Lipoic acid and 24-epibrassinolide collaborate synergistically to boost maize seedlings resilience to osmotic stress via modulating antioxidant and glyoxalase systems.

Abstract

Lipoic acid (LA) and 24-epibrassinolide (EBL) are versatile compounds that enhance plant stress tolerance by modulating cellular metabolism, maintaining ion balance, and boosting antioxidant enzyme activity. However, the combined effects of these two compounds in mitigating the adverse impacts of osmotic stress remain unclear. We investigated the effects of exogenous LA (12 µM), EBL (0.1 mg L^-1), and their combination (LA + EBL) on stress parameters (plant dry weight, total chlorophyll, leaf relative water content (LRWC)), oxidative stress markers (thiobarbituric acid-reactive substances, hydrogen peroxide, superoxide, and methylglyoxal), activities of antioxidant and glyoxalase system enzymes and the relative expression levels of the genes coding the enzymes related to these systems in maize seedlings under osmotic stress. The results indicated that exogenous application of LA and EBL combination reduced the level of oxidative stress markers and enhanced the stress parameters, ascorbate and glutathione levels, activities of enzymes acting antioxidant and glyoxalase systems, and their gene expression. The combination of LA and EBL was also found to stimulate gene expression levels related to the photosynthetic process and hormone biosynthesis. The findings of the current study highlighted the synergistic effects of combined LA and EBL in enhancing osmotic stress tolerance in maize seedlings. Overall, the combined application of LA and EBL found to have stronger effect than their individual applications in mitigating osmotic stress. The combined use of these compounds offers promising potential for developing drought-tolerant crops in the agricultural sector.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-025-01620-3.