Exogenous Abscisic Acid Can Remodel the Phenylpropanoid Network Under Elevated Temperature to Partially Sustain Anthocyanin Accumulation in Field-Grown ‘Malbec’ Grapes

Abstract

Climate change is advancing ripening and can impair phenolic maturity in grapes, compromisinganthocyanins and stilbenes that affect the wine color and stability. We tested whetherexogenous abscisic acid (ABA) mitigates warming-induced shifts in the phenylpropanoidpathway in the ’Malbec’ red wine grape variety. A factorial field experiment comparedcontrol temperature (−T) and elevated temperature (+T, +2.5 ◦C), with and without ABAsprays (three applications after veraison). Berry skin gene expression (ten flavonoid andstilbene genes) was monitored across ripening and summarized using time-course andAUC-based clustering. Anthocyanins were quantified in berry skins at harvest and in thecorresponding wines, and stilbenes were quantified in wines. Warming reduced MYBA1early in ripening and decreased anthocyanins and stilbenes overall. Meanwhile, ABAreinforced a late anthocyanin program under −T (MYBA1, UFGT, MYBC2-L3, F3′5′H),consistent with a shift toward the 3′,5′-hydroxylated/malvidin-type branch. Conversely,stilbenes remained suppressed under +T, with limited recovery under +T/+ABA. Timeintegratedexpression patterns and Spearman correlations consistently linked CHS2, F3′5′H,UFGT, MYBC2-L3, with variation in berry skin anthocyanins across treatments, while STSAUC tracked wine stilbenes. Overall, ABA partially buffered warming effects on ‘Malbec’color by reinforcing late anthocyanin regulation but did not prevent warming-drivendeclines in wine stilbenes.