Exogenous melatonin mitigates the adverse effects of drought stress in strawberry by upregulating the antioxidant defense system

Strawberry (Fragaria pound ananassa Duch.) is one of the most popular fruits in the world. Environmental stresses have a significant impact on the strawberry's growth and development. The most significant environmental stressor is drought, which has a negative effect on strawberry's production. This present research aimed to examine the protective role of melatonin (MT, 100 mM) on strawberry plants subjected to drought stress. The current results showed that drought stress signifcantly decreased growth, gas exchange parameters, and photosynthetic pigments content in strawberry. In contrast, MT application remarkably improved strawberry growth, gas exchange elements, and pigments concentration in strawberry leaves under drought stress. In addition, MT supplementation significantly reduced the levels of malondialdehyde (MDA), hydrogen peroxide (H2O2) and electrolyte leakage (EL). Further, MT pretreated strawberry plants effectively increased the antioxidant enzyme [Ascorbate peroxidase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX)] activity and non-enzymatic antioxidant [Ascorbate (AsA) and glutathione (GSH)] activity when the plants were exposed to drought stress. In conclusion, our results suggested MT application significantly improved soluble sugar accumulation, and photosynthetic apparatus, which may reduce oxidative stress biomarkers production. Finally, MT application increased the drought stress tolerance of strawberry seedlings.(c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.