Phytomelatonin: Recent advances and future prospects

Abstract

Melatonin (MEL) has been revealed as a phylogenetically conserved molecule with a ubiquitous distribution from primitive photosynthetic bacteria to higher plants, including algae and fungi. Since MEL is implicated in numerous plant developmental processes and stress responses, the exploration of its functions in plant has become a rapidly progressing field with the new paradigm of involvement in plants growth and development. The pleiotropic involvement of MEL in regulating the transcripts of numerous genes confirms its vital involvement as a multi‐regulatory molecule that architects many aspects of plant development. However, the cumulative research in plants is still preliminary and fragmentary in terms of its established functions compared to what is known about MEL physiology in animals. This supports the need for a comprehensive review that summarizes the new aspects pertaining to its functional role in photosynthesis, phytohormonal interactions under stress, cellular redox signaling, along with other regulatory roles in plant immunity, phytoremediation, and plant microbial interactions. The present review covers the latest advances on the mechanistic roles of phytomelatonin. While phytomelatonin is a sovereign plant growth regulator that can interact with the functions of other plant growth regulators or hormones, its qualifications as a complete phytohormone are still to be established. This review also showcases the yet to be identified potentials of phytomelatonin that will surely encourage the plant scientists to uncover new functional aspects of phytomelatonin in plant growth and development, subsequently improving its status as a potential new phytohormone.

MKP1 reduces neuroinflammation via inhibiting endoplasmic reticulum stress and mitochondrial dysfunction

“…In this study, we found that inflammation-induced oxidative stress altered the mitochondrial membrane, reducing mitochondrial potential and opening the mPTP (Q. Kanwar, Yu, & Zhou, 2018). This mitochondrial functional and structural damage was accompanied by mitochondrial apoptosis in microglia.…”

“…Excessive mitochondrial fission causes the uneven distribution of mitochondrial DNA into daughter mitochondria, leading to the inability of mitochondria to produce sufficient ATP (Bittremieux et al, ; T. Chen et al, ). In this study, we found that inflammation‐induced oxidative stress altered the mitochondrial membrane, reducing mitochondrial potential and opening the mPTP (Q. Chen et al, ; Kanwar, Yu, & Zhou, ). This mitochondrial functional and structural damage was accompanied by mitochondrial apoptosis in microglia.…”

Melatonin‐deficient rice plants show a common semidwarf phenotype either dependent or independent of brassinosteroid biosynthesis

“…In marked contrast to the snat2 rice, neither decreased melatonin nor the small‐leaf phenotype have been observed in Arabidopsis snat2 knockout mutant, albeit SNAT enzyme activity is comparable to Arabidopsis SNAT1 in vitro (data not shown), indicating an obviously different functional role of the SNAT2 isogene among plant species. Our findings greatly improve our understanding of the function of plant melatonin, which will be used as a valuable phenotypic marker for future studies to dissect the role of melatonin in many melatonin‐deficient or ‐signaling pathway mutants in plants, especially rice …”

Melatonin delays leaf senescence of Chinese flowering cabbage by suppressing ABFs‐mediated abscisic acid biosynthesis and chlorophyll degradation

“…Increasing evidence demonstrates that melatonin acts synergistically or antagonistically with other plant hormones including auxin, CTK, GA, ABA, ethylene, and JA during biological processes, mainly in stress responses . Under high salinity stress, melatonin promoted cucumber seed germination by reducing ABA accumulation achieved by downregulating ABA biosynthetic genes and upregulating ABA catabolic genes .…”

“…It was discovered in the pineal gland of cows in 1958 and subsequently in plants in 1995 . In plants, melatonin stimulates growth and development and acts as a signaling molecule associated with plant defense response to diverse biotic and abiotic stresses . Moreover, melatonin is a potent scavenger of a variety of reactive oxygen/nitrogen species (ROS/RNS) and organic radicals, and thus protects cells and tissues from oxidative damage .…”