Seyval Blanc Research Articles

Impact of cluster thinning and harvest date on berry volatile composition and sensory profile of <i>Vitis</i> sp. Seyval blanc and Vandal-Cliche

Northern conditions are challenging for grape and wine producers. To cope with these challenges, the use of early ripening interspecific hybrid Vitis sp., such as Seyval blanc and Vandal-Cliche, is often preferred to traditional V. vinifera. However, knowledge about cultural practices suitable for interspecific hybrid varieties are still scarce, especially regarding their impact on profiles of volatile compounds and the sensory perception of berries. In this study, the impact of cluster thinning and harvest date on grapevine physiology, must chemical composition and berry sensory attributes of Seyval blanc and Vandal-Cliche was investigated. Three crop loads (100 %, 70 % and 40 % crop) and three harvest dates corresponding to pre-maturity, maturity, and post-maturity were assessed in 2012 and 2013. Cluster thinning significantly decreased the yield of Vandal-Cliche, but not of Seyval blanc, for which it instead improved fruit set without affecting yield. The impact of cluster thinning on must chemical composition was limited for both cultivars, although some significant changes were observed, especially in the cool season of 2013. Clear variations during ripening, in terms of technological parameters and aroma characteristics, were observed depending on the cultivars and the seasons. In Seyval blanc, C6-alcohols and C13-norisoprenoids decreased during ripening, while C6-aldehydes and linalool increased. In Vandal-Cliche, berries from the first and the last sampling dates of the warm season of 2012 showed the highest levels of C13-norisoprenoids, whereas berries from the last sampling date in the cold season of 2013 showed the highest levels of terpenes, C13-norisoprenoids and ethyl esters. Despite its limited impact on fruit chemical composition, cluster thinning significantly impacted the sensory perception of Vandal-Cliche berries in both years. Cluster-thinned berries had softer skin, sweeter and less acidic pulp, and fruitier skin and pulp aroma. Skin softness allowed excellent discrimination of the maturity of both cultivars during the two study years, suggesting that this descriptor could be a suitable maturity marker for these interspecific hybrid varieties. In summary, cluster thinning proves beneficial for enhancing fruit set in Seyval Blanc in a northern climate; however, its influence on fruit quality is minimal for both cultivars.

Genetic analysis of grapevine root system architecture and loci associated gene networks.

Own-rooted grapevines and grapevine rootstocks are vegetatively propagated from cuttings and have an adventitious root system. Unraveling the genetic underpinnings of the adventitious root system architecture (RSA) is important for improving own-rooted and grafted grapevine sustainability for a changing climate. Grapevine RSA genetic analysis was conducted in an Vitis sp. 'VRS-F2' population. Nine root morphology, three total root system morphology, and two biomass traits that contribute to root anchorage and water and nutrient uptake were phenotyped. Quantitative trait loci (QTL) analysis was performed using a high density integrated GBS and rhAmpSeq genetic map. Thirty-one QTL were detected for eleven of the RSA traits (surface area, root volume, total root length, fresh weight, number of tips, forks or links, longest root and average root diameter, link length, and link surface area) revealing many small effects. Several QTL were colocated on chromosomes 1, 9, 13, 18, and 19. QTL with identical peak positions on chromosomes 1 or 13 were enriched for AP2-EREBP, AS2, C2C2-CO, HMG, and MYB transcription factors, and QTL on chromosomes 9 or 13 were enriched for the ALFIN-LIKE transcription factor and regulation of autophagy pathways. QTL modeling for individual root traits identified eight models explaining 13.2 to 31.8% of the phenotypic variation. 'Seyval blanc' was the grandparent contributing to the allele models that included a greater surface area, total root length, and branching (number of forks and links) traits promoting a greater root density. In contrast, V. riparia 'Manitoba 37' contributed the allele for greater average branch length (link length) and diameter, promoting a less dense elongated root system with thicker roots. LATERAL ORGAN BOUNDARY DOMAIN (LBD or AS2/LOB) and the PROTODERMAL FACTOR (PFD2 and ANL2) were identified as important candidate genes in the enriched pathways underlying the hotspots for grapevine adventitious RSA. The combined QTL hotspot and trait modeling identified transcription factors, cell cycle and circadian rhythm genes with a known role in root cell and epidermal layer differentiation, lateral root development and cortex thickness. These genes are candidates for tailoring grapevine root system texture, density and length in breeding programs.

Thiol precursors and amino acids profile of white interspecific hybrid <i>Vitis</i> varieties and impact of foliar urea and sulfur supplementation on the concentration of thiol precursors in <i>Vitis</i> sp. Vidal berries

Thiols are a group of highly potent aroma compounds found in many Vitis vinifera wines. In berries, thiols occur as precursors formed from a thiol attached to an amino moiety (e.g., cysteine and glutathione). Foliar sulfur and urea supplementation has been found to increase thiol precursors in V. vinifera berries. However, such data are still scarce for interspecific hybrid Vitis varieties, despite a growing interest in these cultivars. In this study, eight thiol precursors, 21 amino acids and glutathione (GSH) of seven white hybrid Vitis varieties collected in Quebec, Canada, were quantified by liquid chromatography with tandem mass spectrometry. Then, the impact of foliar sulfur and urea supplementation on thiol precursors of fully mature berries was tested on the Vitis sp. Vidal, using a complete randomised block design. Among the analysed thiol precursors, only the precursors of 3-mercaptohexan-1-ol (3MH) were detected, with glutathione-3MH (20-711 μg/kg berry fresh weight) as the main precursor in most studied varieties. Vidal samples had the highest concentrations of glutathione-3MH (313 μg/kg berry fresh weight) and GSH (17 mg/L in juice), but a large variability was found among the biological replicates. The amino acids proline, arginine, glutamine and alanine were the main amino acids found in Vidal, Frontenac blanc, Seyval blanc and Saint-Pepin respectively. Correlation analysis showed no significant relationship between thiol precursor and glutathione/amino acid content in berries. Foliar urea and sulfur supplementation had no impact on thiol precursor concentration in Vidal. However, a trend in a higher content of thiol precursors in berries treated with urea and sulfur compared to the control was observed on one of the two experimental sites.

New Isolated Autochthonous Strains of S. cerevisiae for Fermentation of Two Grape Varieties Grown in Poland

Many commercial strains of the Saccharomyces cerevisiae species are used around the world in the wine industry, while the use of native yeast strains is highly recommended for their role in shaping specific, terroir-associated wine characteristics. In recent years, in Poland, an increase in the number of registered vineyards has been observed, and Polish wines are becoming more recognizable among consumers. In the fermentation process, apart from ethyl alcohol, numerous microbial metabolites are formed. These compounds shape the wine bouquet or become precursors for the creation of new products that affect the sensory characteristics and quality of the wine. The aim of this work was to study the effect of the grapevine varieties and newly isolated native S. cerevisiae yeast strains on the content of selected wine fermentation metabolites. Two vine varieties—Regent and Seyval blanc were used. A total of 16 different yeast strains of the S. cerevisiae species were used for fermentation: nine newly isolated from vine fruit and seven commercial cultures. The obtained wines differed in terms of the content of analyzed oenological characteristics and the differences depended both on the raw material (vine variety) as well as the source of isolation and origin of the yeast strain used (commercial vs. native). Generally, red wines characterized a higher content of tested analytes than white wines, regardless of the yeast strain used. The red wines are produced with the use of native yeast strains characterized by higher content of amyl alcohols and esters.

Berry Anthocyanin, Acid, and Volatile Trait Analyses in a Grapevine-Interspecific F2 Population Using an Integrated GBS and rhAmpSeq Genetic Map.

Increased map density and transferability of markers are essential for the genetic analysis of fruit quality and stress tolerance in interspecific grapevine populations. We used 1449 GBS and 2000 rhAmpSeq markers to develop a dense map for an interspecific F2 population (VRS-F2) that was derived by selfing a single F1 from a Vitis riparia x ‘Seyval blanc’ cross. The resultant map contained 2519 markers spanning 1131.3 cM and was highly collinear with the Vitis vinifera ‘PN40024’ genome. Quantitative trait loci (QTL) for berry skin color and flower type were used to validate the map. Four rhAmpSeq transferable markers were identified that can be used in pairs (one pistillate and one hermaphroditic) to predict pistillate and hermaphrodite flower type with ≥99.7% accuracy. Total and individual anthocyanin diglucoside QTL mapped to chromosome 9 near a 5-O-GLUCOSYLTRANSFERASE candidate gene. Malic acid QTL were observed on chromosome 1 and 6 with two MALATE DEHYRDROGENASE CYTOPLASMIC 1 and ALUMINUM-ACTIVATED MALATE TRANSPORTER 2-LIKE (ALMT) candidate genes, respectively. Modeling malic acid identified a potential QTL on chromosome 8 with peak position in proximity of another ALMT. A first-ever reported QTL for the grassy smelling volatile (E)-2-hexenal was found on chromosome 2 with a PHOSPHOLIPID HYDROPEROXIDE GLUTATHIONE PEROXIDASE candidate gene near peak markers.

Genetic analysis of loose cluster architecture in grapevine

Loose cluster architecture is a well known trait supporting Botrytis resilience by permitting a faster drying of bunches. Furthermore, a loose bunch enables a better application of fungicides into the cluster. The analysis of 150 F1 plants of the superior breeding line GF.GA-47-42 (‘Bacchus' x ‘Seyval blanc') crossed with ‘Villard blanc' segregating for compactness of the cluster was used for QTL analysis. Plenty of QTL were identified reproducibly for two years, QTLs stable over three growing seasons were identified for rachis length, peduncle length, and pedicel length. In a second approach ‘Pinot noir' clones showing variation for cluster architecture were analyzed for differential gene expression. Grown in three different German viticultural areas, loose versus compact clustered ‘Pinot noir' clones showed in gene expression experiments a candidate gene expressed fivefold higher in loosely clustered clones between stages BBCH57 and BBCH71.

Breeding of fungal resistant varieties derived from Grüner Veltliner by chromosomal selection

Traditional cultivar Gruner Veltliner is the most appreciated vine in Austrian viticulture. Due to organic growing the demand for mildew resistance within the same wine profile has increased. Cross breeding can provide such new genotypes which combine traits from different sources by parenthood. Linkage of traits with chromosomes or markers allows to predict some aspects of the phenotype. Equipped with chromosomal assisted selection the development of new varieties could be much easier and faster. On the base of two segregating populations derived from crosses of Gruner Veltliner with Malverina and Seyval blanc we could define correlation of chromosomes with some traits. Mainly ampelographic descriptors and resistance against mildew could be aligned. As a quality parameter of the wine Rotundone analyses were performed and could be attributed to chromosome 5 and 9. Selection supported by the composition of the parental chromosomes enables breeding with some arguments of design. The limits for free choice were the availability of sufficient different genotypes with a broad spectrum of chromosomal combinations. Recently released descendent cultivar Donauveltliner was selected due to the high rate of Traminer alleles.

Influence of cluster exposure on fruit composition and wine quality of seyval blanc grapes

Experiments were conducted in 1981 and 1982 to investigate the influence of duster exposure on fruit composition, wine quality, and incidence of bunch rot ( Botrytis cinerea PERS.) of the French-American hybrid grape cultivar Seyval blanc. Berry sampling from 4 exposure categories (western exposure, eastern exposure, partial shade, and full shade) indicated highest °Brix, pH and tartrate, and lowest titratable acidity (TA) and malate in the exposed fruit post veraison. Total acidity and malate were highest in exposed fruit between fruit set and veraison. Exposure of the fruit also reduced the incidence of bunch rot during the 1981 season. Wine quality differences were small and not statistically significant, although wines vinted from exposed fruit tended to score higher. Canopy management practices that optimize fruit exposure would be helpful in maximization of fruit and wine quality.

Characterization of the feeding behavior of three Erythroneura species on grapevine by histological and DC‐electrical penetration graph techniques

AbstractFeeding behavior of three leafhopper species – Erythroneura vitis (Harris), Erythroneura ziczac (Walsh), and Erythroneura elegantula (Say) (Hemiptera: Cicadellidae) – reared on grapevine, Vitis vinifera L. cv. ‘Seyval blanc’ (Vitaceae), was investigated using histological techniques and DC‐electrical penetration graphs (DC‐EPG). Histological studies revealed that the Erythroneura species induced white stipples on the leaves and that these leafhoppers produced thin salivary sheaths in grapevine leaf tissues. The DC‐EPG system allowed the characterization of five waveforms associated with stylet penetration and feeding in leaf tissues. These waveforms were characteristic of feeding phases corresponding to epidermis penetration pathway, salivation, and ingestion. We calculated 28 parameters (e.g., number of probes, duration of phases, and time spent in the various tissues) to describe and compare the feeding behavior of the Erythroneura species. We conclude that the three Erythroneura species are mainly mesophyll feeders but may probably also feed in other tissues such as xylem.

Evaluation of Northern Grape Hybrid Cultivars for Their Susceptibility to Anthracnose Caused by Elsinoe ampelina

Use of winter-hardy grape cultivars has enabled expansion of wine grape production in the province of Quebec, Canada, but some of the cultivars have been reported as susceptible to grape anthracnose, a serious disease. The disease causes grape leaves and berries to dry up and drop prematurely, resulting in poor or no yield and, in cold climates, reduced winter survival. On susceptible cultivars, anthracnose management is costly, making grape production unprofitable. Therefore, cold climate grape cultivars were evaluated for their susceptibility to leaf infection by E. ampelina. Plants were grown from dormant cuttings and on each plant the youngest three leaves were tagged and inoculated with a conidial suspension of E. ampelina (1 × 106 spores per ml). Immediately after inoculation, plants were maintained under high humidity conditions at 24 ± 2°C for 72 h. The number of lesions per leaf was determined 14 days after inoculation. Cluster analysis was used to group the cultivars based on their susceptibility. The cultivars were classified as: (i) resistant or slightly susceptible – DM 8521-1, ES 10-18-30, St-Pépin, Sabrevois, Vidal banc, Baltica, Frontenac gris, Ste-Croix, Somerset, Frontenac, Seyval blanc; (ii) susceptible – Muscat de Swenson, Geisenheim, La Crescent, Frontenac blanc, Louise Swanson, Delisle; and (iii) highly susceptible – Swenson White, Vandal Cliche, Traminette, and Marquette. Knowledge of the susceptibility of grape cultivars to anthracnose will help growers to make prudent cultivar choices when new vineyards are established. Accepted for publication 31 May 2011. Published 5 August 2011.

Effects of Low-growing Perennial Ornamental Groundcovers on the Growth and Fruiting of `Seyval blanc' Grapevines

Greenhouse and field-grown `Seyval blanc' grapevines (Vitis sp.) were grown with low-growing, shallow-rooted, mat-forming, ornamental perennial groundcovers, and the effect of the groundcovers on the vegetative and fruiting growth of the grapevines was evaluated. The groundcovers used in this experiment were `Kentucky-31' tall fescue (Festuca arundinacea); white mazus (Mazus japoonicus albus); english pennyroyal (Mentha pulegium); dwarf creeping thyme (Thymus serpyllum minus); strawberry clover (Trifolium fragiferum); `Heavenly Blue' veronica (Veronica prostrata `Heavenly Blue'); and a companion grass mixture of 75% perennial ryegrass (Lolium perenne) and 25% red fescue (Festuca rubra). A control treatment grown without any groundcover was also used in both the greenhouse and field experiments. All of the groundcovers reduced `Seyval blanc' total shoot length from 22% to 85% in the vineyard. Cluster size was reduced in the field from 7% to 68% by the groundcovers compared to the herbicide control treatment, and from 9% to 66% in the greenhouse experiment, but none of the groundcovers in either the greenhouse or field experiments affected the pH, total acidity, or soluble solids concentrations of the `Seyval blanc' juice. English pennyroyal was the only groundcover that reduced in the leaf area of the grapevine. Single-leaf photosynthesis of the `Seyval blanc' grapevines in the field experiment was reduced by all groundcovers except mazus and creeping thyme. Water infiltration rates were 10 to 50 times higher in the groundcovers compared to the bare soil of the herbicide control treatment. Weed growth in the field caused reduction in shoot length similar to the most competitive groundcovers. Weed growth was reduced in the early season by the english pennyroyal and companion grass, and in the late season by all groundcovers. The reduction in growth of the grapevines caused by groundcovers in the greenhouse was a reasonable screen for the affect of groundcovers in the field. The mazus treatment was the only groundcover in our experiments that coupled fast growth with low competitive ability.

Chemical Bloom Thinning Hybrid Grape Cultivars

Abstract Caustic chemicals (Endothall, Wilthin and ammonium thiosulfate) were applied at bloom to French-American hybrid grape cultivars (‘Seyval blanc’, ‘Vidal blanc’, and ‘Chambourcin’) to evaluate their potential as chemical thinners. The chemicals caused phytotoxicity to leaves and clusters resulting in brown, dead spots on leaves and brown areas of the clusters. Injury symptoms increased as concentration of Endothall increased. ‘Vidal blanc’ was the most sensitive cultivar to Endothall and ‘Chambourcin’ was the most sensitive to ammonium thiosulfate (ATS). Hand cluster thinning at bloom consistently increased cluster weight, berry number per cluster, juice soluble solids and pH and decreased cluster number and yield of all cultivars with the exception that yield of ‘Seyval blanc’ was reduced only one year. Generally as concentration of Endothall increased, thinning increased. Endothall at 1.92 ml-L-1 caused reductions in yield and increases in juice soluble solids and pH that were very similar to han...

Endothall Thins Grapevines

Abstract The purpose of this study was to determine if Endothall could reliably thin ‘Concord’, ‘Chancellor’, and ‘Seyval blanc’ grapevines while improving fruit composition and maintaining acceptable levels of phytotoxicity. Endothall was applied to runoff at 1.9 and 3.8 ml-L-1 and was targeted at clusters or whole vines. Applications were made either at 75% bloom for ‘Chancellor’ and ‘Seyval’ or 25%, 75%, and 100% bloom for ‘Concord’. Vines were rated for phytotoxicity. Yields and fruit composition were recorded at harvest. All cultivars experienced leaf phytotoxicity relative to Endothall concentration. However, the amount of leaf area affected did not cause any reductions in fruit soluble solids, such that all Endothall applications resulted in either the same or greater fruit soluble solids than the untreated vines. For ‘Concord’, thinning was possible over a 3 — to 4-day period ranging from 25% to 100% bloom, with 75% bloom being the most reliable time for thinning. Endothall increased fruit soluble...

Transgenic plants of Vitis vinifera cv. Seyval blanc

Leaf discs of grapevine cv. Seyval blanc originating from in vitro cultures were transformed with Agrobacterium tumefaciens strain LBA 4404 harbouring the vector pGJ42 carrying genes for chitinase and RIP (ribosome-inactivating protein) in an attempt to improve fungal resistance. The gene for neomycin phosphotransferase II (nptII) was used as the selectable marker gene. The explants were cocultivated for 2 days with recombinant Agrobacteria and then submitted to selection on NN69 medium containing 100 mg/l kanamycin. Successful regeneration and conversion of transgenic plantlets were obtained. Stable integration of foreign DNA was confirmed by PCR and Southern blot analyses, and protein expression was detected by Western blot. The regenerated transgenic plants were adapted to the greenhouse and showed no evidence of phenotypical alterations. The foreign genes introduced into the transformed plants did not effect the expected improvement in fungal disease resistance under field conditions for the major pests Uncinula necator and Plasmopara viticola.

The Effects of Different Cultural and Environmental Factors on Grapevine Growth, Winter Hardiness and Performance, in Three Locations, in Canada

Abstract Twenty grapevine genotype of diverse hybrid origin (‘Chancellor’, ‘Delisle’, ‘ES-6-12-28’, ‘ES-4-7-25’, ‘GR-7’ ‘Hibernal’, ‘Sabrevois’, ‘Kay Gray’, ‘Lucie Kuhlmann’, ‘Michurinetz’, ‘Okanagan Riesling’, ‘Prairie Star’, ‘St. Croix’, ‘St. Pepin’, ‘Seyval noir’, ‘Seyval blanc’, ‘SV-18-307’, ‘Vandal-Cliche’ and ‘Vidalblanc’)andonevmf/era (’Siegerrebe’) were evaluated under different winter protection methods where twelve hardy and semi-hardy genotypes received 3 treatments: seven tender genotypes received one treatment and only one tender genotype received 2 treatments [vines without protection: (Ml)]; pinning half of the canes to the ground allowing for natural snow cover protection and the remaining canes left attached to the trellis wires without protection (M2); vine removed from the trellis, laid down and covered with geotextile fabric (M3) or soil (M4) at three locations in Quebec (Canada) differing in soil type and microclimate conditions. The effects of these methods on annual production, winter resistance and vegetative growth were measured. Total yield for all genotypes at Frelighsburg were 3 and 4 times higher than at L'Orpailleur (Dunham) and Dietrich-Jooss (Iberville) commercial vineyards, respectively. For protection system Ml and M2, the highest yields were recorded for ‘Vandal-Cliche’ and ‘St. Croix’ followed by ‘ES-4-7-25’ and ‘St. Pepin’. The M3 treatment was the most effective protection for some semi-hardy genotypes. Under M3 protection average yield of semi-hardy genotypes remained higher (6 and 4 kg) than that of the hardy genotypes (3 and 1.7 kg) at L'Orpailleur and Dietrich-Jooss (2000), respectively. ‘Seyvalnoir’, ‘Seyvalblanc’, ‘Chancellor’, ‘Vandal-Cliche’, and ‘ES-4-7-25’ exceeded 20 kg under M3 treatment. M4 protection for ‘Seyval blanc’ was not effective resulting in decreased yield, vigour and increased mortality. Higher bud survival levels were observed at Frelighsburg for hardy genotypes such as ‘Sabrevois’, ‘St. Croix’, ‘Kay Gray’, ‘Vandal-Cliche’, ‘St. Pepin’ and ‘Michurinetz’ under all protection treatments. In commercial vineyards, greater than 50% bud mortality was observed for semi-hardy genotypes ‘ES-6-12-28’, ‘GR-7’ and ‘Lucie Kuhlman’, with even higher mortality in tender genotypes ‘Siegerrebe’, ‘Vidal blanc’ and ‘SV-18-307’. The highest vigour was achieved in hardy and moderately hardy cultivars while the tender cultivars were less vigorous at all three sites and over both years. Site location was the most important factor affecting vine yield and mortality, with the best performances being recorded at Frelighsburg. This is assured due to the site in Frelighsburg having a slight south slope very well drained sandy soil, and excellent snow accumulation.

PHOTOSYNTHETIC INHIBITION OF 'SEYVAL BLANC' GRAPEVINES WITH TERBACIL

PHOTOSYNTHETIC INHIBITION OF 'SEYVAL BLANC' GRAPEVINES WITH TERBACIL

Evaluation of the productivity of the hybrid vine Seyval blanc in function of several types of protection against frost in Quebec

<p style="text-align: justify;">In Quebec, winter frost is one of the determining factors influencing vine survival and yield. To evaluate the quality of the different types of winter protection, ground temperature data under different covers (ground knolls, leaf mounds, carried over snow and natural snow) and ambient air temperatures were recorded. Results show that the Seyval blanc, if not protected against winter frost, can sustain quite serious damages when the air temperature reaches -30 °C. Ridging, leaf covering and the natural snow cover as well as carried over snow have a positive effect on ground temperatures, since over the site without protection, frost penetrated down to a depth of 50 cm. However, it seems that the root System did not sustain significant damages from the ground frost since regrowth occurred in the Spring. Because of its direct exposure to radiation and surface climatic conditions, bare soil warms up more quickly in the Spring compared to the other sites benefiting from protection. Results also indicate that the mortality rate of the vine stock fruit buds without protection is nearly 100 % compared to the protected vine stocks with a fruit bud mortality rate varying from 22.5 to 35.8 %. The protected vine stocks, regardless of the type of protection used, had satislactory yields from 7.2 t/ha to 24.4 t/ha. On the other hand, the raisin yield of the vine stocks without any winter protection is null. The best raisin yields were obtained over sites where vine stocks were protected by ridging (40 cm of earth), while the vine stocks protected by leaf covering showed an average yield. We also observed that when vine stock leaf covering is coupled with lodged vine shoots, raisin yields are higher than when the vine shoots are erect. However, in both cases, potential yield per hectare is satisfactory. Hence, the lodging of vine shoots becomes a useless operation. The vine stocks protected by natural snow as well as by leaf covering (30 cm + carried over snow and lodged vine shoots) gave the fruit with the highest sugar content. Snow is also an excellent insulator because a 37 cm high snow cover permitted the survival of the vine stocks protected by snow even when the temperature reached -30 °C. The only problem still posing a threat is snow cover variability during the winter season. A reduced snow cover, coupled with temperature conditions under the threshold of tolerance of the vine to cold, could not insure satisfactory protection ol the fruit buds.</p>

Transient expression of <em>uid</em>A gene in grapevine protoplasts after PEG-mediated transformation

<p style="text-align: justify;">Leaf protoplasts, isolated from <em>Vitis vinifera</em> «Sakasly» and «Muscat d’Alexandrie» and protoplasts from embryogenic tissue of <em>Vitis</em> sp. «Seyval blanc» were incubated in the presence of PEG in a transformation solution containing the plasmid pBI426 which carries the β-glucuronidase (<em>gus</em>) and the neomycin phosphotransferase II (<em>npt</em>II) genes. The treated protoplasts were cultivated in CPW13 medium without kanamycin selection. 48h after the PEG transformation, transient expression of gus gene was detected histochemically and fluorimetrically in the protoplast cultures.</p>

Influence of Irradiance and Period of Exposure on Fruit Set of French-American Hybrid Grapes

Vines of container grown `DeChaunac', `Vidal blanc', `Seyval blanc' and `Chambourcin' grapes were subjected to 5 days of 80% shade at prebloom, bloom or 2 and 4 weeks after bloom. Fruit set, cluster weight, berries per cluster and juice components [soluble solids concentration (SSC), pH and titratable acidity] of `DeChaunac' and `Vidal blanc' were not affected by a short period of intensive shade. `Chambourcin' was sensitive to a shade period near the time of bloom for most of the aforementioned factors, while `Seyval blanc' was intermediate in sensitivity. Shot (green, hard, and undersized) berries of `Chambourcin' and `Seyval blanc' were increased by a 5-day period of shade 2 or 4 weeks after bloom. In a second study, container-grown `Chambourcin' on 3309C (V. riparia × V. rupestris) with one or two clusters and `Vidal blanc' with one cluster were subjected to the following light regimes beginning at bloom for 5 weeks: supplemental light, ambient greenhouse light and 30%, 50% or 80% shade. Yield, fruit set, specific leaf weight (leaf dry weight/leaf area), saturation index, and total leaf chlorophyll increased linearly with increasing irradiance. `Chambourcin' juice pH, SSC, leaf chlorophyll a/b ratio, cluster color development and hue angle decreased as irradiance increased, likely related to crop reduction. Responses in `Vidal blanc' followed similar trends, but differences were not as great. Results demonstrate that light is an important determining factor in fruit set of French-American hybrid grapes and fruit set of some cultivars are sensitive to short periods of intense shade.

Root Pruning Has Little Effect on Seyval, Catawba or Concord Grapevines

Abstract Mature grapevines were mechanically root pruned to a depth of 40-45 cm on two sides, 40-50 cm from the trunk. Root pruning 'Seyval blanc’ and ‘Catawba’ (Vitis sp.) at bloom and/or veraison for three years had little effect on the various components of yield or juice composition. Pruning time of ‘Catawba’ was reduced by root pruning. Root pruning vigorous ‘Concord’ vines at bloom for four years resulted in a reduction in weight of cane prunings and pruning time in one of four years. Yield/vine was reduced two of the four years due to a reduction in cluster weight. Increasing levels of soil applied nitrogen to a maximum of 134.4 kg/ha had no effect on growth or cropping of ‘Concord’. Root pruning did not control vegetative growth or improve juice composition of grapes.