Genetic and evolutionary dissection of melatonin response signaling facilitates the regulation of plant growth and stress responses

Abstract

The expansion of gene families during evolution could generate functional diversity among their members to regulate plant growth and development. Melatonin, a phylogenetically ancient molecule, is vital for many aspects of a plant's life. Understanding the functional diversity of the molecular players involved in melatonin biosynthesis, signaling, and metabolism will facilitate the regulation of plant phenotypes. However, the molecular mechanism of melatonin response signaling elements in regulating this network still has many challenges. Here, we provide an in‐depth analysis of the functional diversity and evolution of molecular components in melatonin signaling pathway. Genetic analysis of multiple mutants in plant species will shed light on the role of gene families in melatonin regulatory pathways. Phylogenetic analysis of these genes was performed, which will facilitate the identification of melatonin‐related genes for future study. Based on the abovementioned signal networks, the mechanism of these genes was summarized to provide reference for studying the regulatory mechanism of melatonin in plant phenotypes. We hope that this work will facilitate melatonin research in higher plants and finely tuned spatio‐temporal regulation of melatonin signaling.

Melatonin as a key regulator in seed germination under abiotic stress

“…76,77,281,282 Several enzymes are involved in MEL biosynthesis and metabolism (see Figure 1) and the functional characterization of genes encoding those enzymes relating to MEL biosynthesis and metabolism showed a diverse role of MEL in regulating plant growth and SG. 282 For instance, the ectopic expression of SNAT gene in rice increased seed width and length by regulating the gene expression of GRAIN INCOMPLETE FILLING-1 (GIF1) and GRAIN WIDTH-2 (GW2) and MEL accumulation in seeds. 283 Likewise, overexpression of VvSNAT gene in Arabidopsis resulted in higher SG rate and root and shoot length associated with better ROS scavenging and higher MEL accumulation.…”

“…The regulatory role of exogenously applied MEL in mediating SG under abiotic stresses is subjected to the MEL dose dependency, stress exposure time and seed quality 76,77,281,282 . Several enzymes are involved in MEL biosynthesis and metabolism (see Figure 1) and the functional characterization of genes encoding those enzymes relating to MEL biosynthesis and metabolism showed a diverse role of MEL in regulating plant growth and SG 282 .…”

Priming Potato Plants with Melatonin Protects Stolon Formation under Delayed Salt Stress by Maintaining the Photochemical Function of Photosystem II, Ionic Homeostasis and Activating the Antioxidant System

“…In plants, melatonin was discovered only in 1995 [ 11 , 13 ]. Melatonin is a multi-functional molecule [ 17 , 18 , 19 ]. Both melatonin itself and its metabolic products (cyclic 3-hydroxymelatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, N1-acetyl-5-methoxykynuramine, 6-hydroxymelatonin and 2-hydroxymelatonin) act as effective antioxidants, reducing the content of ROS or reactive nitrogen species (RNS), which leads to a decrease in the intensity of lipid peroxidation [ 11 , 20 , 21 ].…”

Unraveling the regulatory role of MYC2 on ASMT gene expression in wheat: Implications for melatonin biosynthesis and drought tolerance

“…Melatonin acts as a signaling molecule, affecting gene expression through interactions with specific melatonin receptors and modulating the activity of transcription factors involved in stress‐responsive pathways. For instance, NAC transcription factor genes are involved in the resistance to plant abiotic stress regulated by melatonin (Gao et al, 2023). As an antioxidant and activator of the plant's enzymatic and non‐enzymatic antioxidant system, it also plays an essential role in redox homeostasis in plant cells under stressful conditions (Rehaman et al, 2021; Tiwari et al, 2021).…”

“…The biosynthesis of melatonin in plants involves four enzymatic steps catalyzed by tryptophan decarboxylase (TDC), tryptamine 5‐hydroxylase (T5H), serotonin N‐acetyltransferase (SNAT), N‐acetylserotonin methyltransferase (ASMT), and caffeic acid O‐methyltransferase (COMT; Back, 2021). Gene expression studies have revealed that the expression of melatonin biosynthesis genes is induced under abiotic stress conditions, leading to increased melatonin production (Gao et al, 2023). Through gene knockout or overexpression experiments, researchers have demonstrated the impact of these genes on drought tolerance.…”