Exogenous melatonin alleviates cadmium-induced inhibition of growth and photosynthesis through upregulating antioxidant defense system in strawberry

• Published in: South African journal of botany 2023-06, Vol.157, p.10-18
• Main Authors: Saqib, Muhammad, Shahzad, Umbreen, Zulfiqar, Faisal, Tiwari, Rahul Kumar, Lal, Milan Kumar, Naz, Safina, Jahan, Mohammad Shah, Awan, Zoia Arshad, El-Sheikh, Mohamed A., Altaf, Muhammad Ahsan
• Format: Article
• Language: English
• Subjects: agricultural productivity; anthocyanins; antioxidant activity; Antioxidant enzymes; biomass production; Cadmium; catalase; chlorophyll; gas exchange; Growth traits; homeostasis; hydrogen peroxide; leaves; malondialdehyde; Melatonin; oxidative stress; peroxidase; Photosynthesis; phytotoxicity; secondary metabolites; seedlings; strawberries; superoxide dismutase
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2023.03.039

Contamination by heavy metals has severely hampered agricultural productivity across the world. Cadmium (Cd) is one of the most dangerous heavy metals to plants. Melatonin (ME), a stress-relief hormone, has been extensively utilized to reduce phytotoxicity caused by heavy metals. In this work, we examined how ME reduced Cd damage in strawberry seedlings. The results revealed that Cd stress dramatically reduced growth characteristics (fresh and dry weight, root and shoot length), leaf gas exchange elements, and pigments content (chlorophyll a and chlorophyll b) in strawberry seedlings. In contrast, ME application efficiently enhanced growth and biomass production, increased net photosynthetic rate, and improved pigments molecules in strawberry seedling under Cd toxicity. Cadmium treatment effectively improved the level of malondialdehyde (MDA) and hydrogen peroxide (H2O2), whereas ME strictly counterbalanced these oxidative stress markers. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were dominantly increased by ME. Additionally, ME supplementation significantly improved secondary metabolites (phenols, anthocyanin, and flavonoids) content, and these metabolites potentially restricted excess H2O2 accumulation. In conclusion, our results revealed that ME might help to reduce Cd-induced phytotoxicity in strawberry seedlings by increasing growth, photosynthesis, redox homeostasis, and secondary metabolites. [Display omitted] •Melatonin enhanced cadmium stress tolerance in strawberry plants.•Melatonin stimulates antioxidant defense system in strawberry seedling under cadmium toxicity.•Melatonin increased photosynthesis apparatus in cadmium-stressed strawberry plants.•Melatonin as a supplement regulates defense mechanism in strawberry under cadmium stress.