Quantitative Proteomics Analysis of ABA- and GA₃-Treated Malbec Berries Reveals Insights into H₂O₂ Scavenging and...

Abscisic acid (ABA) and gibberellic acid (GA₃) 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 GA₃ on wine cultivars remain unclear. We investigated the impact of ABA and GA₃ 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 H₂O₂ levels. Quantitative proteomics from berry skins revealed that ABA and GA₃ positively modulated antioxidant defense proteins, mitigating H₂O₂. 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 H₂O₂ scavenging at the almost ripe stage. Using a linear mixed-effects model, we found statistical significance for fixed effects including the berry H₂O₂ and sugar contents, demonstrating their roles in anthocyanin accumulation. In conclusion, our findings suggest a common molecular mechanism by which ABA and GA₃ influence berry H₂O₂ content, ultimately impacting anthocyanin dynamics during ripening.