Stages Of Berry Development Research Articles

Ontogenic Resistance to Uncinula necator Varies by Genotype and Tissue Type in a Diverse Collection of Vitis spp.

Berries of grapevine (Vitis spp.) have a limited window of susceptibility to Uncinula necator, the causal agent of grapevine powdery mildew, until the onset of ontogenic resistance approximately 2 to 3 weeks postbloom. This phenomenon has been demonstrated in several cultivars of V. vinifera and in V. labruscana 'Concord', which all exhibited a similar duration of susceptibility. To identify genetic variation for ontogenic resistance, we screened a diverse collection of Vitis species and interspecific hybrids maintained in the USDA-ARS cold-hardy Vitis germplasm collection in Geneva, NY. Of the 79 genotypes whose fruit clusters were screened for susceptibility to powdery mildew under field conditions, 50 exhibited a high level of constitutive resistance to powdery mildew and did not develop more than trace levels of disease when inoculated, irrespective of the stage of berry development at inoculation. Twenty-four genotypes exhibited a significant gain of resistance as berries aged. This ontogenic resistance was conserved across four species and several interspecific hybrids of Vitis spp., although the timing of the onset of ontogenic resistance varied by genotype. The mechanism of ontogenic resistance was examined for four genotypes. Similar to previous studies, ontogenic resistance greatly reduced the incidence of successful penetration. Despite the broad conservation of ontogenic resistance across species, one genotype (V. rupestris 'R-65-44') remained susceptible past the onset of ripening, over 1 month later than reported previously for V. vinifera and V. labruscana. Variation in the resistance phenotype was observed among the rachis, pedicels, and berries within clusters of the majority of genotypes studied. The genetic variation in ontogenic resistance, in particular the discovery of a genotype in which berries remain susceptible as they mature, will facilitate further study of the inheritance and molecular basis of ontogenic resistance.

Identification of grapevine aquaporins and expression analysis in developing berries

Aquaporins are membrane water channels that play critical roles in controlling the water content of cells and tissues. In this work, nine full-length cDNAs encoding putative aquaporins were isolated from grape berry cDNA libraries. A phylogenetic analysis conducted with 28 aquaporin genes identified in the grapevine genome and previously characterized aquaporins from Arabidopsis indicates that three cDNAs encode putative tonoplast aquaporins (TIPs) whereas six cDNAs belong to the plasma membrane aquaporin subfamily (PIPs). Specific probes designed on the 3' untranslated regions of each cDNA were used for the preparation of cDNA macroarray filters and in situ hybridization experiments. Macroarray data indicate that expression levels of most TIP and PIP genes depend on grape berry developmental stages and point out to a global decrease of aquaporin gene expression during berry ripening. In young berries, high expression of aquaporin genes was preferentially observed in dividing and elongating cells and in cells involved in water and solutes transport. Taken together, the data provided in this paper indicate that aquaporins are implicated in various physiological aspects of grape berry development.

Transcriptomic analysis of grape berry softening during ripening

<p style="text-align: justify;"><strong>Aims</strong>: The aim of this paper was to use recent transcriptomic tools available for grape in order to understand berry softening.</p><p style="text-align: justify;"><strong>Methods and results</strong>: A microarray bearing specific 50 mer oligonucleotide for 3,200 genes was used to study gene expression along 8 stages of berry development in Chardonnay and Shiraz berries. Transcripts corresponding to aquaporin genes and to genes involved in cell wall metabolism were studied in detail and ranked according to their pattern of expression.</p><p style="text-align: justify;"><strong>Conclusion</strong>: Several structural and regulatory genes whose expression pattern correlated with the late phases of ripening were identified. Significance and impact of study: This study provides a preliminary molecular basis to identify molecular markers of berry ripening.</p>

Composition and Wine Sensory Attributes of Chardonnay Musqué from Different Viticultural Treatments

ABSTRACT ‘Chardonnay Musqué’ vines in Beamsville, Ontario, were subjected in one trial to three treatments: (1) control (hedged only); (2) basal leaf removal (BLR) and cluster thinning and; (3) cluster thinning during five stages of berry development. Berries and musts from each treatment were analyzed for soluble solids (Brix), pH, titratable acidity (TA), as well as free and potential monoterpenes (FVT and PVT). Wines produced from each treatment were evaluated by descriptive analysis for aroma and flavor intensities. FVT and PVT of berries were higher in thinned vines compared to non-thinned vines. Cluster thinning at veraison yielded fruit with the highest FVT and PVT concentrations. Leaf-pulled vines produced fruit with increased pH, reduced TA and highest FVT and PVT. Wines from BLR and thinning treatments generally had higher muscat and floral/perfumy aromas, and could be separated based on overall quality. The chemical and sensory data were incorporated into a multiple regression model used to construct a grape quality model for aromatic white Vitis vinifera grape cultivars in the Niagara Peninsula. The model developed was able to predict overall quality based on Brix, pH, and berry FVT and PVT concentration. The model was partially validated by correlations between berry FVT and PVT vs. floral and muscat aromas in wines from three previous vintages. This model has potential for use to create a more equitable payment schedule for growers contracted to wineries for the purchase of high-quality grapes.

Transcriptomic and metabolite analyses of Cabernet Sauvignon grape berry development.

BackgroundGrape berry development is a dynamic process that involves a complex series of molecular genetic and biochemical changes divided into three major phases. During initial berry growth (Phase I), berry size increases along a sigmoidal growth curve due to cell division and subsequent cell expansion, and organic acids (mainly malate and tartrate), tannins, and hydroxycinnamates accumulate to peak levels. The second major phase (Phase II) is defined as a lag phase in which cell expansion ceases and sugars begin to accumulate. Véraison (the onset of ripening) marks the beginning of the third major phase (Phase III) in which berries undergo a second period of sigmoidal growth due to additional mesocarp cell expansion, accumulation of anthocyanin pigments for berry color, accumulation of volatile compounds for aroma, softening, peak accumulation of sugars (mainly glucose and fructose), and a decline in organic acid accumulation. In order to understand the transcriptional network responsible for controlling berry development, mRNA expression profiling was conducted on berries of V. vinifera Cabernet Sauvignon using the Affymetrix GeneChip® Vitis oligonucleotide microarray ver. 1.0 spanning seven stages of berry development from small pea size berries (E-L stages 31 to 33 as defined by the modified E-L system), through véraison (E-L stages 34 and 35), to mature berries (E-L stages 36 and 38). Selected metabolites were profiled in parallel with mRNA expression profiling to understand the effect of transcriptional regulatory processes on specific metabolite production that ultimately influence the organoleptic properties of wine.ResultsOver the course of berry development whole fruit tissues were found to express an average of 74.5% of probes represented on the Vitis microarray, which has 14,470 Unigenes. Approximately 60% of the expressed transcripts were differentially expressed between at least two out of the seven stages of berry development (28% of transcripts, 4,151 Unigenes, had pronounced (≥2 fold) differences in mRNA expression) illustrating the dynamic nature of the developmental process. The subset of 4,151 Unigenes was split into twenty well-correlated expression profiles. Expression profile patterns included those with declining or increasing mRNA expression over the course of berry development as well as transient peak or trough patterns across various developmental stages as defined by the modified E-L system. These detailed surveys revealed the expression patterns for genes that play key functional roles in phytohormone biosynthesis and response, calcium sequestration, transport and signaling, cell wall metabolism mediating expansion, ripening, and softening, flavonoid metabolism and transport, organic and amino acid metabolism, hexose sugar and triose phosphate metabolism and transport, starch metabolism, photosynthesis, circadian cycles and pathogen resistance. In particular, mRNA expression patterns of transcription factors, abscisic acid (ABA) biosynthesis, and calcium signaling genes identified candidate factors likely to participate in the progression of key developmental events such as véraison and potential candidate genes associated with such processes as auxin partitioning within berry cells, aroma compound production, and pathway regulation and sequestration of flavonoid compounds. Finally, analysis of sugar metabolism gene expression patterns indicated the existence of an alternative pathway for glucose and triose phosphate production that is invoked from véraison to mature berries.ConclusionThese results reveal the first high-resolution picture of the transcriptome dynamics that occur during seven stages of grape berry development. This work also establishes an extensive catalog of gene expression patterns for future investigations aimed at the dissection of the transcriptional regulatory hierarchies that govern berry development in a widely grown cultivar of wine grape. More importantly, this analysis identified a set of previously unknown genes potentially involved in critical steps associated with fruit development that can now be subjected to functional testing.

The diversity of pathogenesis-related proteins decreases during grape maturation

It was recently shown that wines contain typically a huge diversity of structurally similar polypeptides that exhibit a high degree of homology to pathogenesis-related (PR) proteins. This observation suggested the existence of one or a few precursors in mature grapes, common to most or all the wine PR proteins. Limited proteolysis and chemical modification of the precursor(s) during fruit ripening and winemaking could then generate the large number of distinct wine polypeptides. However, the patterns of PR proteins extracted from grape berries regularly harvested from the onset of development until maturity did not confirm the previous hypothesis. Two different methodologies, involving 2-D immunoblotting and a combination of FPLC cation/anion exchange chromatographies with 1-D immunoblotting, indicate that the total concentration of PR proteins is increased but its diversity is reduced from the early stages of berry development until maturity. These results indicate that PR proteins are synthesized in a wide variety of forms from the early stages of grape development, eliminating the hypothesis previously formulated on the existence of one or few precursors common to the wine proteins.

Expression of three expansin genes during development and maturation of Kyoho grape berries

Expansins are cell-wall-localized proteins that induce loosening of isolated plant cell walls in vitro in a pH-dependent manner, but exhibit no detectable hydrolase or transglycosylase activity. Three putative expansin cDNAs, Vlexp1, Vlexp2, and Vlexp3 were isolated from a cDNA library made from mature berries of the Kyoho grape. Expression profiles of the 3 genes were analyzed throughout berry development. Accumulation of the Vlexp3 transcript was closely correlated with berry softening, and expression of this gene was detected before véraison and markedly increased at véraison (onset of berry softening). Expression of Vlexp3 was berry-specific. Vlexp1 and Vlexp2 mRNA accumulation began during the expansion stage of berry development and expression increased for both genes during ripening. Vlexp1 and Vlexp2 mRNA was detected in leaf, tendril and flower tissues and Vlexp2 mRNA was additionally detected in root and seed tissues. These findings suggest that the three expansin genes are associated with cell division or expansion and berry ripening. Vlexp3, in particular, is most likely to play a role in grape berry softening at véraison.

Studies with Crisp-textured Blueberries

Over the past two decades, selections that produce crisp-textured blueberries have been noted by breeders. Research was conducted to determine how these selections differ from standard cultivars. Four blueberry clones with crisp texture were compared, using firmness, with 94 advanced selections from the University of Florida blueberry breeding program. The clones, tested for berry firmness with an Instron machine, produced a normal distribution. The crisp clones were at the high end of the distribution, but were not qualitatively different from other firm-fruited selections. Firmness was tested during final stages of berry development to determine if crisp clones softened more slowly than standard cultivars. In both 2003 and 2004, firmness decreased greatly from the white to pink stages of development, with slower loss of firmness thereafter. Crisp and commercial clones were similar in the timing of firmness loss. Berries from six crisp clones and four firm commercial cultivars were subjected to shear cell tests to see if the two groups could be distinguished. Shear cell tests from early and late harvests in the same year showed good agreement. Three of the four crisp clones were much higher in shear force than the other clones tested. A consumer sensory panel was conducted to determine if the average person could distinguish between the berries of crisp and standard cultivars. Ninety-five subjects were given two samples each of crisp and non-crisp blueberries, and asked to designate the one sample they thought the most crisp. Seventy-five subjects chose one of the two crisp clones and 20 chose one of the standard clones. This research indicates that crisp texture in blueberry exists and is recognizable and repeatable, but is difficult to objectively define.

Survival and growth of Aspergillus carbonarius on wine grapes before harvest

Aspergillus carbonarius, the primary OTA-producing species in Australia, was inoculated onto the surface of Chardonnay and Shiraz bunches at pre-bunch closure, veraison and pre-harvest during the 2002–03 and 2003–04 seasons. Mean A. carbonarius counts decreased between pre-bunch closure and veraison, and increased between veraison and pre-harvest. Increases in A. carbonarius counts from veraison onwards were most marked in Chardonnay bunches during 2003–04; such bunches comprised more berries and were heavier than in 2002–03. Bunches with no berry damage yielded low A. carbonarius counts at pre-harvest and harvest. Exposure to direct sunlight over several days reduced viability of A. carbonarius spores supported on filter membranes by 10 5, despite the spores having thick, heavily melanised walls. The estimated cumulative UV exposure for that period was 10 mWh. Thus, UV radiation may be a contributory factor to the decline of A. carbonarius spores on berry surfaces, particularly in the early stages of berry development.

Seasonal Development of Ontogenic Resistance to Downy Mildew in Grape Berries and Rachises

ABSTRACT Clusters of Vitis vinifera and V. labrusca are reported to become resistant to Plasmopara viticola at stages of development ranging from 1 to 6 weeks postbloom. It has been suggested that resistance is associated with loss of the infection court as stomata are converted to lenticels, but the time of onset, cultivar variation, and seasonal variation in ontogenic resistance has remained uncertain, as has the comparative susceptibility of stem tissue within the fruit cluster. In New York, we inoculated clusters of V. vinifera cvs. Chardonnay and Riesling and V. labrusca cvs. Concord and Niagara at stages from prebloom until 5 to 6 weeks postbloom. Berries were infected and supported profuse sporulation until 2 weeks postbloom, and pedicel tissue remained susceptible until 4 weeks postbloom. Although berries on later-inoculated clusters failed to support sporulation, discoloration and necrosis of berry tissues was often noted, and necrosis of the pedicel within such clusters often led to further discoloration, shriveling, reduced size, or loss of berries. When the epidermis of discolored berries that initially failed to support sporulation was cut, the pathogen emerged and sporulated through incisions, indicating that lack of sporulation on older symptomatic berries was due to infection at an early stage of berry development followed by conversion of functional stomata to lenticels during latency. We repeated the study on Chardonnay and Riesling vines in South Australia and found that the period of berry and rachis susceptibility was greatly increased. The protracted susceptibility of the host was related to the increased duration and phenological heterogeneity of bloom and berry development in the warmer climate of South Australia. The time of onset and subsequent expression of ontogenic resistance to P. viticola may thus be modified by climate and should be weighed in transposing results from one climatic area to another. Our results can be used to refine forecast models for grapevine downy mildew to account for changes in berry and rachis susceptibility, and to focus fungicide application schedules upon the most critical periods for protection of fruit.

Anthocyanidin Reductase Gene Expression and Accumulation of Flavan-3-ols in Grape Berry

Proanthocyanidins, which are polymers and oligomers of flavan-3-ol units, are important components of grape for red winemaking and accumulate in the berry skins and seeds. Major flavan-3-ol units of grape proanthocyanidins are (-)-epicatechin and (-)-epigallocatechin. It was recently reported that (-)-epicatechin and (-)-epigallocatechin were biosynthesized from corresponding anthocyanidins by anthocyanidin reductase (ANR). In the current study, we obtained a genomic sequence of the ANR gene of <i>Vitis vinifera</i> cv. Cabernet Sauvignon (<i>VvANR</i>). The deduced amino acid sequence of <i>VvANR</i> conserved the characteristic sequence of ANR of other plants. Southern blot analysis showed that grape ANR is probably encoded by a single copy gene in its haploid genome. Real-time quantitative-PCR using berry skins and seeds showed that the mRNA of <i>VvANR</i> accumulates at the early stage of berry development and then decreases toward the ripening stage. Our analysis and other reports show that proanthocyanidins accumulate in the berry skins and seeds before veraison, especially during the early stage of development, and then decrease in concentration during ripening. Thus, the change of mRNA accumulation substantially coincides with the change of proanthocyanidin accumulation in the berry skins and seeds. These results indicate that at least a part of (-)-epicatechin and (-)-epigallocatechin biosynthesis is probably controlled by the transcription of <i>VvANR</i>.

Influence of Ethanol Concentration on the Extraction of Color and Phenolic Compounds from the Skin and Seeds of Tempranillo Grapes at Different Stages of Ripening

The aim of this paper is to study how grape ripeness and ethanol concentration affect the extraction of color and phenolic compounds from skins and seeds during the maceration/fermentation process. Simulated maceration assays were carried out with the grapes at three stages of berry development (vitis vinifera cv. Tempranillo) and different percentages of ethanol in the maceration media. Both ripeness and ethanol content have a considerable effect on the extraction of color and phenolic compounds. Of these two factors, ripeness increases the extractability most. The presence of ethanol in the medium facilitates anthocyanin and especially proanthocyanidin extraction, but it also decreases copigmentation phenomena, which can decrease the color intensity. The higher the ethanol concentration is in the maceration media, the higher the astringency of proanthocyanidins.

VvHT1 encodes a monosaccharide transporter expressed in the conducting complex of the grape berry phloem

The accumulation of sugars in grape berries requires the co-ordinate expression of sucrose transporters, invertases, and monosaccharide transporters. A monosaccharide transporter homologue (VvHT1, Vitis vinifera hexose transporter 1) has previously been isolated from grape berries at the veraison stage, and its expression was shown to be regulated by sugars and abscisic acid. The present work investigates the function and localization of VvHT1. Heterologous expression in yeast indicates that VvHT1 encodes a monosaccharide transporter with maximal activity at acidic pH (pH 4.5) and high affinity for glucose (K(m)=70 muM). Fructose, mannose, sorbitol, and mannitol are not transported by VvHT1. In situ hybridization shows that VvHT1 transcripts are primarily found in the phloem region of the conducting bundles. Immunofluorescence and immunogold labelling experiments localized VvHT1 in the plasma membrane of the sieve element/companion cell interface and of the flesh cells. The expression and functional properties of VvHT1 suggests that it retrieves the monosaccharides needed to provide the energy necessary for cell division and cell growth at an early stage of berry development.

Species ofPestalotiopsisand related genera occurring on grapevines in Australia

Descriptions of several appendage-bearing coelomycetes such as Pestalotiopsis and related genera occurring on grapevines in Australia are given. Species isolated included Pestalotiopsis uvicola, P. menezesiana, Seirnatosporium hysterioides, Truncatella angustata, and Sporocadus rhododendri. Infection studies showed that berries of grapevines were infected by P. uvicola more readily at later stages of berry development than at the earlier stages.

Effects of Grape Berry Developmental Stages on Ammonium Nitrate-enhanced Penetration of Gibberellin A3

The effects of ammonium nitrate (AMN) on the penetration of Gibberellin A3 (GA3) into berries of `Kyoho' (Vitis labruscana Bailey) grape during berry development were studied. Treatment solutions of GA3 (100 ng·μL-1) and GA3 + AMN (20 millimolar concentration) were applied to the surface of grape berries under field conditions. The amount of GA3 penetrated was assayed using dwarf rice (Oryza sativa L., cv. Tan-ginbozu). At full bloom, the addition of AMN significantly enhanced GA3 penetration 24, 48 ad 72 hours after application by 13%, 16% and 21% of the applied GA3, respectively, representing a 1.7- to 2.4-fold increase over GA3 alone. At 4 weeks after full bloom (WAFB) at 24 hours after application, 20% of the applied GA3 penetrated in the presence of AMN compared to 15% in the absence of AMN. From varaison (7 WAFB) to maturity (10 WAFB), GA3 penetration decreased, from 6% to 2%, respectively, in the presence of AMN, and from 3% to 1% in the absence of AMN. The addition of AMN to the GA3 solution increased GA3 penetration relative to GA3 alone at all berry developmental stages. On the other hand, Cuticular wax density on the berry surface at 4 WAFB was 1.10 μg·mm-2, 5.8-fold greater than at full bloom (0.19 μg·mm-2). The thickness of the epidermal tissue doubled during the first 2 WAFB, but was maintained almost constant over the next 6 weeks. GA3 penetration was more closely related to the cuticular wax levels than the epidermal tissue thickness.

Analysis of tannins in seeds and skins of Shiraz grapes throughout berry development

The flavan-3-ol and proanthocyanidin composition of both seeds and skin of Vitis vinifera L. cv. Shiraz grapes was determined by reversed-phase HPLC after acetone extraction and acid-catalysis in the presence of excess phloroglucinol. Samples were taken at weekly intervals from fruit-set until commercial harvest. The main period of proanthocyanidin accumulation in grape seeds occurred immediately after fruit-set with maximum levels observed around veraison. Over two seasons there was variation in both the timing and content of proanthocyanidins in seeds. In skin, proanthocyanidin accumulation occurred from fruit set until 1–2 weeks after veraison. Proanthocyanidin subunit composition was different in seeds and skin and changed during berry development but the mean degree of polymerisation of the tannin polymers in skins was higher than in the seeds at all stages of berry development. Proanthocyanidin levels in both seeds and skin decreased between veraison and harvest. Additional proanthocyanidin subunits were released when the residues remaining after acetone extraction were subjected to direct acid-catalysis in the presence of phloroglucinol. In the seeds, these accounted for much of the post-veraison decrease, but not in grape skin. At harvest, 75% of extractable berry proanthocyanidin was in the seeds. Accumulation of proanthocyanidins in the seeds appears to be independent of that in the skins, but in both tissues synthesis occurs early in berry development and maximum levels are reached around veraison.

Relationships between endogenous polyamines, cellular structure and arrested growth of grape berries

The condition known as ‘millerandage’ occurs when the growth of grape berries is interrupted early in their development. By harvest, berries in the same bunch will be different sizes, and some will be particularly small. Anatomical studies have revealed that interrupted growth can occur at different stages of berry development, and hormonal factors might be involved. Polyamines are one class of hormones that play an important role in plant morphogenesis, but analysis of polyamine content and composition indicated that berries of bunches with millerandage had the same polyamine composition as those at different stages of development. However, there were differences in relationships between wall-bound polyamine, especially wall-bound DAP, and arrested growth of berries. One key cytological difference was the negative PAS staining of cell walls in very small and in mid-size berries. In biochemical terms, wall-bound polyamine (and in particular wall-bound DAP content), was higher in berries from bunches with millerandage than in normal berries during their development. The present study therefore clearly demonstrates a positive correlation between wall-bound polyamine, especially wall-bound DAP, and arrested growth of berries in bunches with millerandage.

Composition of grape skin proanthocyanidins at different stages of berry development.

The composition of grape (Vitis vinifera L. cv. Shiraz) skin proanthocyanidins has been determined at different stages of berry development. Beginning approximately 3 weeks after fruit set and concluding at commercial ripeness, the composition of isolated skin proanthocyanidins was determined using the following analytical techniques: elemental analysis, UV-Vis absorption spectroscopy, reversed-phase HPLC after acid-catalysis in the presence of excess phloroglucinol, gel permeation chromatography, electrospray ionization mass spectrometry (ESI-MS), and (13)C NMR. On the basis of these analyses, berry development was correlated with an increase in proanthocyanidin mean degree of polymerization, an increase in the proportion of (-)-epigallocatechin extension subunits, and increases in the level of anthocyanins associated with the proanthocyanidin fraction. Additionally, data acquired from ESI-MS of the isolates following acid-catalysis in the presence of excess phloroglucinol is consistent with pectin-bound proanthocyanidins.

Influence of water deficits on grape berry growth

The effects of early and late water deficits on pericarp cell division and enlargement of Syrah berries ( Vitis vinifera L.) was determined by DNA extraction and quantification. Different periods and different levels of water deficit were applied between anthesis and maturity to grapevines growing under controlled water supply in two consecutive years. DNA extraction profiles showed that water deficit did not affect cell division. Reduction of berry size and berry weight was caused exclusively by a decrease of pericarp volume, independent of the intensity of the water deficit or the stage of berry development. Decreased cell volume as a result of an early water deficit from flowering to veraison was irreversible. These results support the hypothesis that early water deficits modify the structural properties of the cell components and consequently cell wall extensibility, thereby limiting the subsequent enlargement of pericarp cells.

Isolation of mitochondrial malate dehydrogenase and phosphoenolpyruvate carboxylase cDNA clones from grape berries and analysis of their expression pattern throughout berry development

Summary Malate accumulation in the grape berry, which takes place until the onset of ripening (veraison), is thought to occur mainly due to the combined activities of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH), which convert phosphoenolpyruvate to malate, via oxaloacetate. The rapid decrease in malate content during ripening has usually been attributed to its degradation by malic enzyme (ME) but it has also been related to MDH reverse reaction. Enzymological studies suggest that malate metabolism throughout berry development is controlled, at least partially, by the regulation of the level and/or activity of these enzymes. However, the mechanism by which the enzyme level is controlled is not clear. In an attempt to find out whether the developmental control of enzyme activity involves regulation of gene expression, we isolated PEPC, MDH, and ME eDNA clones from grape berries, and followed their expression pattern throughout berry development. PEPC transcript was detected only during the early stages of berry development, while acid accumulated, whereas both MDH and ME transcript levels peaked in the young berry, declined towards the onset of ripening, and were induced again during ripening when there was a major reduction in acidity. The developmental changes in the mRNA levels of the three genes correlated well with the changes in enzyme activity reported previously. These findings may suggest that the control of malate metabolism throughout berry growth involves developmental regulation of PEPC, MDH, and ME transcript availability.