Methyl jasmonate application in grape (Vitis labrusca) aiming enhance phenolic compounds (flavonoids and stilbenes)

Abstract

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 research that aimed to increase their concentration in fruits. Among the framework of possibilities to achieve these results, some plant growth regulators such as jasmonic acid and its volatile ester methyl-jasmonate (MJ), have shown promising results in many fruits. It has been demonstrated that jasmonates are effective inducers of the expression of phenylalanine ammonia lyase (PAL) and stilbene synthase (ES) that are directly related to phenolic compounds synthesis. In this context, this study aims to increase the content of phenolic compounds, flavonoids and stilbenes in grapes (Vitis labrusca), through the application of MJ in the pre-harvest period. It will be evaluated grapes from Concord and Isabel Precoce cultivars grown in the south (Bento Gonçalves, RS, altitude 671 meters) and southeast (Caldas, MG, altitude 1131 meters) after treatment with MJ and compare the results to non-treated fruit (control group) as the experimental design of randomized blocks containing 10 plants per block, each plant a repeat. Environmental factors will be followed (climate data) as well cultural practices that impact the quality (fertilization, pruning, etc.). It will be evaluated in berries the MJ levels, the contents of sugars and organic acids, phenolic compounds, flavonoids, tannins and stilbenes. In order to evaluate possible quality changes and levels of other metabolites that may be formed or whose content increases due to the application of the hormone, we will evaluate the profile of volatile and non-volatile metabolites. It will be produced a juice from treated and non-treated grapes and evaluated, the same analyses described above for the grapes. The sensory analysis will be done on these grape juices with a non-trained volunteer's panel. The results are going to be analyzed according the statistical design proposed. (AU)