- Proceedings of the National Academy of Sciences of the United States of America
- Published about 7 years ago
Wine grapes present a unique biogeography model, wherein microbial biodiversity patterns across viticultural zones not only answer questions of dispersal and community maintenance, they are also an inherent component of the quality, consumer acceptance, and economic appreciation of a culturally important food product. On their journey from the vineyard to the wine bottle, grapes are transformed to wine through microbial activity, with indisputable consequences for wine quality parameters. Wine grapes harbor a wide range of microbes originating from the surrounding environment, many of which are recognized for their role in grapevine health and wine quality. However, determinants of regional wine characteristics have not been identified, but are frequently assumed to stem from viticultural or geological factors alone. This study used a high-throughput, short-amplicon sequencing approach to demonstrate that regional, site-specific, and grape-variety factors shape the fungal and bacterial consortia inhabiting wine-grape surfaces. Furthermore, these microbial assemblages are correlated to specific climatic features, suggesting a link between vineyard environmental conditions and microbial inhabitation patterns. Taken together, these factors shape the unique microbial inputs to regional wine fermentations, posing the existence of nonrandom “microbial terroir” as a determining factor in regional variation among wine grapes.
BACKGROUND: Vegetative buds provide plants in temperate environments the possibility for growth and reproduction when environmental conditions are favorable. In grapevine, crucial developmental events take place within buds during two growing seasons in consecutive years. The first season, the shoot apical meristem within the bud differentiates all the basic elements of the shoot including flowering transition in lateral primordia and development of inflorescence primordia. These events practically end with bud dormancy. The second season, buds resume shoot growth associated to flower formation and development. Gene expression has been previously monitored at specific stages of bud development but has never been followed along the two growing seasons. RESULTS: Gene expression changes were analyzed along the bud annual cycle at eight different time points. Principal Components Analysis (PCA) revealed that the main factors explaining the global gene expression differences were the processes of bud dormancy and active growth as well as stress responses. Accordingly, non dormant buds showed an enrichment in functional categories typical of actively proliferating and growing cells together with the over abundance of transcripts belonging to stress response pathways. Differential expression analyses performed between consecutive time points indicated that major transcriptional changes were associated to para/endodormancy, endo/ecodormancy and ecodormancy/bud break transitions. Transcripts encoding key regulators of reproductive development were grouped in three major expression clusters corresponding to: (i) transcripts associated to flowering induction, (ii) transcripts associated to flower meristem specification and initiation and (iii) transcripts putatively involved in dormancy. Within this cluster, a MADS-box gene (VvFLC2) and other transcripts with similar expression patterns could participate in dormancy regulation. CONCLUSIONS: This work provides a global view of major transcriptional changes taking place along bud development in grapevine, highlighting those molecular and biological functions involved in the main events of bud development. As reported in other woody species, the results suggest that genes regulating flowering could also be involved in dormancy regulatory pathways in grapevine.
BACKGROUND: Resveratrol is an important stilbene that benefits human health. However, it is only distributed in a few species including grape and is very expensive. At present, grape has been an important source resveratrol. However, the details are scarce on resveratrol distribution in different Vitis species or cultivars. METHODOLOGYPRINCIPAL FINDING: The composition and content of resveratrols were investigated by HPLC for assessing genotypic variation in berry skins and leaves of 75 grape cultivars, belonging to 3 species and 7 interspecific hybrids. Trans-resveratrol, cis-piceid and trans-piceid were detected in berry skins and leaves, but cis-resveratrol was not. Resveratrol content largely varied with genetic background as well as usage. In most cultivars, total resveratrol including the above three compounds was higher in berry skins than leaves. In berry skins of most cultivars and leaves of almost all cultivars, cis-piceid was the most abundant resveratrol; trans-resveratrol and trans-piceid were minor components. Some specific cultivars were found with extremely high levels of trans-resveratrol, cis- piceid, trans-piceid or total resveratrols in berry skins or leaves. In skins and leaves, rootstock cultivars had a higher content of total resveratrols, and the cultivated European type cultivars and their hybrids with V. labrusca had relatively low totals. There were no significant correlations of the amounts of total resveratrols or any individual resveratrol between berry skins and leaves. All 75 cultivars can be divided into four groups based on the composition of resveratrols and their concentration by principal component analysis. CONCLUSION: Resveratrol content of grape berries and leaves varied largely with their genetic background and usage. Rootstock cultivars had a higher content of total resveratrols than the other germplasm. Total resveratrols were lower in leaves than berry skins in most cultivars. Cis-piceid was the most abundant resveratrol in most cultivars, and trans-res and trans-pd were minor components.
Endophytes proved to exert multiple effects on host plants, including growth promotion, stress resistance. However, whether endophytes have a role in metabolites shaping of grape has not been fully understood. Eight endophytic fungal strains which originally isolated from grapevines were re-inoculated to field-grown grapevines in this study, and their effects on both leaves and berries of grapevines at maturity stage were assessed, with special focused on secondary metabolites and antioxidant activities. High-density inoculation of all these endophytic fungal strains modified the physio-chemical status of grapevine to different degrees. Fungal inoculations promoted the content of reducing sugar (RS), total flavonoids (TF), total phenols (TPh), trans-resveratrol (Res) and activities of phenylalanine ammonia-lyase (PAL), in both leaves and berries of grapevine. Inoculation of endophytic fungal strains, CXB-11 (Nigrospora sp.) and CXC-13 (Fusarium sp.) conferred greater promotion effects in grape metabolic re-shaping, compared to other used fungal strains. Additionally, inoculation of different strains of fungal endophytes led to establish different metabolites patterns of wine grape. The work implies the possibility of using endophytic fungi as fine-tuning regulator to shape the quality and character of wine grape.
Abstract: In this study, ten clones of Vitis vinifera Cabernet franc (not yet commercial) have been phenotyped on precocity, grape composition and assessment of wine quality made by micro vinification in 2008, 2009 and 2010. Additionally, two original criteria have been considered: concentration of 3-isobutyl-2-methoxypyrazine in grapes and wines (the green bell pepper flavor) and resistance of grapevines to downy mildew (Plasmopara viticola) by stilbene quantification upon infection. Precocity of veraison varied up to four days at veraison. Berry size and yield were highly variable among clones. However, these variables were not correlated. Tanins and anthocyanins varied among clones in grapes and wines. Variations in grape and wine IBMP were not significant. Some clones showed lower susceptibility for downy mildew on leaves. Lower susceptibility was linked to a higher production of stilbenic phytoalexins involved in downy mildew resistance mechanisms.
Grapevine leafroll disease (GLRD) is one of the most economically important virus diseases of grapevine (Vitis spp.) worldwide. In this study, we used high-throughput sequencing of cDNA libraries made from small RNAs (sRNAs) to compare profiles of sRNA populations recovered from own-rooted Merlot grapevines with and without GLRD symptoms. The data revealed the presence of sRNAs specific to Grapevine leafroll-associated virus 3, Hop stunt viroid (HpSVd), Grapevine yellow speckle viroid 1 (GYSVd-1) and Grapevine yellow speckle viroid 2 (GYSVd-2) in symptomatic grapevines and sRNAs specific only to HpSVd, GYSVd-1 and GYSVd-2 in nonsymptomatic grapevines. In addition to 135 previously identified conserved microRNAs in grapevine (Vvi-miRs), we identified 10 novel and several candidate Vvi-miRs in both symptomatic and nonsymptomatic grapevine leaves based on the cloning of miRNA star sequences. Quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) of selected conserved Vvi-miRs indicated that individual members of an miRNA family are differentially expressed in symptomatic and nonsymptomatic leaves. The high-resolution mapping of sRNAs specific to an ampelovirus and three viroids in mixed infections, the identification of novel Vvi-miRs and the modulation of certain conserved Vvi-miRs offers resources for the further elucidation of compatible host-pathogen interactions and for the provision of ecologically relevant information to better understand host-pathogen-environment interactions in a perennial fruit crop.
The aim of this paper was to find possible link between molecular and morphological similarities of 38 Hungarian white grape varieties. Three aspects of morphological and molecular similarity were assessed in the study: comparison of the ordered variety pairs, assessment of molecular and morphological mean similarity differences and separation of varieties into similar groups by divisive cluster analysis to define (DIANA). Molecular similarity was calculated from binary data based on allele sizes obtained in DNA analysis. DNA fingerprints were determined at 9 SSR loci recommended by the European GrapeGen06 project. Morphological similarity was calculated on the basis of quantitative morphological descriptors. Morphological and molecular similarity values were ordered and categorized after pairwise comparison. Overall correlation was found to be weak but case by case assessment of the variety pairs confirmed some coincidence of molecular and morphological similarity. General similarity position of each variety was characterized by Mean Similarity Index (MSI). It was calculated as the mean of n-1 pair similarity values of the variety concerned. Varieties were ordered and compared by the difference of the index. Five varieties had low morphological and high molecular MSI meaning that they share several SSR marker alleles with the others but seems relatively distinct according to the expression of their morphological traits. Divisive cluster analysis was carried out to find similar groups. Eight and twelve cluster solutions proved to be sufficient to distinct varieties. Morphological and molecular similarity groups partly coincided according to the results. Several clusters reflected parent offspring relations but molecular clustering gave more realistic results concerning pedigree.
We present a population model of the insect Scaphoideus titanus Ball, the leafhopper vector of Flavescence Dorée phytoplasma in Vitis vinifera L. The model accounted for the stage-dependent S. titanus life cycle rates and timing, and vineyard settings such as surface area, plant density, and sampling characteristics. The model parameters were estimated against 13 independent cases of population counting in both laboratory and field conditions, and returned a correlation coefficient in the range 86.4 to 99.1% with residuals in the range 3.5 to 26.3%. A statistical parametric analysis showed that the standard deviation of life cycle rates generally varied more than the one resulting from timing parameters. However, a stochastic sensitivity analysis showed that S. titanus dynamics were more susceptible to variations in timing than rate parameters. Analysis of scenarios of insecticide suppression efficiency and timing showed that S. titanus presence could be optimally controlled by a combination of suppression efficiency and timing. These results were instrumental to understand in which specific aspect of S. titanus life cycle could pest management operations be most effective to reduce S. titanus presence in vineyards, and possibly reduce the risk of Flavescence phytoplasma spread.
In this study, the adsorption/desorption characteristics of anthocyanins on five Amberlite resins (FPX-66, XAD-7HP, XAD-16N, XAD-1180 and XAD-761) were evaluated. FPX-66 and XAD-16N showed the highest adsorption and desorption capacities, and ratios for anthocyanins from muscadine pomace extract, while XAD-7HP had the lowest adsorption and desorption capacities, and ratios. Based on static adsorption and desorption tests three resins (FPX-66, XAD-16N and XAD-1180) were selected for adsorption kinetics and isotherms. The adsorption mechanism was better explained by the pseudo-first order kinetics for FPX-66 and XAD-16N; however, for XAD-1180 pseudo-second order kinetics was the most suitable model. The experimental data fitted best to Langmuir isotherm model for all the three resins. Dynamic testing was done on a column packed with FPX-66 resin and breakthrough volume was reached at 17 bed volumes of muscadine pomace water extract during adsorption. Three bed volumes of aqueous ethanol (70%) resulted in complete desorption. Resin adsorption resulted in a concentrated pomace extract that contained 13% (w/w) anthocyanins with no detectable sugars.
We present stilbenoid profiles of canes from sixteen grapevines. Fifteen stilbenoids were obtained through either isolation and structure identification using MS, NMR, and [α](D) or commercial standards. An HPLC-UV method for the simultaneous quantification of nine of these stilbenoids was developed and applied to canes of V. amurensis, V. arizonica, V. berlandieri, V. betulifolia, V. cinerea, V. x champini, V. x doaniana, V. labrusca, V. candicans (syn. V. mustangensis), V. riparia, V. rupestris, V. vinifera, Muscadinia rotundifolia, and a V. vinifera x M. rotundifolia hybrid. In these species, ampelopsin E, amurensin B, piceid, piceatannol, resveratrol, resveratroloside, ε-viniferin, ω-viniferin, and E-vitisin B were quantified, when found in sufficient amounts. Total concentrations ranged from ~2.2 to 19.5 g/kg dry weight. Additional stilbenoids, ampelopsin, 3,5,4'-trihydroxystilbene 2-C-glucoside, ampelopsin E, Z-trans-miyabenol C, E-trans-miyabenol C, scirpusin A, and Z-vitisin B, were identified, but not quantified. Our results indicate that canes, particularly those of non-vinifera species, have substantial quantities of valuable, health promoting stilbenoids.