(100-84) Foliar MeJA application induces endogenous phytohormonal responses that stimulate the antioxidant system in Vaccinium corymbosum under combined drought and aluminum stress.
Body of Abstract: The combination of aluminum (Al) stress and water deficit (Al+WD) has increased attention due to climate change. The highbush blueberry (Vaccinium corymbosum) is an important crop in southern Chile, being affected by this stress, reducing its productivity. The MeJA application activates plant resistance against Al+WD stress. This study aimed to investigate the role of MeJA in activating defense mechanisms in V. corymbosum plants subjected to Al+WD stress. Two cultivars, Star and Legacy, were exposed to control (low Al saturation, 80% field capacity), Al+WD (85% Al saturation, 50% field capacity), and Al+WD with different MeJA concentrations (10μM-50μM-100μM) in an Andisol. Al concentration, water potential (Ψw), antioxidant activity (AA), total polyphenols (TP), total phytohormones (TPH), superoxide dismutase activity (SOD), and gene expression of MATE and ALMT were determined in leaves and roots. Al+WD increased Al, being reduced by 60% with MeJA application compared to the control plants in both cultivars. MeJA application provoked an increase in Ψw under Al+WD. In the cultivar Legacy, Al+WD showed a 6-fold decrease in AA compared to the control, being recovered up to 70% after MeJA-50μM application. An increase in TP was observed with all doses of MeJA concerning the control. In cultivar Legacy, Al+WD decreased SOD activity by 30%, increasing with MeJA-50μM up to 3 times in both cultivars. TPH concentration and ALMT and MATE gene expression were increased with all MeJA doses in Legacy leaves and Star roots. Therefore, it is concluded that MeJA induces resistance mechanisms such as enzymatic and non-enzymatic antioxidant activity as well as the overexpression of ALMT and MATE genes. Acknowledgments: Fondecyt-1211856 (MR-D), Fondecyt-1201749 (CI-B), ANID/FONDAP/15130015 (MR-D), and ANID scholarship N°21202370.