Increasing the Phenolic Compound Content of Grapes by Preharvest Application of Abcisic Acid and a Combination of Methyl Jasmonate and Benzothiadiazole

Abstract

Benzothiadiazole (BTH) and methyl jasmonate (MeJ) have been described as exogenous elicitors of some plant defense compounds, polyphenols among them. Given that they activate different arrays of biochemical reactions to induce resistance, the objective of this study was to determine whether the joint application of BTH and MeJ to grape clusters affects the level of the main flavonoid compounds in grapes and in the resulting wines. The results are compared with those obtained when abscisic acid (ABA), a plant growth regulator involved in several physiological processes, was sprayed in the same vineyard. The results obtained indicated that, although the application of ABA increased the content of skin anthocyanins and tannins, these positive effects were not reflected in the wines made from these grapes. BTH+MeJ-treated grapes also presented higher anthocyanin and flavonol contents, and in this case, their wines presented better chromatic characteristics that the wine made from control grapes.

Improving phenolic and chromatic characteristics of Monastrell, Merlot and Syrah wines by using two elicitors

“…In the other two varieties, the treatments had no effect on grape size. Previous studies (Ruiz-García et al, 2013b) found that the application of BTH, MeJ, BTH+MeJ and ABA (abscisic acid) to Monastrell grapes had no effect on berry weight.…”

“…Anthocyanins are natural colorants present in the skin of red grapes, and they play a key role in the organoleptic characteristics of wines (Lesschaeve and Noble, 2005). The biosynthesis of these compounds can be influenced by exogenous elicitors such as ABA, BTH, and BTH/MeJ mixture (Ruiz-García et al, 2012;Ruiz-García et al, 2013a;Ruiz-García et al, 2013b).…”

“…There are many studies on the effect of preharvest application of MeJ and BTH to wine grapes. Such studies have pointed to increased levels of phenolic compounds in the treated grapes and corresponding wines for many varieties including Merlot (Iriti et al, 2004), Monastrell (Ruiz-García et al, 2012;Ruiz-García et al, 2013a;Ruiz-García et al, 2013b), Tempranillo (Portu et al, 2015;Portu et al, 2016), Groppello (Vitalini et al, 2014) and Syrah (Fernández-Marín et al, 2014). However, few researchers have studied the influence of preharvest treatments on several grape and wine varieties at the same time.…”

Effect of elicitors on the evolution of grape phenolic compounds during the ripening period

“…For example, Vitalini et al 29 investigated the aromatic profile of wines produced from BTH-treated Gropello grapes and observed an increase in total acetal and esters. Ruiz-García et al 1,30 also observed changes in the volatile composition of Monastrell grapes and wines when the grapes were treated with MeJ and BTH. It can be concluded, therefore, that elicitation is a good strategy for inducing the synthesis of different classes of bioactive secondary metabolites, although the efficacy of such treatment mainly depends on individual plant genetics, the nature of the elicitor and the dose used.…”

“…Our research group has focused its interest on the effect of the pre-harvest application (at veraison) of two elicitors, benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and methyl jasmonate (MeJ), on the phenolic and volatile compounds composition of grapes at harvest. 1,30,31 However, no studies have previously evaluated the evolution of the main grape phenolic compounds in the period from the time of application of the elicitors to harvesting. Neither has it been assessed whether vearison is the best moment for applying the elicitor or whether the application date could be optimised to obtain a maximum phenolic content at harvest.…”