Fruit ripening in Vitis vinifera L.: possible relation of veraison to turgor and berry softening

Background and Aims:  Vitis vinifera L. berries exhibit dynamic changes in water relations during development, but the possible connections between water relations, particularly cell turgor pressure ( P ), and ripening have received little attention, and the water relations have been studied by mostly indirect methods.
Methods and Results:  The cell pressure probe was utilized to examine directly the in situ P of cells in the mesocarp. Mesocarp cell P demonstrated a consistent pattern of a high value early in development, followed by a decrease to less than 1.0 bar that was maintained during ripening. Sugar accumulation did not increase significantly until P had declined to less than 1.0 bar. Fruit 'elasticity' was used to evaluate fruit firmness during development. Fruit elasticity changed dynamically and synchronously with P . When growth was prevented with plastic boxes, the decline in cell P was delayed over 14 days, and the onset of skin colour and sugar accumulation was similarly delayed.
Conclusions:  The results show that when the decrease in P was delayed, the onset of ripening was delayed, and, therefore, are consistent with a central role of P in the onset of ripening.
Significance of the Study:  This study showed that boxing preveraison berries similarly delayed P decrease and colour increase in Cabernet Sauvignon berries. Thus, this system may be useful to study the relationship between P and gene expression in developing berries.     

Observations on the morphology and development of star flowers of Vitis vinifera L. cvs Chardonnay and Shiraz

Background and Aims: Following our original discovery of star flowers on grapevines in Australia, further variants of the star flower phenotype have been discovered on other varieties in South Australia. The objective of this report was to describe star flowers on Vitis vinifera L. cvs Chardonnay and Shiraz. Methods and Results: Field and microscopic observations revealed that star flowers on both varieties opened precociously; there was neither pollen nor pollen tubes on the stigmas of the star flowers, and both Chardonnay and Shiraz star flowers contained aberrant ovules. The Chardonnay vines with star flowers produced bunches with an abundance of seedless berries; however, star flowers on Shiraz vines did not develop into berries. Conclusions: The inability of the Shiraz star flowers to develop into berries suggests that either there are two different mutations affecting these two varieties, or else the difference lies in their contrasting parthenocarpic tendencies. Significance of the Study: The star flower variants described here and previously may be the result of deviations to the normal molecular pathway for flower development in Vitis species. The identification of star flowers on numerous varieties and in several different regions suggests that the occurrence of star flowers may be more widespread than previously realised, and the association of star flowers with the production of seedless berries and poor fruitset suggests that star flowers may also play a significant role in the problem of poor fruitset.     

Comparison of major volatile compounds from Riesling and Cabernet Sauvignon grapes (Vitis vinifera L.) from fruitset to harvest

Background and Aims: Research on concentration changes of volatile compounds during grape physiological development has focused on the period from veraison to harvest. This study compared the developmental changes in the major volatile compounds released after the crushing of Riesling and Cabernet Sauvignon grapes sampled from fruitset to harvest during the 2007–2008 season. Methods and Results: Volatile compounds were extracted from the headspace of crushed Riesling and Cabernet Sauvignon grapes sampled throughout berry development using solid-phase microextraction and analysed by gas chromatography–mass spectrometry. A multivariate statistical approach coupled with analysis of variance was applied to compare the developmental changes in volatile compounds for the two cultivars. In both cultivars, E-2-hexenal was the most abundant volatile compound, and it showed a significant increase in concentration after veraison. Benzene derivatives discriminated ripe Cabernet Sauvignon grapes, whereas monoterpenes and sesquiterpenes discriminated both cultivars pre-veraison with a broader range of terpenes observed in the Cabernet Sauvignon samples compared with the Riesling samples. At veraison, terpene production in both varieties was low, but Riesling grapes produced some terpenes (geraniol and α-muurolene) post-veraison. Generally, esters and aldehydes were the major class of compounds from Riesling grapes, while Cabernet Sauvignon showed a greater tendency to form alcohols. Conclusions: Both Riesling and Cabernet Sauvignon grapes had a more complex volatile compound composition pre-veraison than post-veraison. This study suggests that some compounds that contribute to grape aroma may be produced pre-veraison, and not simply accumulate after veraison. Significance of the Study: Understanding the timing of volatile compound production and cultivar differences will guide viticulture researchers and growers in the optimisation of vineyard strategies to enhance grape aroma attributes that may, in turn, contribute to wine aroma.     

Weight loss from ripening berries of Shiraz grapevines (Vitis vinifera L. cv. Shiraz)

Environmental and phenological correlatives associated with the onset of weight loss during ripening in Vitis vinifera cv. Shiraz berries were examined. An irrigation experiment concerned with transient water deficit effects on berry growth over four consecutive seasons provided source data. Timing of maximum berry weight was more closely correlated with the number of days after flowering than with temperature summation. Prior to maximum berry weight, Brix was more closely correlated with days after flowering than with temperature summation, while the number of days from flowering to 10 and 15Brix was remarkably uniform despite contrasting seasons. Driving variables for weight loss during advanced ripening remain a matter of conjecture, but loss of berry water under highly evaporative conditions of late summer is a likely contributor.     

Unravelling the origin of Vitis vinifera L. Verdelho

Background and Aims

The history of Vitis vinifera L. cv. Verdelho has been studied, however, its geographic origin remains unknown. Although not widespread in mainland Portugal, Verdelho has gained a reputation as a Madeira wine, which has led most authors to attribute its origin to the Madeira Islands. The objective of this work was to determine the origin of Verdelho.

Methods and Results

An integrated strategy was followed, combining the molecular analysis of 28 nuclear and three chloroplast DNA microsatellites with an historical literature search. Historical records of the presence of Verdelho in the Azores Islands were found and these preceded those of the Madeira Islands by about 200 years. Moreover, the genetic analysis supports Verdelho as the progenitor of the Azores cultivars, Arinto dos Açores and Terrantez do Pico, and as the progeny of cv. Savagnin.

Conclusions

Verdelho is a key cultivar in the Azorean genetic diversity pool, sharing first‐degree relationships with the two most important autochthonous grape cultivars, and reinforcing the historical data of its ancestry in the region.

Significance of the Study

The results presented here, both historical and genetic, shed new light on the origin of Verdelho, and suggest that the Azores Islands is the site where this cultivar was likely to have originated.     

Characterization of Sultaniye grape (Vitis vinifera L. cv. Sultana) polyphenol oxidase

Polyphenol oxidase (PPO) was extracted from Sultaniye grapes grown in Turkey, and its characteristics in terms of pH and temperature optima, thermal inactivation, kinetic parameters and potency of some PPO inhibitors were studied. Optimum pH and temperature for grape PPO were found to be 3.4 and 30 °C, using catechol as substrate. K_m and V_max values were found to be 44.5 ± 5.47 mm and 0.695 ± 0.0353 OD₄₁₀ min^?1, respectively. Four inhibitors were tested in this study and the most potent inhibitor was sodium metabisulphite, followed by ascorbic acid. From the thermal inactivation studies in the range of 65–80 °C, the half‐life values of the enzyme ranged between 2.6 and 49.5 min. Activation energy (E_a) and Z values were calculated to be 208.5 kJ mol^?1 (r² = 0.9544) and 10.95 °C (r² = 0.9517), respectively.     

Multiple glucosyltransferase activities in the grapevine Vitis vinifera L.

The conjugation by glycosyltransferases of sugars to primary and secondary metabolites is widespread among plants and almost certainly a prerequisite for the accumulation of secondary metabolites at high levels. In the case of the grapevine, Vitis vinifera , modulating the levels of specific secondary berry metabolites is a desirable outcome for the development of wines with particular style characteristics. This can be achieved only by a thorough understanding of the processes underlying glucoside formation and accumulation during berry development. Using protein extracts prepared from leaves and berries of Vitis vinifera cvs, we show here that glucosyltransferase activities can be detected against a wide range of substrates. Among the substrates glucosylated were several classes of phenylpropanoids, including flavonols, anthocyanidins, flavanones, flavones, isoflavones, and a stilbene. Additionally, simple phenols and monoterpenes were glucosylated. Total soluble leaf proteins subjected to ion-exchange chromatography separated into fractions with differing glucosyltransferase activities. This provided strong evidence for the existence both of multiple distinct enzyme activities, and multiple isozymes catalysing identical reactions. Polyclonal antiserum raised to a V. vinifera UDP-glucose:anthocyanidin glucosyltransferase was used to demonstrate the existence of multiple glucosyltransferases in berries and leaves of the grapevine cvs Muscat of Alexandria and Shiraz, thereby confirming data obtained previously through biochemical analyses of recombinant glucosyltransferase.     

Inflorescence and bunch architecture development in Vitis vinifera L.

Inflorescence development from budburst to harvest was analysed in four cultivars of grapevine. Two cultivars with tight or compact bunches (Riesling, Chardonnay) and two with loose or open bunches (Exotic and Sultana) were selected to define differences in bunch development for future genetic analysis. A range of phenotypic characters for both inflorescence and shoot architecture were measured. Differences in the rate of rachis elongation rates were observed between tight and loose bunch cultivars commencing at the earliest stages of inflorescence development after budburst. At anthesis, five phenotypic characters showed significant differences between tight and loose cultivars: (1) total inflorescence length, (2) node number per inflorescence rachis, (3) combined length of two consecutive internodes of the rachis and (4) shoot node position at which the inflorescence was present and (5) mature tendril length. A quantitative estimate of bunch compactness was calculated at bunch maturity. Exotic and Sultana had significantly more open space than did compact bunch cultivars Riesling and Chardonnay. Comparison of flower number at anthesis and berry number at maturity indicated that the proportion of berries set was similar in all cultivars studied and, therefore, did not contribute to variability in bunch openness between cultivars. Internode length of the inflorescence rachis was the major trait responsible for inflorescence openness. Cellular studies using SEM, fluorescence microscopy and DNA content demonstrated that differences in rachis internode lengths were mostly associated with cell expansion.     

Effect of low temperature near flowering time on ovule development and pollen tube growth in the grapevine (Vitis vinifera L.), cvs Chardonnay and Shiraz

To study ovule development, small Chardonnay and Shiraz vines were grown in pots under controlled conditions at 25°/20°C day/night temperature until flowering or were transferred to 12°/9°C two days before flowering and then returned to 25°/20°C after one week. The ovules of flowers at three positions within the inflorescence were excised on the day after they had opened. The ovules exposed to the lower temperatures tended to be smaller and less advanced in development, even when otherwise normal, especially on Chardonnay, and the ovules of king flowers tended to be larger than those of the other flowers. Over half of the ovules of Chardonnay exposed to the low temperatures were abnormal (with abnormal or no embryo sacs, and some also having a degenerated nucellus) while 35% of the Shiraz ovules were without normal embryo sacs. To study pollination and pollen tube growth, vines similar to those of the ovule study were exposed to 12°/9°C two days before or on the day of flowering. In the pistils exposed to low temperature, a reduction occurred in the number of pollen tubes present in the lower ovary on days 2 and 4 after flowering, from about four to almost nil in Chardonnay, but a smaller reduction occurred in Shiraz. In the absence of cool temperatures, pollen tubes penetrated on average less than one ovule per ovary in Chardonnay and about one ovule per ovary in Shiraz. It is concluded that temperature sensitivity to fruit-set is a varietal characteristic, expressing itself in quantitative differences in the damage imparted to the structure of the ovules and the function of the pollen.     

Projecting the impacts of climate change on the phenology of grapevine in a mountain area

Background and Aims: The strong link between climate and grapevine phenology suggests a potentially stronger impact of climate change on viticulture in climate‐limited areas, including mountain zones. The aim of this work was to evaluate the potential effects of climate change on grapevine phenology and viticultural suitability in a mountain region. Methods and Results: Climatic projections were applied to phenological models to determine the effect on stages of budburst, flowering and veraison for Vitis vinifera cv. Chardonnay. Calibration and validation of the models had been previously carried out in the same alpine region. The output of the general‐circulation climatic model HadCM3, run with two different Intergovernmental Panel on Climate Change emission scenarios, was statistically downscaled to 10 locations in different agricultural sites in Trentino, Italian Alps, some of which are presently unfit for viticulture due to climatic limitations. Results yielded a trend of phenological advance, with interesting differences among phases and sites. Simulated advance was more pronounced at higher elevations, and larger for veraison than for spring phenophases. Conclusions: As a consequence of the considerable warming projected by future climate scenarios, some mountain sites at about 1000 m were expected to fall within areas climatically suitable for viticulture before the end of this century. Nevertheless, noticeable differences from present conditions are not expected within a short timescale. Significance of the Study: These projections, suggesting a more pronounced phenological response at higher elevations, may support the development of adaptation strategies aimed at maintaining the profitability of mountain viticulture even in times of global change.     

Auxin treatment of pre‐veraison grape (Vitis vinifera L.) berries both delays ripening and increases the synchronicity of sugar accumulation

Background and Aims: Pre‐veraison auxin treatments can delay grape berry ripening, but there is little information about their effects on berry development and wine composition. The aim of this study was to further investigate these effects and explore the practical implications of delaying ripening. Methods and Results: Treatment of pre‐veraison Vitis vinifera L. cv. Shiraz berries with 1‐naphthaleneacetic acid (NAA) significantly delayed ripening as measured by the accumulation of total soluble solids (TSS) and anthocyanins. The onset of the post‐veraison phase of berry size increase was delayed in NAA‐treated fruit, but these fruit were significantly larger than Control fruit at harvest. NAA‐treatments significantly increased the synchronicity of berry sugar accumulation. GC‐MS analysis of wine headspace volatiles showed significant, but largely small, differences in the concentration of 19 compounds. No significant difference in sensory properties was found between replicate small‐scale wine lots made from Control and NAA‐treated fruit. Conclusions: Auxin treatment delayed berry ripening, increased the synchronicity of sugar accumulation between berries, increased berry size and changed the levels of some volatile compounds, but did not affect wine sensory properties. Significance of the Study: We propose that NAA sprays might be used to delay grape berry ripening and increase the synchronicity of sugar accumulation, and therefore ripening, without deleterious effects on wine quality. This may be useful in controlling winery intake and fruit composition.     

琐琐葡萄总黄酮提取工艺

研究琐琐葡萄果实总黄酮的醇法提取工艺。在考察各影响因素的基础上设计正交试验,得出各种因素对提取效果影响的主次顺序为料液比＞提取时间＞提取温度＞乙醇体积分数,总黄酮提取最佳工艺条件为：提取温度80℃、乙醇体积分数60%、提取时间120min、料液比1:30(g/mL)。     

Light and temperature effects on shoot fruitfulness in Vitis vinifera L. cv. Sultana: Influence of trellis type and grafting

Fruit bud initiation in Sultana is more sensitive to climatic factors than fruit bud initiation in other cultivars. This paper considers historical findings regarding the influence of light and temperature on fruit bud initiation and fruitfulness in view of modern Sultana vineyard management practices.
Past results were reviewed and confirmed by experiments in which variability in vine size and structure was introduced by grafting and modifications of trellis design. Ramsey-grafted vines were consistently less fruitful than own-rooted Sultana, possibly because of a more shaded canopy interior due to greater vegetative growth of vines grafted to Ramsey rootstock. Carbohydrate reserves of node and internode tissue in late winter between node 2 and 18 followed a similar trend along the cane as fruitfulness in the following spring.