Berry Ripening Research Articles

Polyphenols composition and anti-diabetic properties in vitro of haskap (Lonicera caerulea L.) berries in relation to cultivar and harvesting date

Haskap (Lonicera caerulea L.) is a recently commercialized fruit crop in Canada. Berries of four cultivars, Aurora, Rebecca, Larissa, and Evie, were harvested at five harvesting dates (H1-H5) and assessed for their polyphenol composition and anti-diabetic potential in vitro. The analyses revealed that the interaction effect of cultivar and harvesting date influenced the concentration of anthocyanins. Cyanidin-3-O-glucoside represents about 79 % of total anthocyanins present in ripened haskap berries. Total anthocyanins estimated by a non-destructive method showed a strong correlation for quantified anthocyanin by liquid chromatography-mass spectrometry (UPLC-ESI-MS), indicating the potential application of the non-destructive method for deciding the berry maturity for mechanical harvesting of haskap berry for value-added processing. Extracts derived from five maturity stages of four cultivars showed anti-diabetic properties including inhibition of activities of alpha-amylase (IC50 ranges from 2380 to 5080 μg/mL), alpha-glucosidase (IC50 ranges from 1130 to 2120 μg/mL), dipeptidyl peptidase-4 (DPP-4, IC50 ranges from 2150 to 11,600 μg/mL), and formation of advanced glycation end-products (AGE, IC50 ranges from 1200 to 4790 μg/mL) in vitro. Though the impact of harvesting date on polyphenol composition is very distinct, the extracts of late harvesting date (H5) reduced the anti-diabetic activities in vitro only in Aurora and Larisa cultivars. Inhibition of DPP-4 and AGE formation dependent on cultivar and harvesting date. Haskap berry warrants further investigation as a dietary therapeutic to manage type 2 diabetes.

HIGH-MOLECULAR COMPOUNDS IN THE MUST OF NEW VARIETIES AND CLONES OF THE GRAPES

The stability of grape plant to low temperatures depends on many factors, including the synthesis of proteins, polyphenols, polysaccharides, which fulfill shielding functions in the plant. A deep reconstruction of respiratory system and linked biochemical processes occur in the process of hardening, which lead to the accumulation of high-molecular compounds (especially starch) in leaves and the rod, that are been basic spare substances in the winter period. Meanwhile changes of the high-molecular connections in the juice of berries are virtually not investigated. This problem is urgent for the grape processing industries, since high-molecular connections affect the quality of finished production. Purpose of the work is to evaluate the concentrations of high-molecular connections in the juice of berries from the new types, including hybrids and the clones, which possess stress resistance to the external factors. Laboratory investigations are carried out on the base of CCU “Instrument-analytical” and of scientific center “Winemaking” FSBSO NCFSCHVW with the application of spectral method (spectrophotometers UNICO 2800, LEKI SS1207) and electrophoresis in polyacryl gel. It is established that protein concentration in the must of classical types and their clones has close values. The most higher concentration of proteins was found in the must of hybrid varieties (up to 45 mg/dm3, Bianka variety). The analysis of electrophoresis spectra testifies the heterogeneity of the molecular weights of proteins in the must of classical and hybrid varieties. The starch is identified in mature grapes of white varieties with the mass concentration of sugar 12–14 g/100 cm3 from 8.6 to 28.7 mg/dm3 and in the juice of the mature grapes of red varieties from 12.4 (to 38.6 mg/dm3 that correlates with the frost resistance of the studied varieties and clones. Starch concentration in the juice decreases with the complete technical maturity of berries. However, a starch amount was significantly smaller in a number of the varieties with average and low frost resistance. Thus, the represented results testify about a substantial change of the high-molecular compounds in the stress-resistant varieties and the clones in the comparison with the classical European types.

Hormonal and transcriptional analyses of fruit development and ripening in different varieties of black pepper (Piper nigrum).

Black pepper (Piper nigrum L.) is one of the most popular and oldest spices in the world with culinary uses and various pharmacological properties. In order to satisfy the growing worldwide demand for black pepper, improved productivity of pepper is highly desirable. A primary constraint in black pepper production is the non-synchronous nature of flower development and non-uniform fruit ripening within a spike. The uneven ripening of pepper berries results in a high labour requirement for selective harvesting contributes to low productivity and affects the quality of the pepper products. In Malaysia, there are a few recommended varieties for black pepper planting, each having some limitations in addition to the useful characteristics. Therefore, a comparative study of different black pepper varieties will provide a better understanding of the mechanisms regulates fruit development and ripening. Plant hormones are known to influence the fruit development process and their roles in black pepper flower and fruit development were inferred based on the probe-based gene expression analysis and the quantification of the multiple plant hormones using high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). In this study, jasmonic acid and salicylic acid were found to play roles in flowering and fruit setting, whereas auxin, gibberellin and cytokinins are important for fruit growth. Abscisic acid has positive role in fruit maturation and ripening in the development process. Distinct pattern of plant hormones related gene expression profiles with the hormones accumulation profiles suggested a complex network of regulation is involved in the signaling process and crosstalk between plant hormones was another layer of regulation in the black pepper fruit development mechanisms. The current study provides clues to help in elucidating the timing of the action of each specific plant hormone during fruit development and ripening which could be applied to enhance our ability to control the ripening process, leading to improving procedures for the production and post-harvest handling of pepper fruits.

Tannin content and antioxidant capacity of five Greek red grape varieties.

Tannins are located in skins and seeds and are responsible for important sensory and quality attributes of red grapes and wines, such as astringency, bitterness and colour stability. However, little is known regarding Greek Vitis vinifera varieties. The aim of this study is to evaluate the grape phenolic content and to present data that may contribute to the development of suitable winemaking techniques for these varieties. In this study berry attributes, skin and seed content of tannins and antioxidant capacity from five Greek Vitis vinifera varieties, namely 'Mavrotragano', 'Mandilaria', 'Kotsifali', 'Agiorgitiko' and 'Xinomavro' were analyzed. Significant differences were observed in berry weight and the distribution of berry component mass in mature berries, among the different varieties. 'Mandilaria' and 'Kotsifali' had the heavier berries while the higher contribution of skins and seeds in berry was observed in 'Agiorgitiko' and 'Mavrotragano' grapes respectively. According to the results, the higher content of seed tannins in berries was determined in 'Mandilaria' and the lower in 'Kotsifali'. Finally, varieties with high concentrations of tannins, 'Mandilaria' and 'Mavrotragano', also demonstrated significant high values of antioxidant capacity.

Using forced regrowth to manipulate Chardonnay grapevine (Vitis vinifera L.) development to evaluate phenological stage responses to temperature

Time and environmental conditions, such as temperature and photoperiod, are the main drivers governing grapevine development over the growing season. The most obvious growth periods in grapevines are budbreak, bloom, veraison and berry maturity. The aims of this study were to evaluate the environmental and physiological factors influencing the phenological development of Chardonnay grapevines, and to determine the best fit parameters of degree-day calculation methods for the prediction of various phenological stages. Phenological data retrieved from field vines and vines forced to regrow after heavy pruning and defoliation, whose developmental onset conditions were modified, were used to test and parameterize the degree-day calculation methods. An upper temperature threshold (TU) was optimized for the different developmental stages, and measures of the radiation use efficiency were derived to adjust TU during berry maturity. According with the candidate methods, the highest TU value coincided with bloom (29.8ºC), while the lowest was observed at veraison (20.9ºC). The RMSE of the model predictions for specific developmental stages ranged from 2 (fruit set) to 9 days (berry maturity). Modifying vine growth periods by forcing vine regrowth allowed evaluation of temperature and physiological factors that influence grapevine development.

Comparative physiological, metabolomic, and transcriptomic analyses reveal developmental stage-dependent effects of cluster bagging on phenolic metabolism in Cabernet Sauvignon grape berries

BackgroundLight conditions significantly influence grape berry ripening and the accumulation of phenolic compounds, but the underlying molecular basis remains partially understood. Here, we applied integrated transcriptomics and pathway-level metabolomics analyses to investigate the effect of cluster bagging during various developmental stages on phenolic metabolism in Cabernet Sauvignon grapes.ResultsBagging treatments had limited effects on berry quality attributes at harvest and did not consistently affect phenolic acid biosynthesis between seasons. Significantly elevated flavan-3-ol and flavonol contents were detected in re-exposed berries after bagging during early-developmental stages, while bagging after véraison markedly inhibited skin anthocyanin accumulation. Several anthocyanin derivatives and flavonol glycosides were identified as marker phenolic metabolites for distinguishing bagged and non-bagged grapes. Coordinated transcriptional changes in the light signaling components CRY2 and HY5/HYHs, transcription regulator MYBA1, and enzymes LAR, ANR, UFGT and FLS4, coincided well with light-responsive biosynthesis of the corresponding flavonoids. The activation of multiple hormone signaling pathways after both light exclusion and re-exposure treatments was inconsistent with the changes in phenolic accumulation, indicating a limited role of plant hormones in mediating light/darkness-regulated phenolic biosynthesis processes. Furthermore, gene-gene and gene-metabolite network analyses discovered that the light-responsive expression of genes encoding bHLH, MYB, WRKY, NAC, and MADS-box transcription factors, and proteins involved in genetic information processing and epigenetic regulation such as nucleosome assembly and histone acetylation, showed a high positive correlation with grape berry phenolic accumulation in response to different light regimes.ConclusionsAltogether, our findings provide novel insights into the understanding of berry phenolic biosynthesis under light/darkness and practical guidance for improving grape features.

Bagging Affecting Sugar and Anthocyanin Metabolism in the Ripening Period of Grape Berries

Grapevine is one of the most important fruit-bearing plants worldwide, for which bagging treatments can effectively improve fruit quality. However, the low-light conditions caused by bagging can delay grape berry maturation. Here, we analyzed glucose, fructose, and anthocyanin contents and the expression of sugar and anthocyanin-metabolism pathway genes in the grape berries of two cultivars, ‘Shenhua’ and ‘Shenfeng’, under different bagging treatments. Color development was incomplete in bagged grape berries and their soluble sugar contents were lower than those detected in un-bagged fruits. However, fruit color and SSC could be rapidly restored to normal levels after removing bags. Light affects the accumulation of sugar in grape berries, especially near the maturation period, as well as the contents and compositions of anthocyanins in the skin of grape berries. Although light helps in the accumulation of anthocyanins, significant differences were detected in anthocyanin composition between the two grapevine varieties. In addition, the expressions of myofibroblastic regulatory genes in the anthocyanin pathway were affected by light, and the light-responsive elements elongated hypocotyl 5 and constitutive photomorphogenic 1 acted synergistically to control grape berry coloration. Overall, these results provide a theoretical basis for the maturation mechanism in grape berries.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Grape Berry Flavonoid Responses to High Bunch Temperatures Post Véraison: Effect of Intensity and Duration of Exposure.

Climate models predict an increase in the frequency and duration of heatwaves with an increase in intensity already strongly evident worldwide. The aim of this work was to evaluate the effect of two heatwave-related parameters (intensity and duration) during berry ripening and identify a threshold for berry survival and flavonoid accumulation. A Doehlert experimental design was used to test three temperature intensities (maxima of 35, 46, and 54 °C) and five durations (3 to 39 h), with treatments applied at the bunch level shortly after véraison. Berry skin and seeds were analysed by liquid chromatography-triple quadrupole-mass spectrometry (LC-QqQ-MS) for flavonoids (flavonols, anthocyanins, free flavan-3-ols, and tannins). Berries exposed to 46 °C showed little difference compared to 35 °C. However, berries reaching temperatures around 54 °C were completely desiccated, and all flavonoids were significantly decreased except for skin flavonols on a per berry basis and seed tannins in most cases. Some compounds, such as dihydroxylated flavonoids and galloylated flavan-3-ols (free and polymerised), were in higher proportion in damaged berries suggesting they were less degraded or more synthesised upon heating. Overall, irreversible berry damages and substantial compositional changes were observed and the berry survival threshold was estimated at around 50–53 °C for mid-ripe Shiraz berries, regardless of the duration of exposure.

Characterization of VvSPL18 and Its Expression in Response to Exogenous Hormones during Grape Berry Development and Ripening

The sequence and structure of grape SBP-box-like18 (VvSPL18) were identified and characterized to explore its regulatory roles during grape berry development and ripening. Homologous conservation across diverse plant species was observed, and its potential function and modulated roles in grapes were investigated. The results showed that VvSPL18 has an ORF sequence of 1,137 bp, encodes 378 amino acids, and is located on chromosome 14 of grapevine. VvSPL18 has the closest relationship with its homolog in soybeans. The promoter of VvSPL18 contains cis-elements responsive to gibberellins (GA) and salicylic acid (SA), indicating that this gene might respond to these hormones involved in the modulation of grape berry. VvSPL18 is mainly distributed in the nucleus. Expression profiles showed that VvSPL18 is highly expressed only at the veraison stage of the grape berry and is slightly expressed in other phases. RNA-seq data also revealed that VvSPL18 might participate in the modulation of grape berry development and ripening. Treatment with diverse hormones demonstrated that abscisic acid (ABA) had almost no effect on its expression, whereas naphthalene acetic acid (NAA) significantly upregulated its expression at the veraison stage. We also found that VvSPL18 has a GA-responsive cis-element but no NAA-responsive cis-element. GA could promote the expression of VvSPL18 with a peak at an earlier stage than NAA, suggesting that VvSPL18 responds faster to GA than to NAA. This result indicates that VvSPL18 might modulate berry development at this phase through an ABA-independent pathway, and it might directly respond to GA, but indirectly to NAA. Our findings provide insights into the functions of VvSPL18 in mediating grape berry development and ripening.

Functional Characterization of the Grapevine γ-Glutamyl Transferase/Transpeptidase (E.C. 2.3.2.2) Gene Family Reveals a Single Functional Gene Whose Encoded Protein Product Is Not Located in Either the Vacuole or Apoplast.

γ-glutamyl transferases/transpeptidases (E.C. 2.3.2.2, GGTs) are involved in the catabolism of many compounds that are conjugated to glutathione (GSH), which have a variety of roles. GSH can act as storage and transport vehicle for reduced sulfur; it is involved in the detoxification of xenobiotics and also acts as a redox buffer by utilizing its thiol residue to protect against reactive oxygen species, which accumulate in response to biotic and abiotic stress. Furthermore, many distinctive flavor and aroma compounds in Sauvignon blanc wines originate from odorless C5- and C6-GSH conjugates or their GGT catabolized derivatives. These precursors are then processed into their volatile forms by yeast during fermentation. In many plant species, two or more isoforms of GGTs exist that target GSH-conjugates to either the apoplast or the vacuole. A bioinformatics approach identified multiple GGT candidates in grapevine (Vitis vinifera). However, only a single candidate, VvGGT3, has all the conserved residues needed for GGT activity. This is intriguing given the variety of roles of GSH and GGTs in plant cells. Characterization of VvGGT3 from cv. Sauvignon blanc was then undertaken. The VvGGT3 transcript is present in roots, leaves, inflorescences, and tendril and at equal abundance in the skin, pulp, and seed of mature berries and shows steady accumulation over the course of whole berry development. In addition, the VvGGT3 transcript in whole berries is upregulated upon Botrytis cinerea infection as well as mechanical damage to leaf tissue. VvGGT3-GFP fusion proteins transiently over-expressed in onion cells were used to study subcellular localization. To confirm VvGGT3 activity and localization in vivo, the fluorescent γ-glutamyl-7-amido-4-methylcoumarin substrate was added to Nicotiana benthamiana leaves transiently over-expressing VvGGT3. In combination, these results suggest that the functional VvGGT3 is associated with membrane-like structures. This is not consistent with its closely related functionally characterized GGTs from Arabidopsis, radish and garlic.

Various Patterns of Composition and Accumulation of Steroids and Triterpenoids in Cuticular Waxes from Screened Ericaceae and Caprifoliaceae Berries during Fruit Development.

Cuticular waxes are primarily composed of two classes of lipids: compounds derived from very-long-chain fatty acids and isoprenoids, particularly triterpenoids and steroids. Isoprenoids can occur in cuticular waxes in high amounts, dominating the mixture of aliphatic long-chain hydrocarbons, while in other plants they are found in trace concentrations. Triterpenoids occurring in fruit cuticular waxes are of interest due to their potential role in the protection against biotic stresses, including pathogen infections, and their impact on the mechanical toughness of the fruit surface, maintaining fruit integrity, and post-harvest quality. The aim of the present study was the determination of the changes in the triterpenoid profile of the fruit cuticular waxes of four plant species bearing edible berries: Vaccinium myrtillus, V. vitis-idaea, and Arbutus unedo of the Ericaceae and the edible honeysuckle Lonicera caerulea of the Caprifoliaceae. Triterpenoids were identified and quantified by GC-MS/FID (gas chromatography-mass spectrometry/flame ionization detection) at three different phenological stages: young berries, berries at the onset of ripening, and mature berries. During fruit development and maturation, the triterpenoid content in cuticular waxes displayed species-specific patterns of changes. The steroid content seemed to be directly correlated with the developmental stage, with a very typical point of transition between growth and ripening being observed in all the fruit analyzed in this study.

An Interactive Web Application for Predicting Ripening of Bilberry (Vaccinium myrtillus) in Finland

I used a temperature-sum model to predict the ripening of bilberries (Vaccinium myrtillus) on a daily basis, using real-time temperature data. The temperature-sum model was developed by fitting to historical data on berry ripening, and by finding a parameter combination that minimizes the model prediction error. The model was then used to predict the timing of berry ripening by using temperature data for a 10 × 10-km grid that covered the entire of Finland. The berry ripening predictions were presented online on a map showing the berry ripening predictions in real time. One third of the users indicated that the model predictions were correct, and another third pointed out that the first berries were already ripened when the model predicted ripening to take place. I, therefore, conclude that the model predicts the bilberry ripening with good accuracy.

Selection of candidate genes controlling veraison time in grapevine through integration of meta-QTL and transcriptomic data

BackgroundHigh temperature during grape berry ripening impairs the quality of fruits and wines. Veraison time, which marks ripening onset, is a key factor for determining climatic conditions during berry ripening. Understanding its genetic control is crucial to successfully breed varieties more adapted to a changing climate. Quantitative trait loci (QTL) studies attempting to elucidate the genetic determinism of developmental stages in grapevine have identified wide genomic regions. Broad scale transcriptomic studies, by identifying sets of genes modulated during berry development and ripening, also highlighted a huge number of putative candidates.ResultsWith the final aim of providing an overview about available information on the genetic control of grapevine veraison time, and prioritizing candidates, we applied a meta-QTL analysis for grapevine phenology-related traits and checked for co-localization of transcriptomic candidates. A consensus genetic map including 3130 markers anchored to the grapevine genome assembly was compiled starting from 39 genetic maps. Two thousand ninety-three QTLs from 47 QTL studies were projected onto the consensus map, providing a comprehensive overview about distribution of available QTLs and revealing extensive co-localization especially across phenology related traits. From 141 phenology related QTLs we generated 4 veraison meta-QTLs located on linkage group (LG) 1 and 2, and 13 additional meta-QTLs connected to the veraison time genetic control, among which the most relevant were located on LG 14, 16 and 18. Functional candidates in these intervals were inspected. Lastly, taking advantage of available transcriptomic datasets, expression data along berry development were integrated, in order to pinpoint among positional candidates, those differentially expressed across the veraison transition.ConclusionIntegration of meta-QTLs analysis on available phenology related QTLs and data from transcriptomic dataset allowed to strongly reduce the number of candidate genes for the genetic control of the veraison transition, prioritizing a list of 272 genes, among which 78 involved in regulation of gene expression, signal transduction or development.

Aminoacids and Flavonoids Profiling in Tempranillo Berries Can Be Modulated by the Arbuscular Mycorrhizal Fungi.

(1) Background: Vitis vinifera L. cv. Tempranillo is cultivated over the world for its wine of high quality. The association of Tempranillo with arbuscular mycorrhizal fungi (AMF) induced the accumulation of phenolics and carotenoids in leaves, affected the metabolism of abscisic acid (ABA) during berry ripening, and modulated some characteristics and quality aspects of grapes. The objective of this study was to elucidate if AMF influenced the profiles and the content of primary and secondary metabolites determinants for berry quality in Tempranillo. (2) Methods: Fruit-bearing cuttings inoculated with AMF or uninoculated were cultivated under controlled conditions. (3) Results: Mycorrhizal symbiosis modified the profile of metabolites in Tempranillo berries, especially those of the primary compounds. The levels of glucose and amino acids clearly increased in berries of mycorrhized Tempranillo grapevines, including those of the aromatic precursor amino acids. However, mycorrhizal inoculation barely influenced the total amount and the profiles of anthocyanins and flavonols in berries. (4) Conclusions: Mycorrhizal inoculation of Tempranillo grapevines may be an alternative to the exogenous application of nitrogen compounds in order to enhance the contents of amino acids in grapes, which may affect the aromatic characteristics of wines.

Relationship between anthocyanins and skin color of table grapes treated with abscisic acid at different stages of berry ripening

Grapes grown under warm climate conditions tend to show less color development, and this phenomenon is attributed to low anthocyanin accumulation in berry skin in response to high temperature during ripening. ‘Benitaka’ (Vitis vinifera L.) is a table grape that shows poor color development when grown under a subtropical condition, and the exogenous application of (S)-cis-abscisic acid (S-ABA) is a recently developed technique used to overcome this difficulty. Trials were conducted during two crop seasons in a commercial vineyard containing 11-year-old ‘Benitaka’ vines grafted onto ‘IAC 766 Campinas’ rootstocks in Marialva, State of Parana (PR), Brazil. The vines were trained on an overhead trellis system, covered with a black plastic mash, and spaced 3.0 × 6.0 m apart. A randomized block design was used and treatments included the application of 400 mg L−1 of S-ABA at different stages of ripening, as follows: Control (no application); At pre-veraison (PRV) (7 days before veraison); At veraison (V); and At post-veraison (POV) (7 days after V). A second application was performed for all treatments, 10 days after the first application, except for the control. The analysis of berries included, total and daily anthocyanins accumulation, the color index of red grapes (CIRG), daily CIRG development, lightness (L*), chroma (C*), hue angle (h°), mass, length, width, firmness, total soluble solids (TSS), titratable acidy (TA), the index of maturation (TSS/TA), and total polyphenols of berries. The exogenous application of S-ABA from PRV to POV significantly enhanced the contents and rates of total anthocyanins accumulation and the CIRG of ‘Benitaka’ table grape; however, the application at PRV and V provided a higher response. A stronger correlation exists between anthocyanin concentration and the color index of berry skin, however, the main physicochemical characteristics of berries are not significantly affected by the use of S-ABA. Berry firmness varies in response to S-ABA application, but not to an extent at which it compromises berry quality for commercial use.

Chemical Composition, In Vitro Antioxidant Potential, and Antimicrobial Activities of Essential Oils and Hydrosols from Native American Muscadine Grapes

Essential oils and hydrosols of two cultivars of muscadine grapes (Muscadinia rotundifolia (Michx.) Small.) were obtained by hydro-distillation of flowers and berry skins. Twenty-three volatile compounds were identified in essential oils from the muscadine flowers, and twenty volatiles in their corresponding hydrosols. The composition of volatiles in berry skins differed significantly from that of the vine flowers. The antioxidant potential of investigated essential oils and hydrosols was evaluated using five in vitro assays: DPPH (2,2-diphenyl-1-picrylhydrazyl) method, TEAC (Trolox equivalent antioxidant capacity), FRAP (Ferric reducing antioxidant power), CUPRAC (cupric ion reducing antioxidant capacity), and NO (nitric oxide radical scavenging assay). The essential oils from the flowers of both cultivars showed the strongest antioxidant power, whereas the hydrosols were the significantly less active. All investigated essential oils showed very weak antibacterial activities against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. However, the essential oils from the flowers of both cultivars showed moderate antifungal activities against Candida albicans, which were stronger for the oil from “Carlos” (white muscadine cultivar). To the best of our knowledge, this is the first report on obtaining and characterizing essential oils and hydrosols from muscadine grapes. This study demonstrated the variations in aromatic compounds accumulated in flowers and mature berry skins of muscadine grapes, and evaluated their possible antioxidant and antimicrobial activities. The presented results will be the base for future research, focused on a better understanding of the molecular and regulatory mechanisms involved in aromatic compound biosynthesis and accumulation in muscadine grapes.

Malate Content in Wild Vitis spp. Demonstrates a Range of Behaviors during Berry Maturation

Wild <i>Vitis</i> spp. and their interspecific hybrids are known to have high malate concentrations at sugar maturity as compared to domesticated <i>Vitis vinifera</i>, but it is unknown if differences in malate at harvest among species arise from differences in malate accumulation or degradation. Over two years, fruit from <i>Vitis riparia</i> and <i>Vitis cinerea</i> accessions along with commercial <i>V. vinifera</i> and interspecific hybrid cultivars were collected at multiple time points. In contrast to the well-known biphasic behavior of malate in <i>V. vinifera</i> (preveraison accumulation, postveraison degradation), we observed a range of behaviors for malate in wild species. On average, <i>V. riparia</i> accessions had malate per berry comparable to <i>V. vinifera</i> just prior to veraison, but degraded malate to a much lesser extent. <i>V. cinerea</i> accessions had lower malate prior to veraison than other species but showed an increase in malate from pre- to postveraison. Variation in postveraison malate behavior appears related to diminished malate degradation in the mesocarp of wild <i>Vitis</i> spp. Our results indicate that studies of malate behavior in <i>Vitis</i> spp. and their hybrids should include both pre- and postveraison time points.

Variation of Anthocyanin Content and Profile Throughout Fruit Development and Ripening of Highbush Blueberry Cultivars Grown at Two Different Altitudes.

Blueberry (Vaccinium corymbosum L.) is a widely consumed fruit and a rich source of bioactive compounds, namely, the polyphenol class of anthocyanins. Little information is available about the influence of internal (genetic and developmental) and external (environmental) factors on the levels of phenolic metabolites in blueberry fruit. In light of this consideration, total polyphenolic and flavonoid content, anthocyanin accumulation and composition were evaluated in cv. “Duke” and “Brigitta” grown at two different altitudes in Valtellina, a valley of the Alps in Northern Italy. During berry ripening, there is a developmentally coordinated shift from cyanidin-type, di-substituted anthocyanins toward delphinidin-based, tri-substituted pigments. At the lower altitude location, higher temperatures, not exceeding optimum, resulted in a more quickly berry developmental pattern and in higher anthocyanin concentrations in the early phases of ripening. At later stages of ripening, berries of both cultivars at higher altitude compensate for these initial temperature effects, and no differences were recorded in ripe fruit grown in the two locations. We conclude that anthocyanin accumulation is strongly regulated by development and genotype, and the environmental factors, associated to the altitude gradient, exert in the trial conditions only a fine-tuning influence. Fruits reach the full-ripening stage simultaneously at both sites because the initial gap in pigment levels is counterbalanced at the higher altitude by a faster rate of accumulation at later phases of the ripening process.

Effect of Riboflavin on the Precocious Maturation of Spine Grape Berries (Vitis davidii Foex)

Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide economical and environmentally safe ways to promote the precocious maturation of spine grape berries, the effects of riboflavin were investigated. Riboflavin affected the reactive oxygen species metabolism in spine grape berries by increasing superoxide radical production and the hydrogen peroxide content, and it impaired the activities of the antioxidant enzymes superoxide dismutase and catalase. Riboflavin also induced the upregulated expression of maturation-related genes in advance, and the earlier accumulation of anthocyanin and total soluble solids. Phenological observations revealed that the treated grape berries underwent a color-turning stage 9 days earlier than the control, and the maturation stage occurred 7 days earlier than the control. Thus, riboflavin may significantly promote the precocious maturation of spine grape berries.

Foliar Applications of Biostimulants Promote Growth, Yield and Fruit Quality of Strawberry Plants Grown under Nutrient Limitation

Biostimulants have been found effective in enhancing plant resistance toward stressful conditions. The aim of the present study was to evaluate the efficacy of selected biostimulants to overcome the negative effects of nutrient limitation on the growth performances and on the fruit quality of soilless cultivated strawberry plants. The condition of nutrient limitation was imposed by supplying the plants with only a single fertilization at transplantation and by excluding any further nutrient supply for the entire duration of the experiment (three months, from May to July). Strawberry plants were treated seven times during the period from preflowering up to berry maturation with different classes of biostimulants (humic acids, alfalfa hydrolysate, macroseaweed extract and microalga hydrolysate, amino acids alone or in combination with zinc, B-group vitamins, chitosan, and a commercial product containing silicon) at commercial dosages. The use of alfalfa hydrolysate, vitamins, chitosan, and silicon was able to promote biomass accumulation in roots (four to seven folds) and fruits (+20%) of treated plants, whereas the total leaf area increased by 15%–30%. Nutrient concentrations in leaves and roots showed variations for microelements (e.g., Fe, B, Zn, and Si) in response to biostimulant applications, whereas no significant differences were observed for macronutrient contents among treatments. Final berry yield was found around 20% higher in chitosan- and silicon-treated plants. Chitosan treatment significantly increased pulp firmness (by 20%), while a high nutritional value (e.g., phenolic compounds concentration) was observed in alfalfa- and seaweed-treated fruits (+18%–20% as compared to control). The overall outcomes of the present experiment show that selected biostimulants can be considered as a valid agronomic tool able to contrast the negative consequence of growing crops under insufficient nutritional conditions.