Lactic acid bacteria priming of antioxidant defense systems mitigates oxidative damage and preserves postharvest quality in tomato under drought stress

This study investigated foliar-applied Lactic Acid Bacteria (LAB) as a biostimulant to enhance postharvest resilience and quality of tomato (Solanum lycopersicum L.) fruit under drought stress. A randomized greenhouse experiment was conducted with four treatments: optimal irrigation, drought stress, and LAB applications combined with both irrigation regimes. Upon reaching physiological maturity, harvested fruits were stored at 7°C for a 20-day period, with evaluations of physicochemical and biochemical markers at regular intervals. Results demonstrated LAB application as a biochemical primer, significantly mitigating drought-induced physiological deterioration by stabilizing fruit pH and attenuating tissue softening. Notably, LAB treatments elicited a robust systemic antioxidant response, increasing total phenolics, flavonoids, and carotenoids. This was accompanied by upregulation of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). Moreover, a significant reduction in malondialdehyde (MDA) levels indicated that LAB effectively preserves cellular membrane integrity by suppressing lipid peroxidation. These findings suggest that foliar LAB intervention acts as a potent metabolic modulator, optimizing the antioxidant defense machinery and extending the postharvest shelf-life of tomatoes under environmental stress. This research provides a sustainable and 'green' framework for enhancing the economic value and nutritional longevity of horticultural crops amid escalating climate challenges.