Methyl jasmonate application in grapes (Vitis labrusca L.) aiming to improve fruits phenolic compounds, flavonoids and stilbenes

Grapes (Vitis sp.) are considered a major source of phenolic compounds, such as flavonols, anthocyanins and stilbenes. Studies related to the beneficial effects exerted by these compounds on health, have encouraged researches that aimed to increase their concentration in fruits. Among the framework of possibilities to achieve these results, some plant growth regulators and its volatile ester methyl-jasmonate (MeJa), have shown promising results in many fruits. On this context, the present work aimed induce phenolic compounds, flavonoids and stilbenes on grapes (Vitis labrusca. L.), through pre harvest MeJa application. Treatment application optimization was performed on Concord and Isabel Precoce grapes on Brazilian south region on 2015 and 2016 harvest. Our best results were observed with MeJa application at 2 periods (véraison and 2 weeks before harvest). An increase of trans-resveratrol was observed specially for Isabel Precoce grapes in comparison with non-treated group, volatile compounds profile present biosynthetic pathways responsive to MeJa treatment on both harvests. Anthocyanin identification didn\'t display profile changes, being observed only differences between cultivars. Following, the treatment was evaluated on the same cultivars, on south (Bento Gonçalves, RS) and southeast (Caldas, MG) regions on 2017 and 2019 harvests. These grapes were processed and the juice evaluated regarding stilbenes content during storage (6 months), in comparison to non-treated grapes. In order to better understand the modifications promoted by MeJa treatment besides the target by our project, we performed a metabolomic study on grape and grape juice grown on south and southeast regions after MeJa treatment on 2017 harvest. In summary, we detect as strong markers stilbenes, anthocyanins, flavonoids and phenolic acids. The present study evidence the treatment with MeJa in inducing bioactive compounds, with potential on health promotion, since markers detected on grapes were detected even after thermal processing used for grape juice extraction. (AU)