressing yeast cells showed that ABCC1 transports malvidin 3-O-glucoside. The transport strictly depends on the presence of GSH, which is cotransported with the anthocyanins and is sensitive to inhibitors of ABC proteins. By exposing anthocyanin-producing grapevine root cultures to buthionine sulphoximine, which reduced GSH levels, a decrease in anthocyanin concentration is observed. In conclusion, we provide evidence that ABCC1 acts as an anthocyanin transporter that depends on GSH without the formation of an anthocyanin-GSH conjugate.

Grape berry yeast communities: Influence of fungicide treatments

The yeast communities colonising grape berry surfaces were evaluated for the influence of fungicide treatments in an organic vineyard (copper/sulphur-based products) and a conventional vineyard (commonly used fungicides). Analysis of yeast abundance and diversity was carried out on grape berries and juice during fermentation, using culture-dependent and -independent approaches. Yeast abundance was as generally reported for mature grapes and it was slight higher from grapes treated with conventional fungicides. Initial grape samples showed less yeast species diversity in the organic vineyard compared with the conventional one. In both vineyards, the dominant yeast were Candida zemplinina and Hanseniaspora uvarum (>50%), respectively, typical species that colonise surfaces of mature grape berries. Metschnikowia pulcherrima was widely found in the conventional samples while it was only occasionally found in organic ones.Saccharomyces cerevisiae was isolated only at the end of natural fermentation (conducted in sterile condition), with lower levels in the organic samples. S. cerevisiae strains showed less intraspecies diversity in the organic samples (two genotypes), in comparison with the conventional samples (six genotypes).

Ripening of grape berries can be advanced or delayed by reagents that either reduce or increase ethylene levels.

Grape (Vitis vinifera L.) berries are considered to be nonclimacteric fruit as they do not exhibit a large rise in ethylene production or respiration rate at the onset of ripening (veraison). However, ethylene may still play a role in berry development and in ripening in particular. (2-Chloroethyl)phosphonic acid (CEPA), an ethylene-releasing reagent, delayed ripening when applied early in berry development. In agreement with a role for ethylene in controlling the timing of ripening, the application of an inhibitor of ethylene biosynthesis, aminoethoxyvinylglycine (AVG), advanced ripening, as did abscisic acid, when applied during the preveraison period. Applications of CEPA nearer to the time of veraison enhanced berry colouration. Changes in the expression of ethylene biosynthesis and receptor genes were observed throughout berry development. Transcript levels of some of these genes were increased by CEPA and decreased by AVG, suggesting changes in ethylene synthesis and perception during the preveraison period that might contribute to the biphasic response to CEPA (ethylene). The significant delay of ripening in field-grown grapes through the application of CEPA also indicates that this may be useful in controlling the timing of veraison, and therefore harvest date, in warmer climates.

ITRAQ-based protein profiling provides insights into the central metabolism changes driving grape berry development and ripening.

BackgroundGrapevine (Vitis vinifera L.) is an economically important fruit crop. Quality-determining grape components such as sugars, acids, flavors, anthocyanins, tannins, etc., accumulate in the different grape berry development stages. Thus, correlating the proteomic profiles with the biochemical and physiological changes occurring in grape is of paramount importance to advance in our understanding of berry development and ripening processes.ResultsWe report the developmental analysis of Vitis vinifera cv. Muscat Hamburg berries at the protein level from fruit set to full ripening. An iTRAQ-based bottom-up proteomic approach followed by tandem mass spectrometry led to the identification and quantitation of 411 and 630 proteins in the green and ripening phases, respectively. Two key points in development relating to changes in protein level were detected: end of the first growth period (7 mm-to-15 mm) and onset of ripening (15 mm-to-V100, V100-to-110). A functional analysis was performed using the Blast2GO software based on the enrichment of GO terms during berry growth.ConclusionsThe study of the proteome contributes to decipher the biological processes and metabolic pathways involved in the development and quality traits of fruit and its derived products. These findings lie mainly in metabolism and storage of sugars and malate, energy-related pathways such as respiration, photosynthesis and fermentation, and the synthesis of polyphenolics as major secondary metabolites in grape berry. In addition, some key steps in carbohydrate and malate metabolism have been identified in this study, i.e., PFP-PFK or SuSy-INV switches among others, which may influence the final sugar and acid balance in ripe fruit. In conclusion, some proteins not reported to date have been detected to be deregulated in specific tissues and developmental stages, leading to formulate new hypotheses on the metabolic processes underlying grape berry development. These results open up new lines to decipher the processes controlling grape berry development and ripening.

UV-B and abscisic acid effects on grape berry maturation and quality

This review provides an overview of existing literature on the effects of ultraviolet-B (UV-B) radiation and abscisic acid (ABA) on physiological and biochemical aspects affecting grape berry (Vitis vinifera L.) growth, maturation and their quality for winemaking. The UV-B (280-315 nm) comprises only a small fraction of sunlight that reaches the Earth's surface, but has enough energy to cause large photobiological effects on higher plants. The UV-B levels are greater in the tropics than in upper latitudes and also increase with altitude, hence some vineyards are exposed to high UV-B but photoprotection and repair mechanisms are usually sufficient to prevent the occurrence of damage in grapevine tissues. ABA is a phytohormone that, aside to control stomatal aperture, regulates acclimation to adverse environmental conditions, and controls grape berry maturation (non-climacteric). A promotive effect of UV-B on ABA biosynthesis has been found in grapevine leaves. Accumulation of phenols (namely phenolic acids, stilbenes and flavonoids) is an acclimation and protective response against UV-B, either directly by absorbing UV-B in epidermal tissues and/or by reducing its penetration through underlying tissues, or indirectly by scavenging free radicals so acting as antioxidants. High UV-B and ABA applications increase total phenols in grape berries, but those with higher antioxidant capacity (i.e. dihydroxylated anthocyanidins and flavonols like quercetin) are increased relatively more. These treatments also hasten berry sugar and phenol accumulation, but reduce berry growth and sugar per berry at harvest, and therefore decrease yield. The quality of grape berries for winemaking integrates various aspects, but for red wines, it has a high correlation with accumulation of phenolics stimulated by UV-B and ABA.

Expression of Structural Genes Related to Anthocyanin Biosynthesis of <i>Vitis amurensis</i>

The accumulation of anthocyanins in skins is one of the main features of red grape berry ripening. This research was designed to assess the changes in anthocyanin content in grape skins of V. amurensis and to explore mRNA transcriptions of 11 structural genes (PAL, CHS3, CHI1, F3H2, F3'H, F3'5'H, DFR, LDOX, UFGT, OMT and GST) related to anthocyanin biosynthesis during grape berry development, by the use of HPLC-MS/MS and real-time Q-PCR analysis. Accumulation of anthocyanins began at veraison, continued throughout the later berry development and reached a peak at maturity. Veraison is the time when the berries turn from green to purple. Expression of PAL, CHI1, and LDOX were up-regulated from 2 to 4 weeks after flowering (WAF), down-regulated from 6 WAF to veraison, whereas DFR was up-regulated at 8 WAF, and then up-regulated from veraison to maturity. The expression of these genes at the transcriptional level had a positive correlation with the content of anthocyanins from veraison to maturity. The CHS3, F3'5'H, UFGT, GST, and OMT were down-regulated from 2 WAF to veraison, and then up-regulated from veraison to maturity. The transcriptional expressions of the 11 structural genes also showed positive correlations with the anthocyanin content from veraison to maturity. Positive correlations were also observed between OMT transcriptional level and the content of methoxyl-anthocyanins and between F3'5'H transcriptional level and the content of delphinidin anthocyanins. F3H2 and F3'H expression was up-regulated at 2 WAF. F3H2 expression was down-regulated from 4 WAF to veraison and then up-regulated again from veraison to maturity. F3'H expression was down-regulated at 4 WAF and then up-regulated again from 6 WAF to maturity. F3'H transcriptional level was correlated positively with the cyanidin anthocyanin concentration from veraison to maturity. These results indicate that the onset of anthocyanin synthesis during berry development coincides with a coordinated increase in the expression of a number of genes in the anthocyanin biosynthetic pathway.

The expression pattern of β-glucosidase genes (VvBGs) during grape berry maturation and dehydration stress

In order to understand more about the role of β-glucosidase gene expression in modulating ABA level, the expression pattern of three cDNAs (VvBG1, VvBG2 and VvBG3) which encode β-glucosidase in ripening grape berries was analyzed in the presence or absence of dehydration stress. The results show that expression of these three VvBG genes was markedly different. Expression of VvBG1 and VvBG2 increased rapidly from veraison to reach a maximum at harvest or several days immediately before harvest, and coincident with ABA accumulation during berry development and ripening. However, expression of VvBG3 differed from VvBG1 and VvBG2 in that transcript levels declined from the early young fruit stage through veraison after which there was no further change. At 10 days before harvest, dehydration treatment of detached grape berries up-regulated the expression of VvBG1 and enhanced ABA accumulation whereas the expression of VvBG2 was down-regulated, VvBG3 was unaffected by dehydration stress. However, in the leaves, dehydration treatment up-regulated the expression of VvBG1 and stimulated the accumulation of ABA but down-regulated expression of VvBG2 and VvBG3. Based on the results obtained, it is concluded that the expression pattern of the three VvBGs is both temporal and tissue specific. Furthermore, expression of the VvBGs might play a role in the regulation of ABA content during berry ripening and in the response of berries to dehydration stress.

Study on differential expression of 1-aminocyclopropane-1-carboxylic acid oxidase genes in table grape cv. Thompson Seedless

As a consequence of the non-climacteric status of grapes (Vitis vinifera), ethylene biosynthesis and signal transduction have scarcely been studied in this fruit. In spite this drawback, the available information suggests a role for ethylene in ripening grape berries. In this work, we report the identification of three homologous genes that encode 1-aminocyclopropane-1-carboxylic acid oxidase (ACO), a key component of ethylene biosynthesis. A comparison of protein sequences revealed that all three VvACOs harbor a 2OG-Fe(II) oxygenase domain, which is typical of the ACO gene family; however, VvACO1 showed a higher amino acid sequence homology with VvACO2 than with VvACO3. The expression pattern of VvACOs and the effect of exogenous ethylene on their transcript accumulation were evaluated during table grape berry development in the “Thompson Seedless” cultivar. A peak in VvACO1 transcript accumulation levels was registered around veraison that was 4-fold higher than at harvest, and this peak was confirmed during a second season in grapes that were harvested from three different vineyards. An enhancement in ethylene production and VvACO genes transcript levels was observed in grapes sprayed with ethephon during berry development. However, VvACO1 transcripts reached the highest accumulation earlier than VvACO2 and VvACO3. Altogether, these data confirmed that ethylene may have a role in some aspects of the grape ripening process, and they also highlighted the potential use of some VvACO genes as molecular markers for identifying grape veraison stages in grapes.

Characterization of mitochondrial dicarboxylate/tricarboxylate transporters from grape berries

Grape berries (Vitis vinifera L fruit) exhibit a double-sigmoid pattern of development that results from two successive periods of vacuolar swelling during which the nature of accumulated solutes changes significantly. Throughout the first period, called green or herbaceous stage, berries accumulate high levels of organic acids, mainly malate and tartrate. At the cellular level fruit acidity comprises both metabolism and vacuolar storage. Malic acid compartmentation is critical for optimal functioning of cytosolic enzymes. Therefore, the identification and characterization of the carriers involved in malate transport across sub-cellular compartments is of great importance. The decrease in acid content during grape berry ripening has been mainly associated to mitochondrial malate oxidation. However, no Vitis vinifera mitochondrial carrier involved in malate transport has been reported to date. Here we describe the identification of three V. vinifera mitochondrial dicarboxylate/tricarboxylate carriers (VvDTC1-3) putatively involved in mitochondrial malate, citrate and other di/tricarboxylates transport. The three VvDTCs are very similar, sharing a percentage of identical residues of at least 83 %. Expression analysis of the encoding VvDTC genes in grape berries shows that they are differentially regulated exhibiting a developmental pattern of expression. The simultaneous high expression of both VvDTC2 and VvDTC3 in grape berry mesocarp close to the onset of ripening suggests that these carriers might be involved in the transport of malate into mitochondria.

Elevated Gene Expression inChalcone SynthaseEnzyme Suggests an Increased Production of Flavonoids in Skin and Synchronized Red Cell Cultures of North American Native Grape Berries

Anthocyanins are antioxidants and are among the natural products synthesized via the flavonoid biosynthesis pathway. Anthocyanins have been recommended for dietary intake in the prevention of cardiovascular diseases, cancer, and age-related conditions such as Alzheimer's disease or dementia. With an increasingly aging population in many parts of the world, strategies for the commercial production of in vitro synchronized red cell cultures as natural antioxidants will be a significant contribution to human medicine. Red pigmented fruits such as grapes (Vitis sp.) are a major source of bioavailable anthocyanins and other polyphenols. Since the level of antioxidants varies among cultivars, this study is the first one that phytochemically and genetically characterizes native grape cultivars of North America to determine the optimal cultivar and berry cells for the production of anthocyanins as antioxidants. Using real-time PCR and bioinformatics approaches, we tested for the transcript expression of the chalcone synthase (CHS) gene, an enzyme involved in the flavonoid and anthocyanin biosynthesis pathway, in different parts of physiologically mature grape berries and in vitro synchronized red cells. A low level of expression was recorded in berry flesh, compared with an elevated expression in berry skins and in vitro synchronized red cells, suggesting increased production of flavonoids in skin and cell cultures. This preliminary study demonstrates the potential of functional genomics in natural products research as well as in systematic studies of North American native grapes, specifically in muscadine (Vitis rotundifolia).

Reactions of grape varieties to climate changes in North East Slovenia

This work examined the trend of changes in temperature from 1950 to 2009 recorded by the Maribor meteorological station, and from 1980 to 2009 the dynamics of grape ripening of early-, medium late-, and late-ripening vine varieties in the Slovenian Styria wine-growing region in North East Slovenia. Based on the data associated with the content of soluble solids, total acidity, and the recommended date of harvest in a particular year, the trends towards shortening of the grapevine growing period were calculated. In general, temperature changes were more significant since 1980 than between 1950 and 1979. The mean annual and seasonal temperature significantly increased, i.e. 0.06°C per year. The growing season was shortened in all studied varieties from 15 to 27 days. Trends showed significantly decreasing content of total acidity, which can be considered explicitly as a consequence of higher temperatures during the growth period and ripening of grape berries. Grapes now ripen at temperatures which are approximately by 2°C higher than 30 years ago. Regarding the total acidity content of the late-ripening varieties, the influence of higher temperatures is positive. Minor changes were found in precipitations rates.  

Delaying Riesling grape berry ripening with a synthetic auxin affects malic acid metabolism and sugar accumulation, and alters wine sensory characters.

An improved understanding of the hormonal control of grape (Vitis vinifera L.) berry ripening and the ability to manipulate it are of interest scientifically and commercially. Grapes are nonclimacteric fruit with ethylene unlikely to have a principal role in berry ripening but there are several other hormones thought to be involved. In this work, a significant delay in Riesling berry ripening was achieved through preripening treatments with the synthetic auxin 1-naphthaleneacetic acid (NAA). The initiation of sugar accumulation was delayed and the rate of sugar accumulation was lower in NAA-treated fruit, resulting in a 15-day delay in harvest. NAA treatments also reduced the rate of decline in malic acid levels that occurs during ripening, and increased the synchronicity of malic acid and berry sugar accumulation. Sensory panel assessment revealed a significant difference between wine made from control and NAA-treated fruit. Analysis of the volatile composition of the wines' headspace showed that the concentration of several compounds was altered significantly by the NAA treatment. These data provide further support for the involvement of auxins in inhibiting ripening and suggest that auxin treatments may be useful in controlling both winery intake, and fruit and wine composition.

Morphoanatomical Symptomatology and Osmotic Behavior of Grape Berry Shrivel

Berry shrivel, a physiological disorder, adversely affects ripening of grape (Vitis vinifera L.) berries; however, its causes are unknown. We adopted a holistic approach to elucidate symptomatology, morphoanatomy, and osmotic behavior of grape berry shrivel. Berries from healthy and afflicted vines were analyzed compositionally and with various techniques of microscopy. Healthy berries developed all physical and compositional attributes desirable for wine-making. Conversely, berry shrivel berries were grossly metamorphosed manifested as shriveling of the pericarp, which paralleled with loss of membrane competence in the mesocarp cells causing its collapse and a loss of brush. The most intriguing observation was the presence of non-druse crystals. These berries had high osmotic potential (ψS) as a result of low accumulations of sugar and potassium. Nonetheless, the seed morphology, structure, and viability were similar to healthy seeds. Berry shrivel grotesquely modified grape berries both compositionally and structurally, which was paralleled by their inability to accumulate sugars followed by cell death in the mesocarp. Although the mechanisms of berry shrivel remain uncertain, our study provides valuable background information for generating suitable guidelines to minimize the incidences of berry shrivel and also to design future studies toward unraveling the mechanistic basis of berry shrivel.

Sucrose accumulation during grape berry and strawberry fruit ripening is controlled predominantly by sucrose synthase activity

SummaryPhloem unloading and the metabolism of sucrose largely determine the content and type of sugars which have important roles in the improvement of fruit quality. However, the molecular mechanisms underlying the accumulation of sucrose in grape berry and strawberry fruit remain unclear. The relative contents of sucrose (Suc), glucose (Glu), and fructose (Fru) were analysed, as well as the levels of expression of key genes involved in sucrose accumulation, including those for soluble acid invertase (SAI), cell wall invertase (CWI), sucrose synthase (SS), sucrose phosphate synthase (SPS), and sucrose transporter 1 (SUT1) during the ripening of both grape berry and strawberry fruit. The results showed that ‘Hamburg’ grape berry accumulated low amounts of sucrose, whereas, ‘Hongyan’ strawberry fruit accumulated high levels of sucrose. Transcription of CWI, SPS, and SUT1 increased rapidly in both fruit, while SAI transcript levels increased only slightly, and remained low, except for a large increase during early ripening in strawberry fruit. Interestingly, the levels of transcription and translation of the SS gene showed opposite patterns in the two types of fruit. High SS enzyme activity with low sucrose contents in grape berry, and low SS enzyme activity with high sucrose contents in strawberry fruit, suggest that SS plays a dominant role in sucrose accumulation during ripening in both types of fruit.

Comparative analysis of learning and meta-learning algorithms for creating models for predicting the probable alcohol level during the ripening of grape berries

The changes occurring in the dynamics of sugar concentration in grape berries are fairly significant during maturation, whereby they are commonly used as a marker of their development. In view of the importance this parameter has for wine producers, this paper designs several models for predicting the must’s probable alcohol level using both meteorological variables and those specific to the vineyard. Presentation is made of a comparative analysis of learning and meta-learning algorithms for the selection of variables and the design of useful predictive models for estimating this level. The models are designed according to data gathered at different locations within the Rioja Qualified Designation of Origin (DOC Rioja, Spain) under different climate conditions, as well as involving different grape varieties. The models designed in this study provide very good results, and following their validation by experts, they have been proven to make a major contribution to decision-making in vine growing. Finally, considering the indices of analysis studied, it has been observed that the ensemble-type model based on the Bagging algorithm with REPTree decision trees records the best results, with a root mean squared error (RMSE) of 8.1% and a correlation of 84.9%.

Acyl substrate preferences of an IAA-amido synthetase account for variations in grape (Vitis vinifera L.) berry ripening caused by different auxinic compounds indicating the importance of auxin conjugation in plant development

Nine Gretchen Hagen (GH3) genes were identified in grapevine (Vitis vinifera L.) and six of these were predicted on the basis of protein sequence similarity to act as indole-3-acetic acid (IAA)-amido synthetases. The activity of these enzymes is thought to be important in controlling free IAA levels and one auxin-inducible grapevine GH3 protein, GH3-1, has previously been implicated in the berry ripening process. Ex planta assays showed that the expression of only one other GH3 gene, GH3-2, increased following the treatment of grape berries with auxinic compounds. One of these was the naturally occurring IAA and the other two were synthetic, α-naphthalene acetic acid (NAA) and benzothiazole-2-oxyacetic acid (BTOA). The determination of steady-state kinetic parameters for the recombinant GH3-1 and GH3-2 proteins revealed that both enzymes efficiently conjugated aspartic acid (Asp) to IAA and less well to NAA, while BTOA was a poor substrate. GH3-2 gene expression was induced by IAA treatment of pre-ripening berries with an associated increase in levels of IAA-Asp and a decrease in free IAA levels. This indicates that GH3-2 responded to excess auxin to maintain low levels of free IAA. Grape berry ripening was not affected by IAA application prior to veraison (ripening onset) but was considerably delayed by NAA and even more so by BTOA. The differential effects of the three auxinic compounds on berry ripening can therefore be explained by the induction and acyl substrate specificity of GH3-2. These results further indicate an important role for GH3 proteins in controlling auxin-related plant developmental processes.

A DIGE-based quantitative proteomic analysis of grape berry flesh development and ripening reveals key events in sugar and organic acid metabolism

Grapevine (Vitis vinifera L.) is an economically important fruit crop. Quality-determining grape components, such as sugars, acids, flavours, anthocyanins, tannins, etc., are accumulated during the different grape berry development stages. Thus, correlating the proteomic profiles with the biochemical and physiological changes occurring in grape is of paramount importance to advance the understanding of the berry development and ripening processes. Here, the developmental analysis of V. vinifera cv. Muscat Hamburg berries is reported at protein level, from fruit set to full ripening. A top-down proteomic approach based on differential in-gel electrophoresis (DIGE) followed by tandem mass spectrometry led to identification and quantification of 156 and 61 differentially expressed proteins in green and ripening phases, respectively. Two key points in development, with respect to changes in protein level, were detected: end of green development and beginning of ripening. The profiles of carbohydrate metabolism enzymes were consistent with a net conversion of sucrose to malate during green development. Pyrophosphate-dependent phosphofructokinase is likely to play a key role to allow an unrestricted carbon flow. The well-known change of imported sucrose fate at the beginning of ripening from accumulation of organic acid (malate) to hexoses (glucose and fructose) was well correlated with a switch in abundance between sucrose synthase and soluble acid invertase. The role of the identified proteins is discussed in relation to their biological function, grape berry development, and to quality traits. Another DIGE experiment comparing fully ripe berries from two vintages showed very few spots changing, thus indicating that protein changes detected throughout development are specific.

Proteomic Analysis of Grape Berry Cell Cultures Reveals that Developmentally Regulated Ripening Related Processes Can Be Studied Using Cultured Cells

BackgroundThis work describes a proteomics profiling method, optimized and applied to berry cell suspensions to evaluate organ-specific cultures as a platform to study grape berry ripening. Variations in berry ripening within a cluster(s) on a vine and in a vineyard are a major impediment towards complete understanding of the functional processes that control ripening, specifically when a characterized and homogenous sample is required. Berry cell suspensions could overcome some of these problems, but their suitability as a model system for berry development and ripening needs to be established first.Methodology/Principal FindingsIn this study we report on the proteomic evaluation of the cytosolic proteins obtained from synchronized cell suspension cultures that were established from callus lines originating from green, véraison and ripe Vitis vinifera berry explants. The proteins were separated using liquid phase IEF in a Microrotofor cell and SDS PAGE. This method proved superior to gel-based 2DE. Principal component analysis confirmed that biological and technical repeats grouped tightly and importantly, showed that the proteomes of berry cultures originating from the different growth/ripening stages were distinct. A total of twenty six common bands were selected after band matching between different growth stages and twenty two of these bands were positively identified. Thirty two % of the identified proteins are currently annotated as hypothetical. The differential expression profile of the identified proteins, when compared with published literature on grape berry ripening, suggested common trends in terms of relative abundance in the different developmental stages between real berries and cell suspensions.ConclusionsThe advantages of having suspension cultures that accurately mimic specific developmental stages are profound and could significantly contribute to the study of the intricate regulatory and signaling networks responsible for berry development and ripening.