Developmental and genetic mechanisms underlying seedlessness in grapevine somatic variants

Retrotransposons, particularly of the Ty-Copia and Ty-Gypsy superfamilies, represent the most abundant and widespread transposons in many plant genomes. Grapevine is no exception and it is clear that these mobile elements have played a major role in the evolution of Vitaceae genomes. While speculation abounds around the possible role of transposons in plant genomes, outside of the rather obvious involvement of retrotransposition in fueling genome expansion, there is little clarity of the actual role these elements have in both developing new genetic variation and in modulating epigenetic responses within genomes to changing climate. To this end we have been exploring de-novo assembled Sauvignon blanc and Pinot noir genomes with a view to catalogue retrotransposon loci to determine the structural intactness and thus age of insertion variation across a small number of clonal linages of these 2 varietals in an attempt to identify ‘live’ TE loci.

Wine regions are getting warmer as average temperatures continue raising affecting grape growth, berry composition and wine production. Berry quality was evaluated in plants of Vitis vinifera cv Syrah grafted on two rootstocks, Paulsen (PL1103) and SO4, and grown under two salinity concentrations (LS:0.7dS/m and HS:2.5dSm-1) in combination with two irrigation regimes (HW:133% and CW:100%), being the seasonal water application 483mm (control, 100%). Spectrophotometer measurements from berry skin during veraison and harvest stages and from “young” wine samples, were indicative of the stressors effect and the mediation of the rootstocks. At veraison (i) total phenolics content were high under LSHW (0.7dSm-1 and high water conditions) for SO4 and PL1103.

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Non-saccharomyces yeasts play a crucial role in fermentation, producing a variety of secondary metabolites and enzymes that contribute to aromatic and sensory complexity compared to saccharomyces yeasts. It is crucial to understand and control the dynamics of non-saccharomyces yeasts to produce distinctive and high-quality fermented beverages.

ine nitrogen deficiency can negatively influence the aroma profile and ageing potential of white wines. Canopy management can alter vine microclimate, affect the nitrogen availability and influence the response of leaf senescence. Increasing the nitrogen availability to vines can increase the Yeast Assimilable Nitrogen (YAN) levels in harvested fruit and wine. Studies show that foliar nitrogen and sulphur applications at véraison, on low YAN Sauvignon blanc grapes have an effect on the level of amino acids (Jreij et al. 2009) and on S-containing compounds such as glutathione and thiols (Lacroux et al. 2008), which in turn can influence the formation of major volatiles and the aroma profile of the wine.