ABA and Solar UV-B radiation effects on phenolics profile of Vitis vinifera L. cv. Malbec berry skins

BERLI F.; FANZONE M.; PICCOLI P.; ALONSO R.; BOTTINI R.

Tarragona

Congreso; XX International Plant Growth Substances Association (IPGSA) Meeting; 2010

IPGSA

In Mendoza, Argentina, vineyards are located between 500 and 1,500 m above the sea level. The most reputed for high quality winemaking are those placed at the higher altitudes, because of the increased flavor of the wines obtained. One of the differences between the sites is the solar ultraviolet-B radiation (UV-B) received by the vines, which increased with the altitude. We previously demonstrated (Berli et al. 2010, Plant Cell & Environ.) that ABA participates in the signal transduction of leaf tissues defense activation towards UV-B by triggering the biosynthesis of phenolics that filter the harmful radiation or act as antioxidants by scavenging reactive oxygen species (ROS). The objective of the present work was to study across the berry development of Vitis vinifera L. cv. Malbec the role of ABA on the phenolic profile in berry skins under the effect of solar UV-B combined with ABA application in a vineyard at 1,500 m. A factorial design with two levels of UV-B and two levels of ABA was performed. UV-B treatments consisting in solar UV-B exclusion (-UV-B) and solar UV-B (+UV-B) commenced 15 days before flowering and lasted until harvest. ABA was administrated from 45 days after flowering (DAF) until harvest in weekly sprays of 1 mM ABA (+ABA) or H2O (-ABA). Berries were sampled every 20 days starting at 50 DAF and the endogenous ABA and phenolics in the skins were assessed by GC-MS and HPLC-DAD, respectively. ABA augmented in all treatments from 50 to 92 DAF and then decreased to very low levels. However, ABA levels at 92 DAF (20 days after veraison) were 110.3% higher in the combined +UV-B/+ABA-treatment than in the -UV-B/-ABA-treatment. The single UV-B and ABA application treatments increased the levels of the anthocyanidins malvidin, delphinidin, peonidin, petunidin and cyanidin, either non-acylated, acetylated and coumaroylated. The combination of +UV-B/+ABA had 29.7% more total anthocyanins than -UV-B/-ABA at 126 DAF (harvest-time). UV-B increased total low molecular weight non-anthocyanin phenols, total flavonols, total dihydroflavonols, total flavanols, and gallic, protocatechuic, vanillic acids. ABA augmented quercetin-3-glucoside, quercetin-3-rhamnoside, kaempferol-3-glucoside, unknown dihydroflavonols, gallic acid and protocatechuic acid, without affecting the total subgroups contents. +UV-B/+ABA had 40.9% more total low molecular weight non-anthocyanin phenols than -UV-B/-ABA at 126 DAF. In conclusion, the UV-B and ABA effects on the phenolics profile of berry skins are additive and ABA does not replace the UV-B effects on phenolic metabolism.