Pinot Noir grape colour related phenolics as affected by leaf removal treatments in the Vipava Valley

Light-induced Variation in Phenolic Compounds in Cabernet Sauvignon Grapes (Vitis vinifera L.) Involves Extensive Transcriptome Reprogramming of Biosynthetic Enzymes, Transcription Factors, and Phytohormonal Regulators

“…The present study shows that the concentration of total HCAs was significantly increased in the sunlight exposure berries in comparison with the control berries at both véraison and harvest in all the three experimental seasons, except for berries from LR-PS and LR-AV treatments, in which the level of HCAs was slightly higher during véraison while lower at the harvest stage compared with the control in both the 2011 and 2012 seasons ( Figure 2A and Supplementary Table S4). The results obtained in our study are inconsistent with a previous study conducted on Pinot Noir, which showed that the concentration of HCAs throughout maturation was effectively enhanced by leaf removal at berry set but slight influenced by leaf removal at véraison (Lemut et al, 2011). Of the three classes of flavonoids, flavan-3-ols are present in the greatest proportion in grapes, followed by anthocyanins, with flavonols being present at relatively low levels (Downey et al, 2004).…”

“…For instance, leaf removal at berry set increased skin anthocyanins in grapes of Merlot, Cabernet Sauvignon and Pinot noir (Lemut et al, 2011; Kotseridis et al, 2012), and pre-bloom leaf removal also substantially increased anthocyanin concentration in Barbera, Lambrusco salamino, Graciano, and Carignan grapes when compared with no leaf removal (Poni et al, 2009; Tardaguila et al, 2010). However, another exposure study indicated that no significant differences among treatments were observed in anthocyanin levels in Nebbiolo grapes at harvest, although leaf removal caused a temporary acceleration of anthocyanin accumulation throughout ripening (Chorti et al, 2010).…”

“…In recent years, a considerable amount of effort has been devoted to investigating the impact of cluster sunlight exposure treatments during specific stages of berry development and ripening on the detailed phenolic profiles as well as the expression of related structural and regulatory genes in different grape varieties (Matus et al, 2009; Chorti et al, 2010; Lemut et al, 2011; Kotseridis et al, 2012; Lee and Skinkis, 2013; Matsuyama et al, 2014; Wu et al, 2014; Friedel et al, 2015). For instance, the expression of flavonol synthase 1 ( VviFLS1 , also known as VviFLS4 ) and its specific transcriptional activator VviMYB12 (also named VviMYBF1 ) was drastically increased following leaf removal treatment, which ultimately resulted in the quickly increased flavonol synthesis (Matus et al, 2009).…”

Identification of a defoliation severity threshold for changing fruitset, bunch morphology and fruit composition in Pinot Noir

“…The lack of the effect could be attributed to a detrimental influence of excessive bunch exposure and high temperature on anthocyanins biosynthesis (Bergqvist et al 2001). There are reports, however, that five to six leaves removed at flowering in two different locations in Washington (Lee and Skinkis 2013) and six leaves removed at berry set and veraison in two different locations in Slovenia (Sternad Lemut et al 2011) increased anthocyanins in Pinot Noir. Also, some other red cultivars (Merlot, Cabernet Sauvignon and Ciliegiolo) responded to early defoliation by increasing the concentration of anthocyanins in the grape juice (Kotseridis et al 2012, Palliotti et al 2012.…”

Impact of Leaf Removal, Applied Before and After Flowering, on Anthocyanin, Tannin, and Methoxypyrazine Concentrations in ‘Merlot’ (Vitis vinifera L.) Grapes and Wines

“…4,11 Moreover this technique can improve grape composition 4,12 by increasing total soluble solids (TSS), 4,11,13 anthocyanins, and other polyphenols; 4,11,14 possibly by improving the leaf area-to-yield ratio. However, this results have not always been consistent between climates, vintages, and cultivars.…”