Improving stilbenes in vitis Labrusca L. Grapes through methyl jasmonate applications

Abstract

Context and purpose of the study – Grapes (Vitis sp.) are considered a major source of phenolic compounds such as flavonols, anthocyanins and stilbenes. Studies related to the beneficial effects of these compounds on health have encouraged research aimed at increasing their concentration in fruits. On this behalf, several plant growth regulators such as jasmonic acid and its volatile ester, methyl-jasmonate (MeJa), have demonstrated promising results in many fruits. However, Brazilian subtropical climate might interfere on treatment response. The present study aims to evaluate the application of MeJa in the pre-harvest period in Concord and Isabel Precoce grapes (Vitis labrusca L.).

Material and methods – Grapes cultivated in Brazil’s southern region (Bento Gonçalves, RS, altitude: 671 meters) receive a MeJa solution into different periods during ripening. Grapes were harvested, analyzed and the results compared to non-treated fruit (control group). Edaphoclimatic conditions and cultural practices were monitored (climate data, soil, fertilization, pruning, etc.). Anthocyanins and stilbenes were quantified by analytical reversed-phase liquid chromatography (Agilent Technologies, model 1260 Infinity) equipped with a DAD.

Results – The results obtained after a 2-years study has provided evidence that MeJa application is an eco-friendly means to enhance compounds such anthocyanin and stilbenes in Vitis labrusca L. grapes, grown even in subtropical climate. The effectiveness of MeJa application seems to be related to phenological state in the period of application. Best results were obtained with two applications: during véraison and approximately two weeks before harvest. Our results suggest that MeJa treatment enhances trans-resveratrol and piceid contents when grapes are treated in these conditions. Further studies are being conducted in other Brazilian regions with the objective of better understanding the behavior of Vitis labrusca L. grapes towards MeJa treatment in different edaphoclimatic conditions.