Mechanistic review of melatonin metabolism and signaling pathways in plants: Biosynthesis, regulation, and roles under abiotic stress
Muhammad Ikram,
Muhammad Mehran,
Haseeb ur Rehman,
Shafi Ullah,
Muhammad Zeeshan Mola Bakhsh,
Maryam Tahira,
Muhammad Faizan Khurram Maqsood,
Abdul Rauf,
Sahrish Ghafar,
Kamran Haider,
Ömer Konuşkan,
Çağdaş Can Toprak,
Zeki Erden,
Ayman El Sabagh
Affiliations
Muhammad Ikram
Department of Agronomy Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University Multan, Pakistan; MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China; Corresponding author.
Muhammad Mehran
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan 430070, China
Haseeb ur Rehman
Department of Agronomy Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University Multan, Pakistan; Corresponding author.
Shafi Ullah
MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
Muhammad Zeeshan Mola Bakhsh
Key Laboratory of Crop Genetics improvement, Ministry of Education, Wuhan, Hubei 430070, China
Maryam Tahira
National Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, Hubei 430070, China
Muhammad Faizan Khurram Maqsood
National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops/Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture and Rural Affairs, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China
Abdul Rauf
National Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, Hubei 430070, China
Sahrish Ghafar
Department of Chemistry, University of Education Lahore, (Multan Campus), Pakistan
Kamran Haider
Biocontrol Laboratory, Department of Entomology, University of Agriculture Faisalabad, Pakistan
Ömer Konuşkan
Department of Field Crops, Faculty of Agriculture, Mustafa Kemal University, Hatay, Turkey
Çağdaş Can Toprak
Department of Field Crops, Faculty of Agriculture, Siirt University, Siirt Turkey
Zeki Erden
Department of Field Crops, Faculty of Agriculture, Siirt University, Siirt Turkey
Ayman El Sabagh
Department of Field Crops, Faculty of Agriculture, Siirt University, Siirt Turkey
Melatonin, a multifunctional biomolecule found in animals and plants, is critical in regulating various physiological processes. In plants, melatonin biosynthesis primarily originates from tryptophan through multiple enzymatic steps, finely controlled by different environmental and endogenous factors. This review synthesizes current knowledge on melatonin biosynthesis, production levels, and signaling mechanisms, focusing on its role in plant stress responses. Research shows that melatonin mitigates abiotic stresses such as drought, salinity, and temperature extremes by enhancing antioxidant systems, scavenging reactive oxygen species, and modulating ion homeostasis. Additionally, melatonin signaling, which may involve the mitogen-activated protein kinase (MAPK) cascade and potentially the Cand2 receptor (though its role remains debated), is essential for promoting plant growth and enhancing stress tolerance. This review also examines the potential of targeting specific enzymes, such as tryptamine 5-hydroxylase (T5H), to create melatonin knockout mutants, offering new insights into the regulatory networks of melatonin-mediated stress responses. The review concludes by identifying future research directions, particularly in understanding the complex cross-talk within melatonin signaling pathways and the debated role of Cand2 in plant resilience.
