Different Stages Of Berry Development Research Articles

Diversity Analysis of Culturable Epiphytic Microbial Consortia of Table Grape Berry Surface

ABSTRACT The health and yield of grapes are affected by the microorganisms associated with the grapevine. The diversity of microorganisms present on the wine grape varieties is well defined whereas, the information associated with the microorganisms of table grape varieties remains scarce. In the present study, culture-dependent method was used to isolate the microbes present on the surface of the commercial white seedless table grape cultivar, Thompson Seedless at different stages of berry development. The microbial load of the grape berry surface increased as the berry progressed toward the ripening stage resulting in the identification of core bacteria (29), filamentous fungi (19) and yeast (3). A diversity analysis study also revealed that Cladosporium cladosporioides, was found in the vineyard on grapes from the early berry development stages, as an emerging pre-harvest pathogen. The study would help in understanding and exploiting the microbiota of table grape berry in agronomic and biotechnological applications.

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.

Transcriptomics of the grape berry shrivel ripening disorder

Key messageThe lower expression at veraison of several ripening master regulators “switch genes” can play a central role in the induction of the berry shrivel ripening physiological disorder in grapevine.Berry shrivel (BS) is a ripening physiological disorder affecting grape berry with visible symptoms appearing after veraison. Berry shrivel leads to shrinking berries with a reduced weight and a lower content of sugars and anthocyanins. In this study, for the first time a transcriptomic analysis coupled with selected metabolites quantification was undertaken to understand the metabolic modifications induced by the disorder. Different stages of berry development were considered including pre- and symptomatic berries. No metabolic alterations in the berry transcriptome and in the metabolite content was observed in pre-symptomatic and pre-veraison samples. Interestingly, at veraison, with still not visible symptoms appearing on the berry, a subset of genes, called switch genes previously suggested as master regulators of the ripening onset in grape berries, were strongly lower expressed in BS. Later during the ripening phase and with visible symptoms of the disorder, more than 3000 genes were differentially expressed. The genes up-regulated were related to hormone biosynthesis, response to stress and the phenylpropanoid pathway, while the genes down-regulated during ripening belonged mainly to the flavonoid pathway, and the sugar metabolism. In agreement, BS berries showed lower content of sugars and anthocyanins from the onset of veraison onward, while the amount of acids was not significantly affected. In conclusion, these results highlight a pivotal role of the switch genes in grapevine ripening, as well as their possible contribution to induce the ripening disorder berry shrivel, although it remains unclear whether this is part of the cause or consequences of the BS disorder.

Dynamics of partitioning of major sugars, total phenols and flavonoids in the juice of seven wine grape (Vitis spp.) cultivars during different stages of berry development

The juices of seven grapevine (wine) cultivars grown in the Fruit Research Farm, Department of Fruit Science, PAU Ludhiana, were analyzed for sugar, phenol and flavonoids at four different stages of berry development, in 2015 and 2016. When the unripe berries were almost in full size, the glucose, fructose and sucrose contents ranged from 1.650–4.433 g/100 ml, 1.030–2.940 g/100 ml and 0.063–1.043 g/100 ml in the year 2015 and 1.500–3.760 g/100 ml (2016), 0.703–2.757 g/100 ml and 0.023–1.030 g/100 ml in the year 2016, while the level of phenols and flavonoids was very low. At verasion sugar content increased slightly. However dramatic changes in all genotypes were recorded after verasion. In the final analysis the total sugar content varied from 20.293 g/100 ml (CBR)–26.087 g/100 ml (Merlot) in the year 2015 and 17.750 g/100 ml (Carolina Black Rose)–24.337 g/100 ml (Merlot) n the year 2016, and the phenol and total flavonoid content of mature berries range from 3.070 g/100 ml (Merlot)–4.967 g/100 ml (H-144) in the year 2015 and 2.296 g/100 ml–4.453 g/100 ml (H-144) in the year 2016. This study gives valuable information for further understanding the sugar, phenol and total flavonoid changes that occur in some grape cultivars during berry maturation. Therefore, the results are useful for research on biochemistry of grapes during berry development.

GA3 application in grapes (Vitis vinifera L.) modulates different sets of genes at cluster emergence, full bloom, and berry stage as revealed by RNA sequence-based transcriptome analysis

In grapes (Vitis vinifera L.), exogenous gibberellic acid (GA3) is applied at different stages of bunch development to achieve desirable bunch shape and berry size in seedless grapes used for table purpose. RNA sequence-based transcriptome analysis was used to understand the mechanism of GA3 action at cluster emergence, full bloom, and berry stage in table grape variety Thompson Seedless. At cluster emergence, rachis samples were collected at 6 and 24h after application of GA3, whereas flower clusters and berry samples were collected at 6, 24, and 48h after application at full bloom and 3-4mm berry stages. Seven hundred thirty-three genes were differentially expressed in GA3-treated samples. At rachis and flower cluster stage respectively, 126 and 264 genes were found to be significantly differentially expressed within 6h of GA3 application. The number of DEG reduced considerably at 24h. However, at berry stage, major changes occurred even at 24h and a number of DEGs at 6 and 24h were 174 and 191, respectively. As compared to upregulated genes, larger numbers of genes were downregulated. Stage-specific response to the GA3 application was observed as evident from the unique set of DEGs at each stage and only a few common genes among three stages. Among the DEGs, 67 were transcription factors. Functional categorization and enrichment analysis revealed that several transcripts involved in sucrose and hexose metabolism, hormone and secondary metabolism, and abiotic and biotic stimuli were enriched in response to application of GA3. A high correlation was recorded for real-time PCR and transcriptome data for selected DEGs, thus indicating the robustness of transcriptome data obtained in this study for understanding the GA3 response at different stages of berry development in grape. Chromosomal localization of DEGs and identification of polymorphic microsatellite markers in selected genes have potential for their use in breeding for varieties with improved bunch architecture.

Impacts of Grapevine Leafroll Disease on Fruit Yield and Grape and Wine Chemistry in a Wine Grape (Vitis vinifera L.) Cultivar.

Grapevine leafroll disease (GLD) is an economically important virus disease affecting wine grapes (Vitis vinifera L.), but little is known about its effect on wine chemistry and sensory composition of wines. In this study, impacts of GLD on fruit yield, berry quality and wine chemistry and sensory features were investigated in a red wine grape cultivar planted in a commercial vineyard. Own-rooted Merlot vines showing GLD symptoms and tested positive for Grapevine leafroll-associated virus 3 and adjacent non-symptomatic vines that tested negative for the virus were compared during three consecutive seasons. Number and total weight of clusters per vine were significantly less in symptomatic relative to non-symptomatic vines. In contrast to previous studies, a time-course analysis of juice from grapes harvested at different stages of berry development from symptomatic and non-symptomatic vines indicated more prominent negative impacts of GLD on total soluble solids (TSS) and berry skin anthocyanins than in juice pH and titratable acidity. Differences in TSS between grapes of symptomatic and non-symptomatic vines were more pronounced after the onset of véraison, with significantly lower concentrations of TSS in grapes from symptomatic vines throughout berry ripening until harvest. Wines made from grapes of GLD-affected vines had significantly lower alcohol, polymeric pigments, and anthocyanins compared to corresponding wines from grapes of non-symptomatic vines. Sensory descriptive analysis of 2010 wines indicated significant differences in color, aroma and astringency between wines made from grapes harvested from GLD-affected and unaffected vines. The impacts of GLD on yield and fruit and wine quality traits were variable between the seasons, with greater impacts observed during a cooler season, suggesting the influence of host plant × environment interactions on overall impacts of the disease.

Terpene evolution during the development of Vitis vinifera L. cv. Shiraz grapes

The flavour of wine is derived, in part, from the flavour compounds present in the grape, which change as the grapes accumulate sugar and ripen. Grape berry terpene concentrations may vary at different stages of berry development. This study aimed to investigate terpene evolution in grape berries from four weeks post-flowering to maturity. Grape bunches were sampled at fortnightly intervals over two vintages (2012–13 and 2013–14). In total, five monoterpenoids, 24 sesquiterpenes, and four norisoprenoids were detected in grape samples. The highest concentrations of total monoterpenoids, total sesquiterpenes, and total norisoprenoids in grapes were all observed at pre-veraison. Terpenes derived from the same biosynthetic pathway had a similar production pattern during berry development. Terpenes in grapes at harvest might not necessarily be synthesised at post-veraison, since the compounds or their precursors may already exist in grapes at pre-veraison, with the veraison to harvest period functioning to convert these precursors into final products.

Metabolic and molecular analyses of white mutant Vaccinium berries show down-regulation of MYBPA1-type R2R3 MYB regulatory factor.

MYBPA1-type R2R3 MYB transcription factor shows down-regulation in white mutant berries of Vaccinium uliginosum deficient in anthocyanins but not proanthocyanidins suggesting a role in the regulation of anthocyanin biosynthesis. Berries of the genus Vaccinium are among the best natural sources of flavonoids. In this study, the expression of structural and regulatory flavonoid biosynthetic genes and the accumulation of flavonoids in white mutant and blue-colored wild-type bog bilberry (V. uliginosum) fruits were measured at different stages of berry development. In contrast to high contents of anthocyanins in ripe blue-colored berries, only traces were detected by HPLC-ESI-MS in ripe white mutant berries. However, similar profile and high levels of flavonol glycosides and proanthocyanidins were quantified in both ripe white and ripe wild-type berries. Analysis with qRT-PCR showed strong down-regulation of structural genes chalcone synthase (VuCHS), dihydroflavonol 4-reductase (VuDFR) and anthocyanidin synthase (VuANS) as well as MYBPA1-type transcription factor VuMYBPA1 in white berries during ripening compared to wild-type berries. The profiles of transcript accumulation of chalcone isomerase (VuCHI), anthocyanidin reductase (VuANR), leucoanthocyanidin reductase (VuLAR) and flavonoid 3'5' hydroxylase (VuF3'5'H) were more similar between the white and the wild-type berries during fruit development, while expression of UDP-glucose: flavonoid 3-O-glucosyltransferase (VuUFGT) showed similar trend but fourfold lower level in white mutant. VuMYBPA1, the R2R3 MYB family member, is a homologue of VmMYB2 of V. myrtillus and VcMYBPA1 of V. corymbosum and belongs to MYBPA1-type MYB family which members are shown in some species to be related with proanthocyanidin biosynthesis in fruits. Our results combined with earlier data of the role of VmMYB2 in white mutant berries of V. myrtillus suggest that the regulation of anthocyanin biosynthesis in Vaccinium species could differ from other species studied.

Expression of stable reference genes and SPINDLY gene in response to gibberellic acid application at different stages of grapevine development

Gibberellic acid (GA3) is widely used at different stages of berry development, and to understand the molecular mechanism of its action requires identification of stable reference genes. We sprayed grapevine (Vitis vinifera L.) cv. Thompson Seedless with GA3 at rachis stage for rachis elongation, at flower cluster stage for flower thinning, and at 3-4 mm berry stage for berry elongation. Tissue samples were collected at different time points after GA3 application. The expression of 10 candidate reference genes was analyzed using 4 different algorithms to assess their suitability for real time-PCR data normalization. Based on the overall ranking, PP2A, Sutra, and SAND were identified as the most stably expressed genes across all samples. With regard to different stages, tubulin, EF1α, and UBC were the most stable genes during rachis elongation; PP2A, SAND, and Sutra were the most suitable at the flower cluster and berry stages. The expression of GA signaling gene SPINDLY (VvSpy) was analyzed to validate the stable reference genes. After the GA3 application, the expression of VvSpy was reduced at the rachis stage but did not change at the flower cluster and berry stages. The expression profile of VvSpy was comparable when two or three reference genes were used for data normalization.

Use of diffusion magnetic resonance imaging to correlate the developmental changes in grape berry tissue structure with water diffusion patterns.

BackgroundOver the course of grape berry development, the tissues of the berry undergo numerous morphological transformations in response to processes such as water and solute accumulation and cell division, growth and senescence. These transformations are expected to produce changes to the diffusion of water through these tissues detectable using diffusion magnetic resonance imaging (MRI). To assess this non-invasive technique diffusion was examined over the course of grape berry development, and in plant tissues with contrasting oil content.ResultsIn this study, the fruit of Vitis vinfera L. cv. Semillon at seven different stages of berry development, from four weeks post-anthesis to over-ripe, were imaged using diffusion tensor and transverse relaxation MRI acquisition protocols. Variations in diffusive motion between these stages of development were then linked to known events in the morphological development of the grape berry. Within the inner mesocarp of the berry, preferential directions of diffusion became increasingly apparent as immature berries increased in size and then declined as berries progressed through the ripening and senescence phases. Transverse relaxation images showed radial striation patterns throughout the sub-tissue, initiating at the septum and vascular systems located at the centre of the berry, and terminating at the boundary between the inner and outer mesocarp. This study confirms that these radial patterns are due to bands of cells of alternating width that extend across the inner mesocarp. Preferential directions of diffusion were also noted in young grape seed nucelli prior to their dehydration. These observations point towards a strong association between patterns of diffusion within grape berries and the underlying tissue structures across berry development. A diffusion tensor image of a post-harvest olive demonstrated that the technique is applicable to tissues with high oil content.ConclusionThis study demonstrates that diffusion MRI is a powerful and information rich technique for probing the internal microstructure of plant tissues. It was shown that macroscopic diffusion anisotropy patterns correlate with the microstructure of the major pericarp tissues of cv. Semillon grape berries, and that changes in grape berry tissue structure during berry development can be observed.

Application of exogenous 24-epibrassinolide enhances proanthocyanidin biosynthesis in Vitis vinifera ‘Cabernet Sauvignon’ berry skin

‘Cabernet Sauvignon’ (Vitis vinifera L.) grape berries were treated with 0.4 mg/l 24-epibrassinolide applied once at fruit set (‘pea-sized berry’ phenological stage) (EBR-T1) or the same concentration EBR applied twice at fruit set and 14 days before veraison (EBR-T2). Berries sprayed with deionized water served as the control. The contents of proanthocyanidins (PAs) in the berry skin and seed, and the expression patterns of structural genes (VvLAR1, VvLAR2, VvANR, and VvANS) and transcription regulator genes (VvMYB5a, VvMYB5b, and VvMYBPA1) of PAs in the berry skin were measured. At berry maturity, total tannins in the skin of EBR-T1- and EBR-T2-treated berries were significant higher than those in control. Monomeric and oligomeric flavan-3-ols showed different levels of promotion by 24-epibrassinolide during berry development. The mRNA levels of the structural genes VvLAR1, VvLAR2, and VvANS and the transcription regulator gene VvMYBPA1 were affected significantly by 24-epibrassinolide treatment, but the effects varied at different stages of berry development. Most of the targets measured showed no significant difference between the EBR-T1 and EBR-T2 treatments. Thus, in general, application of 24-epibrassinolide enhanced PAs biosynthesis in the berry skin.

Sunlight exclusion from Muscat grape alters volatile profiles during berry development

The effects of sunlight exclusion on the volatile profiles of grapes during different stages of berry development were investigated by placing clusters of grapes in special boxes. Terpenes and aldehydes were the main volatile compounds in the ripe ‘Jingxiangyu’ berries. Sunlight exclusion was found to change volatile profiles at any stage. Sunlight exclusion from berries significantly inhibited the synthesis and accumulation of terpenes, which contribute to the characteristic aroma of Muscat grapes. However, sunlight exclusion during berry formation and veraison promoted the accumulation of aldehydes, alcohols, and ketones during the ripening stage. These results may provide important information regarding the metabolism of volatile compounds in grapes.

The Berries of Santalum album L. as a New Source of Cyanidin-3-Glucoside and Chemical Profiling during Different Stages of Berry Development

Changes during development of Santalum album L. berries were studied with respect to contents of pigment, carbohydrates, proteins, phenols, organic acids, colour and biomass. Cyanidin-3-glucoside (anthocyanin pigment) content increased rapidly from early (green) through intermediate (pink) to matured stage (black). Carbohydrates and proteins contents also increased during berry development. Phenols contents got reduced on maturation of the berries while total organic acids contents increased. Colour parameters such as L, b and chroma values decreased, whereas a value increased from green to pink stage, then decreased on ripening of the berries. Although berry size increased but seed weight did not change indicating biomass increase. From the present study, it is concluded that only the black (or matured) berries of S. album may be harvested for maximum yield of anthocyanin pigment.

Optimisation of an HPLC method for the simultaneous quantification of the major sugars and organic acids in grapevine berries

A high performance liquid chromatographic method was developed to profile major sugars and organic acids in grapevine berries. Sugars and organic acids in grapevine berries were extracted by chloroform/polyvinylpolypyrrolidone purification. The extracts were chromatographed on an Aminex HPX-87H ion-exchange HPLC column with 5mM sulphuric acid as mobile phase. Chromatography was visualised via a diode array detector combined with a refractive index detector. The analysis was calibrated using external standard calibration and a novel equation was used to calculate the concentrations of malic acid and fructose from unresolved separation. For the method to be utilised for analysing a large numbers of berry samples, each sample was directly injected after sample extraction and the extraction step was downscaled to allow the use of small amounts of sample material. The concentrations of sugars and organic acids in grapevine berry samples were normalised to the internal standard concentrations obtained after extraction of an internal standard mixture. The analysis method exhibits a good precision and a high analyte recovery from samples spiked with the standard mixture and is suitable for the profiling of major sugars and organic acids in grapevine berry samples at different stages of berry development. This is the first report on the combined profiling of the major sugars and organic acids in grapevine berries using milligram amounts of plant material with direct injection after sample extraction.

Distribution of major sugars, acids, and total phenols in juice of five grapevine (Vitis spp.) cultivars at different stages of berry development

The juices of five grapevine cultivars cultivated in a typical Mediterranean climate were analyzed for sugars, organic acids, and phenols at four distinct stages of berry development. When the unripe berries were almost in full size, the glucose and fructose contents, based on HPLC detection, ranged from 13.3 to 30.7 g L-1 and from 8.3 to 23.7 g L-1 for ‘Muscat of Alexandria’ and ‘Muscat of Hamburg’, respectively. At this stage, tartaric acid concentration was between 10.3 (‘Italia’) and 12.3 g L-1 (‘Muscat of Alexandria’), while the level of total phenols was low. Up to véraison, there were slight reductions in organic acids, while sugar content increased slightly. However, dramatic changes in all genotypes were apparent after véraison. Slight reductions were determined in the glucose and fructose levels of ‘Italia’ prior to final analysis, possibly indicating this cultivar’s sensitivity to late harvest. In the final analysis, glucose and fructose content varied from 86.4 (‘Italia’) to 107.0 g L-1 (‘Muscat of Hamburg’), and from 73.1 (‘Italia’) to 94.1 g L-1 (‘Alphonse Lavallée’), respectively. Tartaric acid content of ripe berries was between 3.8 (‘Alphonse Lavallée’) and 5.2 g L-1 (‘Isabella’) with a mean value of 4.6 g L-1, and phenol content of mature berries ranged from 2253 to 2847 mg L-1. This study provides valuable information for further understanding the sugar, acid and total phenol changes that occur in some grape cultivars during berry maturation. Therefore, these results will be useful for future research on the biochemistry of the grape berry.

Amino Acid Profile of ‘Thompson Seedless’ Grapes Grafted on Different Rootstocks at Various Stages of Berry Development

The concentrations of amino acids from ‘Thompson Seedless’ grapes grafted on different rootstocks were estimated at different stages of berry development using high performance liquid chromatography with tandem mass spectrometry analysis. Significant differences in the concentrations of individual amino acids and total amino acids were observed among different rootstocks. The pattern in accumulation of a particular amino acid was the same on all the rootstocks, but the stage at which it reached the highest level differed with the rootstock. Proline content was highest after veraison on most of rootstocks and its concentration remained same until harvest, while that of arginine decreased after ripening until harvesting.

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.

ブドウ‘デラウェア’における光合成産物の転流と分配

Distribution of photosynthates from leaves into different plant parts was studied in potted 2-year-old ‘Delaware’ grape which were exposed to 14CO2 at different stages of berry development. In the first experiment, shoots, trunks, roots, berries and leaves were sampled 6, 24 and 72 hours after 14CO2 feeding and the 14C activities in the ethanol soluble and insoluble fractions were measured. In the second experiment, each ethanol soluble fraction of shoots, berries and leaves being sampled 6 hours after 14CO2 feeding was separated into individual compounds by paper and column chromatography, and the 14C activities were then estimated. The results are summarized as follow1. 14C in the ethanol soluble and insoluble fractions in leaves decreased with time after 14CO2 feeding. The 14C labelled photosynthates translocated from leaves into shoots, trunks and roots increased in the ethanol insoluble fraction 24 and 72 hours after feeding, but did not increase in the ethanol soluble fraction.2. The amount of 14C translocated into berries increased at Stage I and III, and appeared mostly in the ethanol soluble fraction in both stages.3. In seeds, more 14C was found in the ethanol insoluble fraction than in the ethanol soluble fraction, and the incorporation ratio increased in the course of berry development from Stage I to Stage II.4. In leaves and shoots, the 14C incorporated into the sugar fraction was mainly found in sucrose, glucose and fructose, and that in the organic acid fraction was mainly in malic acid and tartaric acid. In berries, the distribution of 14C into sugar and organic acid fractions was similar to that in leaves and shoots, except for sucrose. However, the 14C distribution ratio varied at different stages of berry development.

Influence of Timing of Ethephon Application on Yield and Fruit Composition of Chenin Blanc Grapevines

Chenin blanc grapevines at Davis were treated with single applications of 750 ppm ethephon at nine different stages of berry development. The first treatment began at full bloom (>90% anthesis) with eight subsequent treatments sprayed at one week intervals following bloom. Results were compared with an unsprayed control. Overall yield, primary crop yield, and number of primary clusters were significantly reduced in vines treated with ethephon up to two weeks after bloom. Second crop yield and number of secondary clusters were reduced in all ethephon treatments. Ethephon applied at bloom and one week post-bloom significantly reduced °Brix and pH, but increased titratable acidity of fruit at harvest. Ethephon applied six and nine weeks post-bloom increased °Brix without altering titratable acidity or pH, relative to the control. Fruit potassium levels of vines treated with ethephon at bloom and one, two, three and seven weeks after bloom differed significantly from the control fruit when sampled in mid-August, but the effect was transitory with all the differences eliminated by early September.