# Melatonin: A Dual Protector of Pepper Plants Under Drought Stress via Antioxidant Defence and Glyoxalase-Mediated Cell Detoxification

## TL;DR

Melatonin helps pepper plants survive drought by boosting antioxidants and detox systems.

## Contribution

This study reveals melatonin's dual role in enhancing drought tolerance via antioxidant defense and MG detoxification.

## Key findings

- Drought-tolerant pepper plants with higher melatonin levels showed better MG detox and less membrane damage.
- Exogenous melatonin reduced MG accumulation and boosted antioxidant and glyoxalase enzyme activity.
- Melatonin activates both antioxidant defenses and the glyoxalase pathway to improve drought tolerance in peppers.

## Abstract

Although the antioxidant role of melatonin in stress mitigation is well established, its multifunctionality may support plant tolerance to drought through additional mechanisms. This study aimed to evaluate melatonin’s contribution to both antioxidant defence and methylglyoxal (MG) detoxification—a harmful compound that disrupts cellular balance under drought stress. The glyoxalase pathway, which is aided by glutathione, plays a pivotal role in MG detoxification. Therefore, we examined the impact of both endogenous and exogenous melatonin on this system. Two pepper genotypes differing in drought tolerance and endogenous melatonin levels were exposed to 12 days of drought following a 5 µM melatonin treatment. The drought-tolerant genotype, characterized by higher levels of endogenous melatonin, exhibited more efficient MG detoxification through increased glutathione and glyoxalase activities, reduced membrane damage and enhanced antioxidant capacity. Exogenous melatonin further mitigated the effects of drought by reducing MG accumulation and stimulating antioxidant and glyoxalase enzymes. Overall, both endogenous and applied melatonin enhances drought tolerance in pepper by activating antioxidant defences and the glyoxalase pathway.