Quantitative Proteomics Analysis of ABA- and GA 3 -Treated Malbec Berries Reveals Insights into H 2 O 2 Scavenging and Anthocyanin Dynamics.

Abscisic acid (ABA) and gibberellic acid (GA 3 ) are regulators of fruit color and sugar levels, and the application of these hormones is a common practice in commercial vineyards dedicated to the production of table grapes. However, the effects of exogenous ABA and GA 3 on wine cultivars remain unclear. We investigated the impact of ABA and GA 3 application on Malbec grapevine berries across three developmental stages. We found similar patterns of berry total anthocyanin accumulation induced by both treatments, closely associated with berry H 2 O 2 levels. Quantitative proteomics from berry skins revealed that ABA and GA 3 positively modulated antioxidant defense proteins, mitigating H 2 O 2 . Consequently, proteins involved in phenylpropanoid biosynthesis were downregulated, leading to decreased anthocyanin content at the almost ripe stage, particularly petunidin-3-G and peonidin-3-G. Additionally, we noted increased levels of the non-anthocyanins E-viniferin and quercetin in the treated berries, which may enhance H 2 O 2 scavenging at the almost ripe stage. Using a linear mixed-effects model, we found statistical significance for fixed effects including the berry H 2 O 2 and sugar contents, demonstrating their roles in anthocyanin accumulation. In conclusion, our findings suggest a common molecular mechanism by which ABA and GA 3 influence berry H 2 O 2 content, ultimately impacting anthocyanin dynamics during ripening.