Background and Aims In recent years, increasing summer temperature, coupled with reduced and erratic rainfall during the growing season, has induced accelerated fruit ripening in several regions, ...resulting in an undesirable increase in wine alcohol concentration. This study was designed to evaluate the impact of canopy and water management on grape sugar and flavonoid accumulation, with the goal of reducing wine alcohol concentration while conserving or enhancing the concentration of phenolic substances. Methods and Results In 2011 and 2012, two irrigation treatments (I - irrigated and DI - deficit irrigated) and two canopy heights (HC - high canopy and SC - short canopy) were applied in a Merlot vineyard. No interactions between treatments were observed, and thus independent results were obtained; DI berries had significantly higher sugar concentration (+5%) than that of I in both years and higher wine alcohol concentration only in 2012. Short canopy berries had lower sugar concentration (-4%) and lower wine alcohol (-8%) (only in 2011) than that of HC. Anthocyanins and tannins in berry and wine were increased by water deficit and not affected by severe trimming. Conclusions Deficit irrigation did not reduce berry sugar concentration and wine alcohol concentration but did enhance desirable wine attributes. Berry sugar concentration and alcohol concentration in wine were reduced by SC in one of the two seasons. Water deficit and severe trimming showed independent effects on berry composition. Significance of the Study Severe canopy reduction at early stages of ripening can reduce sugars without affecting the accumulation of anthocyanins in Merlot. Conversely, DI applied before veraison, despite promoting anthocyanins accumulation, may also increase berry sugar concentration at harvest.
In order to investigate the comparability of microsatellite profiles obtained in different laboratories, ten partners in seven countries analyzed 46 grape cultivars at six loci (VVMD5, VVMD7, VVMD27, ...VVS2, VrZAG62, and VrZAG79). No effort was made to standardize equipment or protocols. Although some partners obtained very similar results, in other cases different absolute allele sizes and, sometimes, different relative allele sizes were obtained. A strategy for data comparison by means of reference to the alleles detected in well-known cultivars was proposed. For each marker, each allele was designated by a code based on the name of the reference cultivar carrying that allele. Thirty-three cultivars, representing from 13 to 23 alleles per marker, were chosen as references. After the raw data obtained by the different partners were coded, more than 97% of the data were in agreement. Minor discrepancies were attributed to errors, suboptimal amplification and visualization, and misscoring of heterozygous versus homozygous allele pairs. We have shown that coded microsatellite data produced in different laboratories with different protocols and conditions can be compared, and that it is suitable for the identification and SSR allele characterization of cultivars. It is proposed that the six markers employed here, already widely used, be adopted as a minimal standard marker set for future grapevine cultivar analyses, and that additional cultivars be characterized by means of the coded reference alleles presented here. The complete database is available at http://www.genres.de/eccdb/vitis/. Cuttings of the 33 reference cultivars are available-on-request-from the Institut National de la Recherche Agronomique Vassal collection (didier.vares@ensam.inra.fr).
We report the sequences of 17 primer pairs of microsatellite loci, which we have cloned and sequenced from two genomic libraries of peach Prunus persica (L) Batsch 'Redhaven', enriched for AC/GT and ...AG/CT repeats respectively. For ten of these microsatellite loci we were able to demonstrate Mendelian inheritance in a segregating back-cross population; the remainder did not segregate. The polymorphism of the microsatellites was evaluated in a panel of ten peach genotypes, including true-to-type peaches, nectarines and one canning-peach. Fifteen microsatellites (88%) were polymorphic showing 2-4 alleles each. The mean heterozygosity, averaged over all loci, was 0.32 and significantly higher than that reported in the literature for isozymes and molecular markers, such as RFLPs and RAPDs. We have also assayed the cross-species transportability and found that ten microsatellite (59%) gave apparently correct amplification in all Prunus species surveyed, namely P. domestica (European plum), P. salicina (Japanese plum), P. armeniaca (apricot), P. dulcis (almond), P. persica var. vulgaris (peach), P. persica var. laevis (nectarine), P. avium (sweet cherry) and P. cerasus (sour cherry), with three of them also being amplified in Malus (apple). The remaining microsatellites gave less-extensive amplification. Because of their appreciable polymorphism and wide cross-species transportability, most of these new markers can be integrated into the linkage maps which are currently being constructed in peach, as well as in other stone fruit crops, such as almond, apricot, cherry and plum.
Eleven microsatellites isolated from grapevine (Vitis vinifera) were used to study the degree of conservation of these sequences across different Vitis species. Nine microsatellites were newly ...isolated, the remaining two (VVS2 and VVS5) came from the literature. A preliminary assay on the conservation of priming sites was carried out on 14 non-V. vinifera species, including relevant taxa for breeding. Parthenocissus quinquefolia was added as representative of a related genus. Cross-species amplification was obtained in 94% of the 176 genotype×locus tested combinations. Three microsatellite loci were then cloned and sequenced in ten species. The microsatellite repeat was found present in all cases. The repeat region was often longer in V. vinifera than in the other species. Furthermore the non-source species showed interruptions in the repeat. In spite of these constraints, which could reduce the polymorphism of microsatellites in non-source species, the results demonstrate the possibility of extending the use of microsatellite markers to wild germplasm and inter-specific hybrids. Point mutations have been found in microsatellite flanking regions and these variations have been used to investigate the genetic relationship among taxa. The Neighbor-joining tree that was obtained on the basis of ten nucleotide variations, showed that there is not a clear cut difference between American, Asian and European species and that the actual taxonomy which reflects the geographical distribution of species must most likely be revised. Moreover, in general, nucleotide variations which occur in microsatellite flanking regions provide new molecular tools for investigating the evolution of species.PUBLICATION ABSTRACT
Background and Aims
In recent years, increasing summer temperature, coupled with reduced and erratic rainfall during the growing season, has induced accelerated fruit ripening in several regions, ...resulting in an undesirable increase in wine alcohol concentration. This study was designed to evaluate the impact of canopy and water management on grape sugar and flavonoid accumulation, with the goal of reducing wine alcohol concentration while conserving or enhancing the concentration of phenolic substances.
Methods and Results
In 2011 and 2012, two irrigation treatments (I – irrigated and DI – deficit irrigated) and two canopy heights (HC – high canopy and SC – short canopy) were applied in a Merlot vineyard. No interactions between treatments were observed, and thus independent results were obtained; DI berries had significantly higher sugar concentration (+5%) than that of I in both years and higher wine alcohol concentration only in 2012. Short canopy berries had lower sugar concentration (−4%) and lower wine alcohol (−8%) (only in 2011) than that of HC. Anthocyanins and tannins in berry and wine were increased by water deficit and not affected by severe trimming.
Conclusions
Deficit irrigation did not reduce berry sugar concentration and wine alcohol concentration but did enhance desirable wine attributes. Berry sugar concentration and alcohol concentration in wine were reduced by SC in one of the two seasons. Water deficit and severe trimming showed independent effects on berry composition.
Significance of the Study
Severe canopy reduction at early stages of ripening can reduce sugars without affecting the accumulation of anthocyanins in Merlot. Conversely, DI applied before veraison, despite promoting anthocyanins accumulation, may also increase berry sugar concentration at harvest.
Structural genes of the phenyl-propanoid pathway which encode flavonoid 3'- and 3',5'-hydroxylases (F3'H and F3'5'H) have long been invoked to explain the biosynthesis of cyanidin- and ...delphinidin-based anthocyanin pigments in the so-called red cultivars of grapevine. The relative proportion of the two types of anthocyanins is largely under genetic control and determines the colour variation among red/purple/blue berry grape varieties and their corresponding wines.
Gene fragments of VvF3'H and VvF3'5'H, that were isolated from Vitis vinifera 'Cabernet Sauvignon' using degenerate primers designed on plant homologous genes, translated into 313 and 239 amino acid protein fragments, respectively, with up to 76% and 82% identity to plant CYP75 cytochrome P450 monooxygenases. Putative function was assigned on the basis of sequence homology, expression profiling and its correlation with metabolite accumulation at ten different ripening stages. At the onset of colour transition, transcriptional induction of VvF3'H and VvF3'5'H was temporally coordinated with the beginning of anthocyanin biosynthesis, the expression being 2-fold and 50-fold higher, respectively, in red berries versus green berries. The peak of VvF3'5'H expression was observed two weeks later concomitantly with the increase of the ratio of delphinidin-/cyanidin-derivatives. The analysis of structural genomics revealed that two copies of VvF3'H are physically linked on linkage group no. 17 and several copies of VvF3'5'H are tightly clustered and embedded into a segmental duplication on linkage group no. 6, unveiling a high complexity when compared to other plant flavonoid hydroxylase genes known so far, mostly in ornamentals.
We have shown that genes encoding flavonoid 3'- and 3',5'-hydroxylases are expressed in any tissues of the grape plant that accumulate flavonoids and, particularly, in skin of ripening red berries that synthesise mostly anthocyanins. The correlation between transcript profiles and the kinetics of accumulation of red/cyanidin- and blue/delphinidin-based anthocyanins indicated that VvF3'H and VvF3'5'H expression is consistent with the chromatic evolution of ripening bunches. Local physical maps constructed around the VvF3'H and VvF3'5'H loci should help facilitate the identification of the regulatory elements of each isoform and the future manipulation of grapevine and wine colour through agronomical, environmental and biotechnological tools.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
