Changes in grapevine DNA methylation and polyphenols content induced by solar ultraviolet-B radiation, water deficit and abscisic acid spray treatments.

Environment and crop management shape plant's phenotype. Argentinean high-altitude vineyards are characterized by elevated solar ultraviolet-B radiation (UVB) and water deficit (D) that enhance enological quality for red winemaking. These signals promote phenolics accumulation in leaves and berries, being the responses mediated by abscisic acid (ABA). DNA methylation is an epigenetic mechanism that regulates gene expression and may affect grapevine growth, development and acclimation, since methylation patterns are mitotically heritable. Berry skins low molecular weight polyphenols (LMWP) were characterized in field grown Vitis vinifera L. cv. Malbec plants exposed to contrasting UV-B, D, and ABA treatments during one season. The next season early fruit shoots were epigenetically (methylation-sensitive amplification polymorphism; MSAP) and biochemically (LMWP) characterized. Unstable epigenetic patterns and/or stochastic stress-induced methylation changes were observed. UV-B and D were the treatments that induced greater number of DNA methylation changes respect to Control; and UV-B promoted global hypermethylation of MSAP epiloci. Sequenced MSAP fragments associated with UV-B and ABA showed similarities with transcriptional regulators and ubiquitin ligases proteins activated by light. UV-B was associated with flavonols accumulation in berries and with hydroxycinnamic acids in the next season fruit shoots, suggesting that DNA methylation could regulate the LMWP accumulation and participate in acclimation mechanisms.

Marfil C ，Ibañez V ，Alonso R ，Varela A ，Bottini R ，Masuelli R ，Fontana A ，Berli F ... -  《-》

Malbec grape (Vitis vinifera L.) responses to the environment: Berry phenolics as influenced by solar UV-B, water deficit and sprayed abscisic acid.

High-altitude vineyards receive elevated solar ultraviolet-B (UV-B) levels so producing high quality berries for winemaking because of induction in the synthesis of phenolic compounds. Water deficit (D) after veraison, is a commonly used tool to regulate berry polyphenols concentration in red wine cultivars. Abscisic acid (ABA) plays a crucial role in the acclimation to environmental factors/signals (including UV-B and D). The aim of the present study was to evaluate independent and interactive effects of high-altitude solar UV-B, moderate water deficit and ABA applications on Vitis vinifera cv. Malbec berries. The experiment was conducted during two growing seasons with two treatments of UV-B (+UV-B and -UV-B), watering (+D and -D) and ABA (+ABA and -ABA), in a factorial design. Berry fresh weight, sugar content, fruit yield, phenolic compounds profile and antioxidant capacity (ORAC) were analyzed at harvest. Previous incidence of high UV-B prevented deleterious effects of water deficit, i.e. berry weight reduction and diminution of sugar accumulation. High UV-B increased total phenols (mainly astilbin, quercetin and kaempferol) and ORAC, irrespectively of the combination with other factors. Fruit yield was reduced by combining water deficit and high UV-B or water deficit and ABA. Two applications of ABA were enough to induced biochemical changes increasing total anthocyanins, especially those with higher antioxidant capacity.

Alonso R ，Berli FJ ，Fontana A ，Piccoli P ，Bottini R ... -  《-》

Solar UV-B and ABA are involved in phenol metabolism of Vitis vinifera L. increasing biosynthesis of berry skin polyphenols.

Berli FJ ，Fanzone M ，Piccoli P ，Bottini R ... -  《-》

Abscisic acid is involved in the response of grape (Vitis vinifera L.) cv. Malbec leaf tissues to ultraviolet-B radiation by enhancing ultraviolet-absorbing compounds, antioxidant enzymes and membrane sterols.

Berli FJ ，Moreno D ，Piccoli P ，Hespanhol-Viana L ，Silva MF ，Bressan-Smith R ，Cavagnaro JB ，Bottini R ... -  《-》

Acclimation mechanisms elicited by sprayed abscisic acid, solar UV-B and water deficit in leaf tissues of field-grown grapevines.

The independent and interactive effects of solar ultraviolet-B radiation (UV-B), moderate water deficit and sprayed abscisic acid (ABA) on leaves gas exchange and biochemical aspects of field-grown grapevines of the cv. Malbec were investigated in a high altitude vineyard (1450 m a.s.l.). Two UV-B treatments (ambient solar UV-B or reduced UV-B), two watering treatments (well watered or moderate water deficit) and two ABA treatments (no ABA and sprayed ABA) were given alone and combined in a factorial design. Gas exchange and photosynthesis were reduced by water deficit and highly impaired in the UV-B and water deficit combined treatment. UV-absorbing compounds were stimulated independently by UV-B. The monoterpenes α-pinene, 3-carene and terpinolene, and the sesquiterpene nerolidol were augmented by UV-B, water deficit or sprayed ABA. Levels of the triterpene squalene and the diterpene phytol were significantly higher in the treatment that combined UV-B, water deficit and ABA applications. Environment signals (solar UV-B and moderate water deficit) and sprayed ABA elicited mechanisms of acclimation by augmenting the content of terpenes with antioxidant and antifungal properties, thus enhancing the plant defensive mechanisms towards signals both biotic and abiotic.

Alonso R ，Berli FJ ，Bottini R ，Piccoli P ... -  《-》