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Malakar P, Gupta SK, Chattopadhyay D. Role of plant neurotransmitters in salt stress: A critical review. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 211:108601. [PMID: 38696867 DOI: 10.1016/j.plaphy.2024.108601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 03/22/2024] [Accepted: 04/03/2024] [Indexed: 05/04/2024]
Abstract
Neurotransmitters are naturally found in many plants, but the molecular processes that govern their actions still need to be better understood. Acetylcholine, γ-Aminobutyric acid, histamine, melatonin, serotonin, and glutamate are the most common neurotransmitters in animals, and they all play a part in the development and information processing. It is worth noting that all these chemicals have been found in plants. Although much emphasis has been placed on understanding how neurotransmitters regulate mood and behaviour in humans, little is known about how they regulate plant growth and development. In this article, the information was reviewed and updated considering current thinking on neurotransmitter signaling in plants' metabolism, growth, development, salt tolerance, and the associated avenues for underlying research. The goal of this study is to advance neurotransmitter signaling research in plant biology, especially in the area of salt stress physiology.
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Affiliation(s)
- Paheli Malakar
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
| | - Santosh K Gupta
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
| | - Debasis Chattopadhyay
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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Kołodziejczyk I, Kaźmierczak A. Melatonin - This is important to know. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 919:170871. [PMID: 38340815 DOI: 10.1016/j.scitotenv.2024.170871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 02/07/2024] [Accepted: 02/07/2024] [Indexed: 02/12/2024]
Abstract
MEL (N-acetyl-5-methoxytryptamine) is a well-known natural compound that controls cellular processes in both plants and animals and is primarily found in plants as a neurohormone. Its roles have been described very broadly, from its antioxidant function related to the photoperiod and determination of seasonal rhythms to its role as a signalling molecule, imitating the action of plant hormones (or even being classified as a prohormone). MEL positively affects the yield and survival of plants by increasing their tolerance to unfavourable biotic and abiotic conditions, which makes MEL widely applicable in ecological farming as a stimulant of growth and development. Thus, it is called a phytobiostimulator. In this review, we discuss the genesis of MEL functions, the presence of MEL at the cellular level and its effects on gene expression and plant development, which can ensure the survival of plants under the conditions they encounter. Moreover, we consider the future application possibilities of MEL in agriculture.
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Affiliation(s)
- Izabela Kołodziejczyk
- Department of Geobotany and Plant Ecology, Institute of Ecology and Environmental Protection, University of Lodz, Lodz 90-236, Banacha 12/16, 90-237, Poland
| | - Andrzej Kaźmierczak
- Department of Cytophysiology, Institute of Experimental Biology Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland.
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Jiang M, Song Y, Yang R, Zheng C, Zheng Y, Zhang H, Li S, Tan Y, Huang J, Shu Q, Li R. Melatonin activates the OsbZIP79-OsABI5 module that orchestrates nitrogen and ROS homeostasis to alleviate nitrogen-limitation stress in rice. PLANT COMMUNICATIONS 2023; 4:100674. [PMID: 37598294 PMCID: PMC10721462 DOI: 10.1016/j.xplc.2023.100674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/09/2023] [Accepted: 08/16/2023] [Indexed: 08/21/2023]
Abstract
Melatonin (Mel) has previously been reported to effectively alleviate nitrogen-limitation (N-L) stress and thus increase nitrogen-use efficiency (NUE) in several plants, but the underlying mechanism remains obscure. Here, we revealed that OsbZIP79 (BASIC LEUCINE ZIPPER 79) is transcriptionally activated under N-L conditions, and its expression is further enhanced by exogenous Mel. By the combined use of omics, genetics, and biological techniques, we revealed that the OsbZIP79-OsABI5 (ABSCISIC ACID INSENSITIVE 5) module stimulated regulation of reactive oxygen species (ROS) homeostasis and the uptake and metabolism of nitrogen under conditions of indoor nitrogen limitation (1/16 normal level). OsbZIP79 activated the transcription of OsABI5, and OsABI5 then bound to the promoters of target genes, including genes involved in ROS homeostasis and nitrogen metabolism, activating their transcription. This module was also indispensable for upregulation of several other genes involved in abscisic acid catabolism, nitrogen uptake, and assimilation under N-L and Mel treatment, although these genes were not directly transactivated by OsABI5. Field experiments demonstrated that Mel significantly improved rice growth under low nitrogen (L-N, half the normal level) by the same mechanism revealed in the nitrogen-limitation study. Mel application produced a 28.6% yield increase under L-N and thus similar increases in NUE. Also, two OsbZIP79-overexpression lines grown in L-N field plots had significantly higher NUE (+13.7% and +21.2%) than their wild types. Together, our data show that an OsbZIP79-OsABI5 module regulates the rice response to N insufficiency (N limitation or low N), which is important for increasing NUE in rice production.
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Affiliation(s)
- Meng Jiang
- Hainan Institute, Zhejiang University, Yazhou Bay Sci-Tech City, Sanya, China; National Key Laboratory of Rice Breeding and Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm, The Advanced Seed Institute, Zhejiang University, Hangzhou, China
| | - Yue Song
- Hainan Institute, Zhejiang University, Yazhou Bay Sci-Tech City, Sanya, China; National Key Laboratory of Rice Breeding and Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm, The Advanced Seed Institute, Zhejiang University, Hangzhou, China
| | - Ruifang Yang
- Crop Breeding and Cultivation Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Chenfan Zheng
- Hainan Institute, Zhejiang University, Yazhou Bay Sci-Tech City, Sanya, China; National Key Laboratory of Rice Breeding and Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm, The Advanced Seed Institute, Zhejiang University, Hangzhou, China
| | - Yunchao Zheng
- School of Life Sciences, Westlake University, Hangzhou, China
| | - Huali Zhang
- State Key Laboratory of Rice Breeding and Biology and Chinese National Center for Rice Improvement, China National Rice Research Institute, Hangzhou, China
| | - Shan Li
- National Key Laboratory of Rice Breeding and Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm, The Advanced Seed Institute, Zhejiang University, Hangzhou, China
| | - Yuanyuan Tan
- National Key Laboratory of Rice Breeding and Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm, The Advanced Seed Institute, Zhejiang University, Hangzhou, China
| | - Jianzhong Huang
- Hainan Institute, Zhejiang University, Yazhou Bay Sci-Tech City, Sanya, China
| | - Qingyao Shu
- Hainan Institute, Zhejiang University, Yazhou Bay Sci-Tech City, Sanya, China; National Key Laboratory of Rice Breeding and Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm, The Advanced Seed Institute, Zhejiang University, Hangzhou, China.
| | - Ruiqing Li
- College of Agronomy, Anhui Agricultural University, Hefei, China.
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Wei H, Wang J, Wang Q, He W, Liao S, Huang J, Hu W, Tang M, Chen H. Role of melatonin in enhancing arbuscular mycorrhizal symbiosis and mitigating cold stress in perennial ryegrass ( Lolium perenne L.). Front Microbiol 2023; 14:1123632. [PMID: 37283923 PMCID: PMC10239815 DOI: 10.3389/fmicb.2023.1123632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 05/04/2023] [Indexed: 06/08/2023] Open
Abstract
Melatonin is a biomolecule that affects plant development and is involved in protecting plants from environmental stress. However, the mechanisms of melatonin's impact on arbuscular mycorrhizal (AM) symbiosis and cold tolerance in plants are still unclear. In this research, AM fungi inoculation and exogenous melatonin (MT) were applied to perennial ryegrass (Lolium perenne L.) seedlings alone or in combination to investigate their effect on cold tolerance. The study was conducted in two parts. The initial trial examined two variables, AM inoculation, and cold stress, to investigate the involvement of the AM fungus Rhizophagus irregularis in endogenous melatonin accumulation and the transcriptional levels of its synthesis genes in the root system of perennial ryegrass under cold stress. The subsequent trial was designed as a three-factor analysis, encompassing AM inoculation, cold stress, and melatonin application, to explore the effects of exogenous melatonin application on plant growth, AM symbiosis, antioxidant activity, and protective molecules in perennial ryegrass subjected to cold stress. The results of the study showed that compared to non-mycorrhizal (NM) plants, cold stress promoted an increase in the accumulation of melatonin in the AM-colonized counterparts. Acetylserotonin methyltransferase (ASMT) catalyzed the final enzymatic reaction in melatonin production. Melatonin accumulation was associated with the level of expression of the genes, LpASMT1 and LpASMT3. Treatment with melatonin can improve the colonization of AM fungi in plants. Simultaneous utilization of AM inoculation and melatonin treatment enhanced the growth, antioxidant activity, and phenylalanine ammonia-lyase (PAL) activity, while simultaneously reducing polyphenol oxidase (PPO) activity and altering osmotic regulation in the roots. These effects are expected to aid in the mitigation of cold stress in Lolium perenne. Overall, melatonin treatment would help Lolium perenne to improve growth by promoting AM symbiosis, improving the accumulation of protective molecules, and triggering in antioxidant activity under cold stress.
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Aghdam MS, Mukherjee S, Flores FB, Arnao MB, Luo Z, Corpas FJ. Functions of Melatonin during Postharvest of Horticultural Crops. PLANT & CELL PHYSIOLOGY 2023; 63:1764-1786. [PMID: 34910215 DOI: 10.1093/pcp/pcab175] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 10/11/2021] [Accepted: 12/14/2021] [Indexed: 05/14/2023]
Abstract
Melatonin, a tryptophan-derived molecule, is endogenously generated in animal, plant, fungal and prokaryotic cells. Given its antioxidant properties, it is involved in a myriad of signaling functions associated with various aspects of plant growth and development. In higher plants, melatonin (Mel) interacts with plant regulators such as phytohormones, as well as reactive oxygen and nitrogen species including hydrogen peroxide (H2O2), nitric oxide (NO) and hydrogen sulfide (H2S). It shows great potential as a biotechnological tool to alleviate biotic and abiotic stress, to delay senescence and to conserve the sensory and nutritional quality of postharvest horticultural products which are of considerable economic importance worldwide. This review provides a comprehensive overview of the biochemistry of Mel, whose endogenous induction and exogenous application can play an important biotechnological role in enhancing the marketability and hence earnings from postharvest horticultural crops.
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Affiliation(s)
- Morteza Soleimani Aghdam
- Department of Horticultural Science, Imam Khomeini International University, Qazvin 34148-96818, Iran
| | - Soumya Mukherjee
- Department of Botany, Jangipur College, University of Kalyani, West Bengal 742213, India
| | - Francisco Borja Flores
- Department of Stress Biology and Plant Pathology, CEBAS-CSIC, Espinardo-Murcia 30100, Spain
| | - Marino B Arnao
- Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, Murcia 30100, Spain
| | - Zisheng Luo
- College of Biosystems Engineering and Food Science, Key Laboratory of Agro-Products Postharvest Handling Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
| | - Francisco J Corpas
- Department of Biochemistry, Cell and Molecular Biology of Plants, Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Estación Experimental del Zaidín, CSIC, C/Profesor Albareda, 1, Granada 18008, Spain
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Zhu B, Zheng S, Fan W, Zhang M, Xia Z, Chen X, Zhao A. Ectopic overexpression of mulberry MnT5H2 enhances melatonin production and salt tolerance in tobacco. FRONTIERS IN PLANT SCIENCE 2022; 13:1061141. [PMID: 36507424 PMCID: PMC9733638 DOI: 10.3389/fpls.2022.1061141] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
Soil salinization severely inhibits plant growth and has become one of the major limiting factors for global agricultural production. Melatonin (N-acetyl-5-methoxytryptamine) plays an important role in regulating plant growth and development and in responding to abiotic stresses. Tryptamine-5-hydroxylase (T5H) is an enzyme essential for the biosynthesis of melatonin in plants. Previous studies have identified the gene MnT5H for melatonin synthesis in mulberry (Morus notabilis), but the role of this gene in response to salinity stress in mulberry is remain unclear. In this study, we ectopically overexpressed MnT5H2 in tobacco (Nicotiana tabacum L.) and treated it with NaCl solutions. Compared to wild-type (WT), melatonin content was significantly increased in the overexpression-MnT5H2 tobacco. Under salt stress, the expression of NtCAT, NtSOD, and NtERD10C and activity of catalase (CAT), peroxidase (POD), and the content of proline (Pro) in the transgenic lines were significantly higher than that in WT. The Malondialdehyde (MDA) content in transgenic tobacco was significantly lower than that of WT. Furthermore, transgenic tobacco seedlings exhibited faster growth in media with NaCl. This study reveals the changes of melatonin and related substance content in MnT5H2-overexpressing tobacco ultimately lead to improve the salt tolerance of transgenic tobacco, and also provides a new target gene for breeding plant resistance to salt.
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Affiliation(s)
- Baozhong Zhu
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Sha Zheng
- School of Electronic Information and Artificial Intelligence, Shaanxi University of Science & Technology, Xi'an, China
| | - Wei Fan
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Meirong Zhang
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Zhongqiang Xia
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Xuefei Chen
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Aichun Zhao
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
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Liu Y, Wang X, Lv H, Cao M, Li Y, Yuan X, Zhang X, Guo YD, Zhang N. Anabolism and signaling pathways of phytomelatonin. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5801-5817. [PMID: 35430630 DOI: 10.1093/jxb/erac158] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/13/2022] [Indexed: 06/14/2023]
Abstract
Phytomelatonin is a small multifunctional molecule found ubiquitously in plants, which plays an important role in plant growth, development, and biotic and abiotic stress responses. The classical biosynthetic and metabolic pathways of phytomelatonin have been elucidated, and uncovering alternative pathways has deepened our understanding of phytomelatonin synthesis. Phytomelatonin functions mainly via two pathways. In the direct pathway, phytomelatonin mediates the stress-induced reactive oxygen species burst through its strong antioxidant capacity. In the indirect pathway, phytomelatonin acts as a signal to activate signaling cascades and crosstalk with other plant hormones. The phytomelatonin receptor PMTR1/CAND2 was discovered in 2018, which enhanced our understanding of phytomelatonin function. This review summarizes the classical and potential pathways involved in phytomelatonin synthesis and metabolism. To elucidate the functions of phytomelatonin, we focus on the crosstalk between phytomelatonin and other phytohormones. We propose two models to explain how PMTR1 transmits the phytomelatonin signal through the G protein and MAPK cascade. This review will facilitate the identification of additional signaling molecules that function downstream of the phytomelatonin signaling pathway, thus improving our understanding of phytomelatonin signal transmission.
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Affiliation(s)
- Ying Liu
- College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Xiaoyun Wang
- College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Hongmei Lv
- College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Meng Cao
- College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Yongchong Li
- College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Xiaowei Yuan
- Huasheng Agriculture Co. Ltd, Qingzhou, Shandong, 262500, China
| | - Xichun Zhang
- School of Plant Science and Technology, Beijing Agricultural University, Beijing, 102206, China
| | - Yang-Dong Guo
- College of Horticulture, China Agricultural University, Beijing, 100193, China
- Sanya Institute of China Agricultural University, Sanya, 572000, China
| | - Na Zhang
- College of Horticulture, China Agricultural University, Beijing, 100193, China
- Sanya Institute of China Agricultural University, Sanya, 572000, China
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Wang Z, Mu Y, Hao X, Yang J, Zhang D, Jin Z, Pei Y. H 2S aids osmotic stress resistance by S-sulfhydration of melatonin production-related enzymes in Arabidopsis thaliana. PLANT CELL REPORTS 2022; 41:365-376. [PMID: 34812898 DOI: 10.1007/s00299-021-02813-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
Hydrogen sulfide closed Arabidopsis thaliana stomata by increasing the transcription of melatonin-producing enzymes and the post-translational modification levels to combat osmotic stress. Hydrogen sulfide (H2S) and melatonin (MEL) reportedly have similar functions in many aspects of plant growth, development and stress response. They regulate stomatal movement and enhance drought resistance. However, their physiological relationship is not well understood. Here, their crosstalk involved in osmotic stress resistance in Arabidopsis thaliana was studied. Exogenous H2S and MEL closed stomata under normal or osmotic stress conditions and increased the relative water contents of plants under osmotic stress conditions. At the same time, exogenous H2S and MEL responded to osmotic stress by increasing the content of proline and soluble sugar, and reducing malondialdehyde (MDA) content and relative conductivity. Using mutants in the MEL-associated production of serotonin N-acetyltransferase (snat), caffeic acid O-methyltransferase (comt1) and N-acetylserotonin methyltransferase (asmt), we determined that H2S was partially dependent on MEL to close stomata. Additionally, the overexpression of ASMT promoted stomatal closure. Exogenous H2S increased the transcription levels of SNAT, ASMT and COMT1. Furthermore, exogenous H2S treatments increased the endogenous MEL content significantly. At the post-translational level, H2S sulfhydrated the SNAT and ASMT, but not COMT1, enzymes associated with MEL production. Thus, H2S appeared to promote stomatal closure in response to osmotic stress by increasing the transcription levels of MEL synthesis-related genes and the sulfhydryl modification of the encoded enzymes. These results increased our understanding of H2S and MEL functions and interactions under osmotic stress conditions.
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Affiliation(s)
- Zhiqing Wang
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, 030006, Shanxi Province, China
| | - Yao Mu
- Institute of Space Information, Space engineering University, Beijing, 101416, China
| | - Xuefeng Hao
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, 030006, Shanxi Province, China
- Department of Biology, Taiyuan Normal University, Jinzhong, 030619, Shanxi Province, China
| | - Jinbao Yang
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, 030006, Shanxi Province, China
| | - Daixuan Zhang
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, 030006, Shanxi Province, China
| | - Zhuping Jin
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, 030006, Shanxi Province, China.
| | - Yanxi Pei
- School of Life Science and Shanxi Key Laboratory for Research and Development of Regional Plants, Shanxi University, Taiyuan, 030006, Shanxi Province, China.
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Mannino G, Pernici C, Serio G, Gentile C, Bertea CM. Melatonin and Phytomelatonin: Chemistry, Biosynthesis, Metabolism, Distribution and Bioactivity in Plants and Animals-An Overview. Int J Mol Sci 2021; 22:ijms22189996. [PMID: 34576159 PMCID: PMC8469784 DOI: 10.3390/ijms22189996] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 12/21/2022] Open
Abstract
Melatonin is a ubiquitous indolamine, largely investigated for its key role in the regulation of several physiological processes in both animals and plants. In the last century, it was reported that this molecule may be produced in high concentrations by several species belonging to the plant kingdom and stored in specialized tissues. In this review, the main information related to the chemistry of melatonin and its metabolism has been summarized. Furthermore, the biosynthetic pathway characteristics of animal and plant cells have been compared, and the main differences between the two systems highlighted. Additionally, in order to investigate the distribution of this indolamine in the plant kingdom, distribution cluster analysis was performed using a database composed by 47 previously published articles reporting the content of melatonin in different plant families, species and tissues. Finally, the potential pharmacological and biostimulant benefits derived from the administration of exogenous melatonin on animals or plants via the intake of dietary supplements or the application of biostimulant formulation have been largely discussed.
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Affiliation(s)
- Giuseppe Mannino
- Department of Life Sciences and Systems Biology, Plant Physiology Unit, University of Turin, Via Quarello 15/A, 10135 Turin, Italy; (G.M.); (C.P.)
| | - Carlo Pernici
- Department of Life Sciences and Systems Biology, Plant Physiology Unit, University of Turin, Via Quarello 15/A, 10135 Turin, Italy; (G.M.); (C.P.)
| | - Graziella Serio
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy;
| | - Carla Gentile
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy;
- Correspondence: (C.G.); (C.M.B.); Tel.: +39-091-2389-7423 (C.G.); +39-011-670-6361 (C.M.B.)
| | - Cinzia M. Bertea
- Department of Life Sciences and Systems Biology, Plant Physiology Unit, University of Turin, Via Quarello 15/A, 10135 Turin, Italy; (G.M.); (C.P.)
- Correspondence: (C.G.); (C.M.B.); Tel.: +39-091-2389-7423 (C.G.); +39-011-670-6361 (C.M.B.)
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Chen W, Zhang J, Zheng S, Wang Z, Xu C, Zhang Q, Wu J, Lou H. Metabolite profiling and transcriptome analyses reveal novel regulatory mechanisms of melatonin biosynthesis in hickory. HORTICULTURE RESEARCH 2021; 8:196. [PMID: 34465767 PMCID: PMC8408178 DOI: 10.1038/s41438-021-00631-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/20/2021] [Accepted: 06/06/2021] [Indexed: 05/08/2023]
Abstract
Studies have shown that melatonin regulates the expression of various elements in the biosynthesis and catabolism of plant hormones. In contrast, the effects of these different plant hormones on the biosynthesis and metabolism of melatonin and their underlying molecular mechanisms are still unclear. In this study, the melatonin biosynthesis pathway was proposed from constructed metabolomic and transcriptomic libraries from hickory (Carya cathayensis Sarg.) nuts. The candidate pathway genes were further identified by phylogenetic analysis, amino-acid sequence alignment, and subcellular localization. Notably, most of the transcription factor-related genes coexpressed with melatonin pathway genes were hormone-responsive genes. Furthermore, dual-luciferase and yeast one-hybrid assays revealed that CcEIN3 (response to ethylene) and CcAZF2 (response to abscisic acid) could activate melatonin biosynthesis pathway genes, a tryptophan decarboxylase coding gene (CcTDC1) and an N-acetylserotonin methyltransferase coding gene (CcASMT1), by directly binding to their promoters, respectively. Our results provide a molecular basis for the characterization of novel melatonin biosynthesis regulatory mechanisms and demonstrate for the first time that abscisic acid and ethylene can regulate melatonin biosynthesis.
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Affiliation(s)
- Wenchao Chen
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China
| | - Jiaqi Zhang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China
| | - Shan Zheng
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China
| | - Zhanqi Wang
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, 313000, Huzhou, China
| | - Chuanmei Xu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China
| | - Qixiang Zhang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China
| | - Jiasheng Wu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China
| | - Heqiang Lou
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300, Hangzhou, Zhejiang, China.
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Zheng S, Zhu Y, Liu C, Fan W, Xiang Z, Zhao A. Genome-wide identification and characterization of genes involved in melatonin biosynthesis in Morus notabilis (wild mulberry). PHYTOCHEMISTRY 2021; 189:112819. [PMID: 34087504 DOI: 10.1016/j.phytochem.2021.112819] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/19/2021] [Accepted: 05/16/2021] [Indexed: 06/12/2023]
Abstract
Melatonin is recognized as an important regulator for human health and widely distributed in many plant species, including mulberry (Morus L.). Previous studies suggested mulberry contains high melatonin content, but the molecular mechanisms underlying melatonin biosynthesis in mulberry remain unclear. Here, 37 genes involved in melatonin biosynthesis were identified in mulberry genome, including a tryptophan decarboxylase gene (MnTDC), seven tryptophan 5-hydroxylase genes (MnT5Hs), six serotonin N-acetyltransferase genes (MnSNATs), 20 N-acetylserotonin methyltransferase genes (MnASMTs) and three caffeic acid 3-O-methyltransferase genes (MnCOMTs). Expression analysis showed that MnTDC, MnT5H2, MnSNAT5, MnASMT12 and MnCOMT1 from these genes had highest expression levels within their corresponding families. In vitro enzymatic assays indicated that MnTDC, MnT5H2, MnSNAT5, MnASMT12 and MnCOMT1 play important roles in melatonin biosynthesis. Multiple different pathways for melatonin biosynthesis in mulberry were discovered. In addition, mulberry ASMT showed distinct roles with those of ASTMs in Arabidopsis and rice. The class I ASMT, MnASMT12, and the class III ASMT, MnASMT20, catalyzed the conversion of N-acetylserotonin to melatonin and serotonin to 5-methoxytryptamine. Furthermore, the class II ASMT, MnASMT16, only catalyzed the conversion of N-acetylserotonin to melatonin. This study improved our knowledge on melatonin biosynthesis in mulberry and expands the repertoire of melatonin biosynthesis pathways in plants.
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Affiliation(s)
- Sha Zheng
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China
| | - Yingxue Zhu
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China
| | - Changying Liu
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, Chengdu University, Chengdu, 610106, China
| | - Wei Fan
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China
| | - Zhonghuai Xiang
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China
| | - Aichun Zhao
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400716, China.
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12
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Negri S, Commisso M, Avesani L, Guzzo F. The case of tryptamine and serotonin in plants: a mysterious precursor for an illustrious metabolite. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5336-5355. [PMID: 34009335 DOI: 10.1093/jxb/erab220] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/13/2021] [Indexed: 06/12/2023]
Abstract
Indolamines are tryptophan-derived specialized metabolites belonging to the huge and ubiquitous indole alkaloids group. Serotonin and melatonin are the best-characterized members of this family, given their many hormonal and physiological roles in animals. Following their discovery in plants, the study of plant indolamines has flourished and their involvement in important processes, including stress responses, growth and development, and reproduction, has been proposed, leading to their classification as a new category of phytohormones. However, the complex indolamine puzzle is far from resolved, particularly the biological roles of tryptamine, the early serotonin precursor representing the central hub of many downstream indole alkaloids. Tryptophan decarboxylase, which catalyzes the synthesis of tryptamine, strictly regulates the flux of carbon and nitrogen from the tryptophan pool into the indolamine pathway. Furthermore, tryptamine accumulates to high levels in the reproductive organs of many plant species and therefore cannot be classed as a mere intermediate but rather as an end product with potentially important functions in fruits and seeds. This review summarizes current knowledge on the role of tryptamine and its close relative serotonin, emphasizing the need for a clear understanding of the functions of, and mutual relations between, these indolamines and their biosynthesis pathways in plants.
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Affiliation(s)
- Stefano Negri
- Department of Biotechnology, University of Verona, Strada Le Grazie, Verona, Italy
| | - Mauro Commisso
- Department of Biotechnology, University of Verona, Strada Le Grazie, Verona, Italy
| | - Linda Avesani
- Department of Biotechnology, University of Verona, Strada Le Grazie, Verona, Italy
| | - Flavia Guzzo
- Department of Biotechnology, University of Verona, Strada Le Grazie, Verona, Italy
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13
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Zhang Z, Zhang Y. Melatonin in plants: what we know and what we don’t. FOOD QUALITY AND SAFETY 2021. [DOI: 10.1093/fqsafe/fyab009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Melatonin is an endogenous micromolecular compound of indoleamine with multiple physiological functions in various organisms. In plants, melatonin is involved in growth and development, as well as in responses to biotic and abiotic stresses. Furthermore, melatonin functions in phytohormone-mediated signal transduction pathways. There are multiple melatonin biosynthesis pathways, and the melatonin content in plants is greatly affected by intrinsic genetic characteristics and external environmental factors. Although melatonin biosynthesis has been extensively studied in model plants, it remains uncharacterized in most plants. This article focuses on current knowledge on the biosynthesis, regulation and application of melatonin, particularly for fruit quality and preservation. In addition, it highlights the links between melatonin and other hormones, as well as future research directions.
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Inhibition of Rice Serotonin N-Acetyltransferases by MG149 Decreased Melatonin Synthesis in Rice Seedlings. Biomolecules 2021; 11:biom11050658. [PMID: 33946959 PMCID: PMC8145546 DOI: 10.3390/biom11050658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 11/17/2022] Open
Abstract
We examined the effects of two histone acetyltransferase (HAT) inhibitors on the activity of rice serotonin N-acetyltransferases (SNAT). Two rice recombinant SNAT isoenzymes (SNAT1 and SNAT2) were incubated in the presence of either MG149 or MB3, HAT inhibitors. MG149 significantly inhibited the SNAT enzymes in a dose-dependent manner, especially SNAT1, while SNAT2 was moderately inhibited. By contrast, MB3 had no effect on SNAT1 or SNAT2. The application of 100 μM MG149 to rice seedlings decreased melatonin by 1.6-fold compared to the control, whereas MB3 treatment did not alter the melatonin level. MG149 significantly decreased both melatonin and N-acetylserotonin when rice seedlings were challenged with cadmium, a potent elicitor of melatonin synthesis in rice. Although MG149 inhibited melatonin synthesis in rice seedlings, no melatonin deficiency-induced lamina angle decrease was observed due to the insufficient suppression of SNAT2, which is responsible for the lamina angle decrease in rice.
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Key Genes in the Melatonin Biosynthesis Pathway with Circadian Rhythm Are Associated with Various Abiotic Stresses. PLANTS 2021; 10:plants10010129. [PMID: 33435489 PMCID: PMC7827461 DOI: 10.3390/plants10010129] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 01/06/2021] [Indexed: 02/04/2023]
Abstract
Melatonin (N-acetyl-5-methoxytryptamine), a well-known animal hormone, is involved in several biological processes including circadian rhythm and the regulation of abiotic stress. A systematic understanding of the circadian regulation of melatonin biosynthesis-related genes has not been achieved in rice. In this study, key genes for all of the enzymes in the melatonin biosynthetic pathway that showed a peak of expression at night were identified by microarray data analysis and confirmed by qRT–PCR analysis. We further examined the expression patterns of the four genes under drought, salt, and cold stresses. The results showed that abiotic stresses, such as drought, salt, and cold, affected the expression patterns of melatonin biosynthetic genes. In addition, the circadian expression patterns of tryptophan decarboxylase (TDC), tryptamine 5-hydroxylase (T5H), and serotonin N-acetyltransferase (SNAT) genes in wild-type (WT) plants was damaged by the drought treatment under light and dark conditions. Conversely, N-acetylserotonin O-methyltransferase (ASMT) retained the circadian rhythm. The expression of ASMT was down-regulated by the rice gigantea (OsGI) mutation, suggesting the involvement of the melatonin biosynthetic pathway in the OsGI-mediated circadian regulation pathway. Taken together, our results provide clues to explain the relationship between circadian rhythms and abiotic stresses in the process of melatonin biosynthesis in rice.
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Back K. Melatonin metabolism, signaling and possible roles in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:376-391. [PMID: 32645752 DOI: 10.1111/tpj.14915] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 06/15/2020] [Accepted: 06/24/2020] [Indexed: 05/20/2023]
Abstract
Melatonin is a multifunctional biomolecule found in both animals and plants. In this review, the biosynthesis, levels, signaling, and possible roles of melatonin and its metabolites in plants is summarized. Tryptamine 5-hydroxylase (T5H), which catalyzes the conversion of tryptamine into serotonin, has been proposed as a target to create a melatonin knockout mutant presenting a lesion-mimic phenotype in rice. With a reduced anabolic capacity for melatonin biosynthesis and an increased catabolic capacity for melatonin metabolism, all plants generally maintain low melatonin levels. Some plants, including Arabidopsis and Nicotiana tabacum (tobacco), do not possess tryptophan decarboxylase (TDC), the first committed step enzyme required for melatonin biosynthesis. Major melatonin metabolites include cyclic 3-hydroxymelatonin (3-OHM) and 2-hydroxymelatonin (2-OHM). Other melatonin metabolites such as N1 -acetyl-N2 -formyl-5-methoxykynuramine (AFMK), N-acetyl-5-methoxykynuramine (AMK) and 5-methoxytryptamine (5-MT) are also produced when melatonin is applied to Oryza sativa (rice). The signaling pathways of melatonin and its metabolites act via the mitogen-activated protein kinase (MAPK) cascade, possibly with Cand2 acting as a melatonin receptor, although the integrity of Cand2 remains controversial. Melatonin mediates many important functions in growth stimulation and stress tolerance through its potent antioxidant activity and function in activating the MAPK cascade. The concentration distribution of melatonin metabolites appears to be species specific because corresponding enzymes such as M2H, M3H, catalases, indoleamine 2,3-dioxygenase (IDO) and N-acetylserotonin deacetylase (ASDAC) are differentially expressed among plant species and even among different tissues within species. Differential levels of melatonin and its metabolites can lead to differential physiological effects among plants when melatonin is either applied exogenously or overproduced through ectopic overexpression.
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Affiliation(s)
- Kyoungwhan Back
- Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea
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17
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Sami A, Shah FA, Abdullah M, Zhou X, Yan Y, Zhu Z, Zhou K. Melatonin mitigates cadmium and aluminium toxicity through modulation of antioxidant potential in Brassica napus L. PLANT BIOLOGY (STUTTGART, GERMANY) 2020; 22:679-690. [PMID: 32003103 DOI: 10.1111/plb.13093] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/21/2020] [Indexed: 05/03/2023]
Abstract
Melatonin has emerged as an essential molecule in plants, due to its role in defence against metal toxicity. Aluminium (Al) and cadmium (Cd) toxicity inhibit rapeseed seedling growth. In this study, we applied different doses of melatonin (50 and 100 µm) to alleviate Al (25 µm) and Cd (25 µm) stress in rapeseed seedlings. Results show that Al and Cd caused toxicity in rapeseed seedling, as evidenced by a decrease in height, biomass and antioxidant enzyme activity. Melatonin increased the expression of melatonin biosynthesis-related Brassica napus genes for caffeic acid O-methyl transferase (BnCOMT) under Al and Cd stress. The genes BnCOMT-1, BnCOMT-5 and BnCOMT-8 showed up-regulated expression, while BnCOMT-4 and BnCOMT-6 were down-regulated during incubation in water. Melatonin application increased the germination rate, shoot length, root length, fresh and dry weight of seedlings. Melatonin supplementation under Al and Cd stress increased superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, proline, chlorophyll and anthocyanin content, as well as photosynthesis rate. Both Cd and Al treatments significantly increased hydrogen peroxide and malondialdehyde levels in rapeseed seedlings, which were strictly counterbalanced by melatonin. Analysis of Cd and Al in different subcellular compartments showed that melatonin enhanced cell wall and soluble fractions, but reduced the vacuolar and organelle fractions in Al- and Cd-treated seedlings. These results suggest that melatonin-induced improvements in antioxidant potential, biomass, photosynthesis rate and successive Cd and Al sequestration play a pivotal role in plant tolerance to Al and Cd stress. This mechanism may have potential implications in safe food production.
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Affiliation(s)
- A Sami
- College of Agronomy, Anhui Agricultural University, Hefei, China
| | - F A Shah
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - M Abdullah
- School of Life Sciences, Anhui Agricultural University, Hefei, China
| | - X Zhou
- College of Agronomy, Anhui Agricultural University, Hefei, China
| | - Y Yan
- College of Agronomy, Anhui Agricultural University, Hefei, China
| | - Z Zhu
- College of Agronomy, Anhui Agricultural University, Hefei, China
| | - K Zhou
- College of Agronomy, Anhui Agricultural University, Hefei, China
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18
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Zhou Y, Liao L, Liu X, Liu B, Chen X, Guo Y, Huang C, Zhao Y, Zeng Z. Crystal structure of Oryza sativa TDC reveals the substrate specificity for TDC-mediated melatonin biosynthesis. J Adv Res 2020; 24:501-511. [PMID: 32595985 PMCID: PMC7306523 DOI: 10.1016/j.jare.2020.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 04/20/2020] [Accepted: 06/08/2020] [Indexed: 01/01/2023] Open
Abstract
Plant tryptophan decarboxylase (TDC) is a type II Pyridoxal-5'-phosphate-dependent decarboxylase (PLP_DC) that could be used as a target to genetically improve crops. However, lack of accurate structural information on plant TDC hampers the understanding of its decarboxylation mechanisms. In the present study, the crystal structures of Oryza sativa TDC (OsTDC) in its complexes with pyridoxal-5'-phosphate, tryptamine and serotonin were determined. The structures provide detailed interaction information between TDC and its substrates. The Y359 residue from the loop gate is a proton donor and forms a Lewis acid-base pair with serotonin/tryptamine, which is associated with product release. The H214 residue is responsible for PLP binding and proton transfer, and its proper interaction with Y359 is essential for OsTDC enzyme activity. The extra hydrogen bonds formed between the 5-hydroxyl group of serotonin and the backbone carboxyl groups of F104 and P105 explain the discrepancy between the catalytic activity of TDC in tryptophan and in 5-hydroxytryptophan. In addition, an evolutionary analysis revealed that type II PLP_DC originated from glutamic acid decarboxylase, potentially as an adaptive evolution of mechanism in organisms in extreme environments. This study is, to our knowledge, the first to present a detailed analysis of the crystal structure of OsTDC in these complexes. The information regarding the catalytic mechanism described here could facilitate the development of protocols to regulate melatonin levels and thereby contribute to crop improvement efforts to improve food security worldwide.
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Affiliation(s)
- Yuanze Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Lijing Liao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Xikai Liu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Biao Liu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Xinxin Chen
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Yan Guo
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Chuanlong Huang
- Jiangsu Key Laboratory of Bioactive Natural Product Research and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210014, China
| | - Yucheng Zhao
- Jiangsu Key Laboratory of Bioactive Natural Product Research and State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210014, China
| | - Zhixiong Zeng
- Shandong Provincial Key Laboratory of Microbial Engineering, College of Bioengineering, Qilu University of Technology, Jinan 250353, China
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Zhang X, Zhang H, Zhang H, Tang M. Exogenous Melatonin Application Enhances Rhizophagus irregularis Symbiosis and Induces the Antioxidant Response of Medicago truncatula Under Lead Stress. Front Microbiol 2020; 11:516. [PMID: 32351459 PMCID: PMC7174712 DOI: 10.3389/fmicb.2020.00516] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/10/2020] [Indexed: 12/20/2022] Open
Abstract
Melatonin is a new kind of plant growth regulator. The aim of this study was to figure out the effect of melatonin on arbuscular mycorrhizal (AM) symbiosis and heavy metal tolerance. A three-factor experiment was conducted to determine the effect of melatonin application on the growth, AM symbiosis, and stress tolerance of Medicago truncatula. A two-factor (AM inoculation and Pb stress) experiment was conducted to determine the effect of AM fungus on melatonin accumulation under Pb stress. AM plants under Pb stress had a higher melatonin accumulation than non-mycorrhizal (NM) plants under Pb stress. Acetylserotonin methyltransferase (ASMT) is the enzymatic reaction of the last step in melatonin synthesis. The accumulation of melatonin may be related to the expression of MtASMT. Melatonin application increased the relative expression of MtPT4 and AM colonization in AM plants. Melatonin application decreased Pb uptake with and without AM inoculation. Both melatonin application and AM inoculation improved M. truncatula growth and increased antioxidant response with Pb stress. These results indicated that melatonin application has positive effects on AM symbiosis and Pb stress tolerance under Pb stress. AM inoculation improve melatonin synthesis capacity under Pb stress. Melatonin application may improve AM plant growth by enhancing AM symbiosis, stimulating antioxidant response, and inhibiting Pb uptake.
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Affiliation(s)
- Xiangyu Zhang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Forestry, Northwest A&F University, Yangling, China
| | - Huijuan Zhang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Forestry, Northwest A&F University, Yangling, China
| | - Haoqiang Zhang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Forestry, Northwest A&F University, Yangling, China
| | - Ming Tang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Forestry, Northwest A&F University, Yangling, China.,State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
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20
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Lee K, Back K. Melatonin-deficient rice plants show a common semidwarf phenotype either dependent or independent of brassinosteroid biosynthesis. J Pineal Res 2019; 66:e12537. [PMID: 30403303 DOI: 10.1111/jpi.12537] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/11/2018] [Accepted: 10/26/2018] [Indexed: 12/13/2022]
Abstract
Melatonin-deficient rice with a semidwarf erect-leaf phenotype was created by suppressing serotonin N-acetyltransferase 2 (SNAT2). We generated an RNAi transgenic rice that suppressed tryptophan decarboxylase (TDC), which encodes the first TDC enzyme committed step for melatonin biosynthesis in plants catalyzing the conversion of tryptophan into tryptamine, to determine whether other transgenic rice with downregulated melatonin biosynthetic genes exhibited the same erect-leaf phenotype as the snat2 RNAi rice. The TDC RNAi rice produced significantly less melatonin than the wild type and exhibited a semidwarf phenotype, but no erect-leaf phenotype was observed. In contrast, tryptamine 5-hydroxylase (T5H) knockout Sekiguchi rice and caffeic acid O-methyltransferase (COMT) RNAi rice seedlings were semidwarf phenotypes with erect leaves, as was the snat2 RNAi rice due to a melatonin deficiency. All RNAi rice plants showing erect-leaf phenotypes had lower expression levels of the DWARF4 gene, which is a key enzyme for brassinosteroid (BR) biosynthesis, leading to lower BR levels than their respective wild types. Suppressing melatonin synthesis did not alter the contents of indole 3-acetic acid (IAA), suggesting the irrelevance of melatonin deficiency to IAA biosynthesis. These data indicate that a semidwarf seedling is a common rice phenotype by the lack of melatonin synthesis with or without BR suppression in a melatonin biosynthetic gene-specific manner.
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Affiliation(s)
- Kyungjin Lee
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea
| | - Kyoungwhan Back
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea
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21
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Melatonin: A Small Molecule but Important for Salt Stress Tolerance in Plants. Int J Mol Sci 2019; 20:ijms20030709. [PMID: 30736409 PMCID: PMC6387279 DOI: 10.3390/ijms20030709] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 02/03/2019] [Accepted: 02/04/2019] [Indexed: 01/09/2023] Open
Abstract
Salt stress is one of the most serious limiting factors in worldwide agricultural production, resulting in huge annual yield loss. Since 1995, melatonin (N-acetyl-5-methoxytryptamine)—an ancient multi-functional molecule in eukaryotes and prokaryotes—has been extensively validated as a regulator of plant growth and development, as well as various stress responses, especially its crucial role in plant salt tolerance. Salt stress and exogenous melatonin lead to an increase in endogenous melatonin levels, partly via the phyto-melatonin receptor CAND2/PMTR1. Melatonin plays important roles, as a free radical scavenger and antioxidant, in the improvement of antioxidant systems under salt stress. These functions improve photosynthesis, ion homeostasis, and activate a series of downstream signals, such as hormones, nitric oxide (NO) and polyamine metabolism. Melatonin also regulates gene expression responses to salt stress. In this study, we review recent literature and summarize the regulatory roles and signaling networks involving melatonin in response to salt stress in plants. We also discuss genes and gene families involved in the melatonin-mediated salt stress tolerance.
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Macedo Pereira G, Moreira LGL, Neto TDSN, Moreira de Almeida WA, Almeida-Lima J, Rocha HAO, Barbosa EG, Zuanazzi JAS, de Almeida MV, Grazul RM, Navarro-Vázquez A, Hallwass F, Ferreira LDS, Fernandes-Pedrosa MDF, Giordani RB. Isolation, spectral characterization, molecular docking, and cytotoxic activity of alkaloids from Erythroxylum pungens O. E. Shulz. PHYTOCHEMISTRY 2018; 155:12-18. [PMID: 30056276 DOI: 10.1016/j.phytochem.2018.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/13/2018] [Accepted: 07/14/2018] [Indexed: 06/08/2023]
Abstract
Stem bark, root bark, and leaf extracts of Erythroxylum pungens were subjected to phytochemical analysis. N,N-dimethyltryptamine (DMT) was isolated and characterized from E. pungens roots. This unprecedented result is remarkable since no indole alkaloid has been previously reported from Erythroxylaceae so far. Eleven known tropane alkaloids were identified by their mass spectra and 3-(2-methylbutyryloxy)tropan-6,7-diol as well as 3-(2-methylbutyryloxy)nortropan-6,7-diol were isolated and characterized based on mass spectrometry, 1H, 13C, COSY, and NOESY NMR analysis. The complete NMR data are reported for the first time. Inverse Structure-based and Ligand-Based virtual screening were carried out to identify possible targets for 3-(2-methylbutyryloxy)tropan-6,7-diol. The level of cytotoxicity of this tropane alkaloid aliphatic ester was discrete with potencies on the order of 0.3-1.0 mg/mL and better results against HeLa (50% cell viability reduction). Otherwise, atropine (0.3 mg/mL), a Solanaceae tropane alkaloid, and DMT (0.5 mg/mL) from E. pungens roots impaired at 50% the cell viability against HeLa, SiHa, PC3, and 786-0. This study stimulates scientific investigation of the impact of edaphoclimatic features in a semi-arid environment on tropane alkaloid biosynthesis.
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Affiliation(s)
| | | | | | | | - Jailma Almeida-Lima
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | | | | | - José Angelo S Zuanazzi
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | | | - Armando Navarro-Vázquez
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | - Fernando Hallwass
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | | | | | - Raquel Brandt Giordani
- Departamento de Farmácia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
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23
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Jiki Z, Lecour S, Nduhirabandi F. Cardiovascular Benefits of Dietary Melatonin: A Myth or a Reality? Front Physiol 2018; 9:528. [PMID: 29867569 PMCID: PMC5967231 DOI: 10.3389/fphys.2018.00528] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/24/2018] [Indexed: 12/14/2022] Open
Abstract
The role of the diet as well as the impact of the dietary habits on human health and disease is well established. Apart from its sleep regulatory effect, the indoleamine melatonin is a well-established antioxidant molecule with multiple health benefits. Convincing evidence supports the presence of melatonin in plants and foods with the intake of such foods affecting circulating melatonin levels in humans. While numerous actions of both endogenous melatonin and melatonin supplementation are well described, little is known about the influence of the dietary melatonin intake on human health. In the present review, evidence for the cardiovascular health benefits of melatonin supplementation and dietary melatonin is discussed. Current knowledge on the biological significance as well as the underlying physiological mechanism of action of the dietary melatonin is also summarized. Whether dietary melatonin constitutes an alternative preventive treatment for cardiovascular disease is addressed.
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Affiliation(s)
- Zukiswa Jiki
- Cardioprotection Group, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Sandrine Lecour
- Cardioprotection Group, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Frederic Nduhirabandi
- Cardioprotection Group, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Lee K, Back K. Overexpression of rice serotonin N-acetyltransferase 1 in transgenic rice plants confers resistance to cadmium and senescence and increases grain yield. J Pineal Res 2017; 62. [PMID: 28118490 DOI: 10.1111/jpi.12392] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/20/2017] [Indexed: 12/14/2022]
Abstract
While ectopic overexpression of serotonin N-acetyltransferase (SNAT) in plants has been accomplished using animal SNAT genes, ectopic overexpression of plant SNAT genes in plants has not been investigated. Because the plant SNAT protein differs from that of animals in its subcellular localization and enzyme kinetics, its ectopic overexpression in plants would be expected to give outcomes distinct from those observed from overexpression of animal SNAT genes in transgenic plants. Consistent with our expectations, we found that transgenic rice plants overexpressing rice (Oryza sativa) SNAT1 (OsSNAT1) did not show enhanced seedling growth like that observed in ovine SNAT-overexpressing transgenic rice plants, although both types of plants exhibited increased melatonin levels. OsSNAT1-overexpressing rice plants did show significant resistance to cadmium and senescence stresses relative to wild-type controls. In contrast to tomato, melatonin synthesis in rice seedlings was not induced by selenium and OsSNAT1 transgenic rice plants did not show tolerance to selenium. T2 homozygous OsSNAT1 transgenic rice plants exhibited increased grain yield due to increased panicle number per plant under paddy field conditions. These benefits conferred by ectopic overexpression of OsSNAT1 had not been observed in transgenic rice plants overexpressing ovine SNAT, suggesting that plant SNAT functions differently from animal SNAT in plants.
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Affiliation(s)
- Kyungjin Lee
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea
| | - Kyoungwhan Back
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea
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Back K, Tan DX, Reiter RJ. Melatonin biosynthesis in plants: multiple pathways catalyze tryptophan to melatonin in the cytoplasm or chloroplasts. J Pineal Res 2016; 61:426-437. [PMID: 27600803 DOI: 10.1111/jpi.12364] [Citation(s) in RCA: 239] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 09/02/2016] [Indexed: 02/06/2023]
Abstract
Melatonin is an animal hormone as well as a signaling molecule in plants. It was first identified in plants in 1995, and almost all enzymes responsible for melatonin biosynthesis had already been characterized in these species. Melatonin biosynthesis from tryptophan requires four-step reactions. However, six genes, that is, TDC, TPH, T5H, SNAT, ASMT, and COMT, have been implicated in the synthesis of melatonin in plants, suggesting the presence of multiple pathways. Two major pathways have been proposed based on the enzyme kinetics: One is the tryptophan/tryptamine/serotonin/N-acetylserotonin/melatonin pathway, which may occur under normal growth conditions; the other is the tryptophan/tryptamine/serotonin/5-methoxytryptamine/melatonin pathway, which may occur when plants produce large amounts of serotonin, for example, upon senescence. The melatonin biosynthetic capacity associated with conversion of tryptophan to serotonin is much higher than that associated with conversion of serotonin to melatonin, which yields a low level of melatonin synthesis in plants. Many melatonin intermediates are produced in various subcellular compartments, such as the cytoplasm, endoplasmic reticulum, and chloroplasts, which either facilitates or impedes the subsequent enzymatic steps. Depending on the pathways, the final subcellular sites of melatonin synthesis vary at either the cytoplasm or chloroplasts, which may differentially affect the mode of action of melatonin in plants.
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Affiliation(s)
- Kyoungwhan Back
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea.
| | - Dun-Xian Tan
- Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Russel J Reiter
- Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
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Byeon Y, Lee HY, Back K. Cloning and characterization of the serotonin N-acetyltransferase-2 gene (SNAT2) in rice (Oryza sativa). J Pineal Res 2016; 61:198-207. [PMID: 27121038 DOI: 10.1111/jpi.12339] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 04/26/2016] [Indexed: 01/02/2023]
Abstract
The penultimate enzyme in melatonin synthesis is serotonin N-acetyltransferase (SNAT), which exists as a single copy in mammals and plants. Our recent studies of the Arabidopsis snat-knockout mutant and SNAT RNAi rice (Oryza sativa) plants predicted the presence of at least one other SNAT isogene in plants; that is, the snat-knockout mutant of Arabidopsis and the SNAT RNAi rice plants still produced melatonin, even in the absence or the suppression of SNAT expression. Here, we report a molecular cloning of an SNAT isogene (OsSNAT2) from rice. The mature amino acid sequences of SNAT proteins indicated that OsSNAT2 and OsSNAT1 proteins had 39% identity values and 60% similarity. The Km and Vmax values of the purified recombinant OsSNAT2 were 371 μm and 4700 pmol/min/mg protein, respectively; the enzyme's optimal activity temperature was 45°C. Confocal microscopy showed that the OsSNAT2 protein was localized to both the cytoplasm and chloroplasts. The in vitro enzyme activity of OsSNAT2 was severely inhibited by melatonin, but the activities of sheep SNAT (OaSNAT) and rice OsSNAT1 proteins were not. The enzyme activity of OsSNAT2 was threefold higher than that of OsSNAT1, but 232-fold lower than that of OaSNAT. The OsSNAT1 and OsSNAT2 transcripts were similarly suppressed in rice leaves during the melatonin induction after cadmium treatment. Phylogenetic analyses indicated that OsSNAT1 and OsSNAT2 are distantly related, suggesting that they evolved independently from Cyanobacteria prior to the endosymbiosis event.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
| | - Hyoung Yool Lee
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
| | - Kyoungwhan Back
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
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27
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Hardeland R. Melatonin in Plants - Diversity of Levels and Multiplicity of Functions. FRONTIERS IN PLANT SCIENCE 2016; 7:198. [PMID: 26925091 PMCID: PMC4759497 DOI: 10.3389/fpls.2016.00198] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/04/2016] [Indexed: 05/18/2023]
Abstract
Melatonin has been detected in numerous plant species. A particularly surprising finding concerns the highly divergent levels of melatonin that vary between species, organs and environmental conditions, from a few pg/g to over 20 μg/g, reportedly up to 200 μg/g. Highest values have been determined in oily seeds and in plant organs exposed to high UV radiation. The divergency of melatonin concentrations is discussed under various functional aspects and focused on several open questions. This comprises differences in precursor availability, catabolism, the relative contribution of isoenzymes of the melatonin biosynthetic pathway, and differences in rate limitation by either serotonin N-acetyltransferase or N-acetylserotonin O-methyltransferase. Other differences are related to the remarkable pleiotropy of melatonin, which exhibits properties as a growth regulator and morphogenetic factor, actually debated in terms of auxin-like effects, and as a signaling molecule that modulates pathways of ethylene, abscisic, jasmonic and salicylic acids and is involved in stress tolerance, pathogen defense and delay of senescence. In the context of high light/UV intensities, elevated melatonin levels exceed those required for signaling via stress-related phytohormones and may comprise direct antioxidant and photoprotectant properties, perhaps with a contribution of its oxidatively formed metabolites, such as N (1)-acetyl-N (2)-formyl-5-methoxykynuramine and its secondary products. High melatonin levels in seeds may also serve antioxidative protection and have been shown to promote seed viability and germination capacity.
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Tan DX, Manchester LC, Esteban-Zubero E, Zhou Z, Reiter RJ. Melatonin as a Potent and Inducible Endogenous Antioxidant: Synthesis and Metabolism. Molecules 2015; 20:18886-906. [PMID: 26501252 PMCID: PMC6332205 DOI: 10.3390/molecules201018886] [Citation(s) in RCA: 381] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/08/2015] [Accepted: 10/09/2015] [Indexed: 11/17/2022] Open
Abstract
Melatonin is a tryptophan-derived molecule with pleiotropic activities. It is present in almost all or all organisms. Its synthetic pathway depends on the species in which it is measured. For example, the tryptophan to melatonin pathway differs in plants and animals. It is speculated that the melatonin synthetic machinery in eukaryotes was inherited from bacteria as a result of endosymbiosis. However, melatonin's synthetic mechanisms in microorganisms are currently unknown. Melatonin metabolism is highly complex with these enzymatic processes having evolved from cytochrome C. In addition to its enzymatic degradation, melatonin is metabolized via pseudoenzymatic and free radical interactive processes. The metabolic products of these processes overlap and it is often difficult to determine which process is dominant. However, under oxidative stress, the free radical interactive pathway may be featured over the others. Because of the complexity of the melatonin degradative processes, it is expected that additional novel melatonin metabolites will be identified in future investigations. The original and primary function of melatonin in early life forms such as in unicellular organisms was as a free radical scavenger and antioxidant. During evolution, melatonin was selected as a signaling molecule to transduce the environmental photoperiodic information into an endocrine message in multicellular organisms and for other purposes as well. As an antioxidant, melatonin exhibits several unique features which differ from the classic antioxidants. These include its cascade reaction with free radicals and its capacity to be induced under moderate oxidative stress. These features make melatonin a potent endogenously-occurring antioxidant that protects organisms from catastrophic oxidative stress.
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Affiliation(s)
- Dun-Xian Tan
- Department of Cellular and Structural Biology, Health Science Center, University of Texas, San Antonio, TX 78229, USA.
| | - Lucien C Manchester
- Department of Cellular and Structural Biology, Health Science Center, University of Texas, San Antonio, TX 78229, USA.
| | - Eduardo Esteban-Zubero
- Department of Cellular and Structural Biology, Health Science Center, University of Texas, San Antonio, TX 78229, USA.
| | - Zhou Zhou
- Department of Cellular and Structural Biology, Health Science Center, University of Texas, San Antonio, TX 78229, USA.
| | - Russel J Reiter
- Department of Cellular and Structural Biology, Health Science Center, University of Texas, San Antonio, TX 78229, USA.
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Arnao MB, Hernández-Ruiz J. Functions of melatonin in plants: a review. J Pineal Res 2015; 59:133-50. [PMID: 26094813 DOI: 10.1111/jpi.12253] [Citation(s) in RCA: 409] [Impact Index Per Article: 45.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/05/2015] [Indexed: 02/06/2023]
Abstract
The number of studies on melatonin in plants has increased significantly in recent years. This molecule, with a large set of functions in animals, has also shown great potential in plant physiology. This review outlines the main functions of melatonin in the physiology of higher plants. Its role as antistress agent against abiotic stressors, such as drought, salinity, low and high ambient temperatures, UV radiation and toxic chemicals, is analyzed. The latest data on their role in plant-pathogen interactions are also discussed. Both abiotic and biotic stresses produce a significant increase in endogenous melatonin levels, indicating its possible role as effector in these situations. The existence of endogenous circadian rhythms in melatonin levels has been demonstrated in some species, and the data, although limited, suggest a central role of this molecule in the day/night cycles in plants. Finally, another aspect that has led to a large volume of research is the involvement of melatonin in aspects of plant development regulation. Although its role as a plant hormone is still far of from being fully established, its involvement in processes such as growth, rhizogenesis, and photosynthesis seems evident. The multiple changes in gene expression caused by melatonin point to its role as a multiregulatory molecule capable of coordinating many aspects of plant development. This last aspect, together with its role as an alleviating-stressor agent, suggests that melatonin is an excellent prospect for crop improvement.
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Affiliation(s)
- Marino B Arnao
- Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, Murcia, Spain
| | - Josefa Hernández-Ruiz
- Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, Murcia, Spain
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Byeon Y, Lee HY, Back K. Chloroplastic and cytoplasmic overexpression of sheep serotonin N-acetyltransferase in transgenic rice plants is associated with low melatonin production despite high enzyme activity. J Pineal Res 2015; 58:461-9. [PMID: 25782973 DOI: 10.1111/jpi.12231] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/13/2015] [Indexed: 01/05/2023]
Abstract
Serotonin N-acetyltransferase (SNAT), the penultimate enzyme in melatonin biosynthesis, catalyzes the conversion of serotonin into N-acetylserotonin. Plant SNAT is localized in chloroplasts. To test SNAT localization effects on melatonin synthesis, we generated transgenic rice plants overexpressing a sheep (Ovis aries) SNAT (OaSNAT) in their chloroplasts and compared melatonin biosynthesis with that of transgenic rice plants overexpressing OaSNAT in their cytoplasm. To localize the OaSNAT in chloroplasts, we used a chloroplast targeting sequence (CTS) from tobacco protoporphyrinogen IX oxidase (PPO), which expresses in chloroplasts. The purified recombinant CTS:OaSNAT fusion protein was enzymatically functional and localized in chloroplasts as confirmed by confocal microscopic analysis. The chloroplast-targeted CTS:OaSNAT lines and cytoplasm-expressed OaSNAT lines had similarly high SNAT enzyme activities. However, after cadmium and butafenacil treatments, melatonin production in rice leaves was severalfold lower in the CTS:OaSNAT lines than in the OaSNAT lines. Notably, enhanced SNAT enzyme activity was not directly proportional to the production of N-acetylserotonin, melatonin, or 2-hydroxymelatonin, suggesting that plant SNAT has a role in the homeostatic regulation of melatonin rather than in accelerating melatonin synthesis.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Bioenergy Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, South Korea
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31
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Byeon Y, Lee HY, Hwang OJ, Lee HJ, Lee K, Back K. Coordinated regulation of melatonin synthesis and degradation genes in rice leaves in response to cadmium treatment. J Pineal Res 2015; 58:470-8. [PMID: 25783167 DOI: 10.1111/jpi.12232] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 03/13/2015] [Indexed: 12/14/2022]
Abstract
We investigated the expression patterns of genes involved in melatonin synthesis and degradation in rice leaves upon cadmium (Cd) treatment and the subcellular localization sites of melatonin 2-hydroxylase (M2H) proteins. The Cd-induced synthesis of melatonin coincided with the increased expression of melatonin biosynthetic genes including tryptophan decarboxylase (TDC), tryptamine 5-hydroxylase (T5H), and N-acetylserotonin methyltransferase (ASMT). However, the expression of serotonin N-acetyltransferase (SNAT), the penultimate gene in melatonin biosynthesis, was downregulated, suggesting that melatonin synthesis was counter-regulated by SNAT. Notably, the induction of melatonin biosynthetic gene expression was coupled with the induction of four M2H genes involved in melatonin degradation, which suggests that genes for melatonin synthesis and degradation are coordinately regulated. The induced M2H gene expression was correlated with enhanced M2H enzyme activity. Three of the M2H proteins were localized to the cytoplasm and one M2H protein was localized to chloroplasts, indicating that melatonin degradation occurs both in the cytoplasm and in chloroplasts. The biological activity of 2-hydroxymelatonin in the induction of the plant defense gene expression was 50% less than that of melatonin, which indicates that 2-hydroxymelatonin may be a metabolite of melatonin. Overall, our data demonstrate that melatonin synthesis occurs in parallel with melatonin degradation in both chloroplasts and cytoplasm, and the resulting melatonin metabolite 2-hydroxymelatonin also acts as a signaling molecule for defense gene induction.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Bioenergy Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, South Korea
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Phytomelatonin: assisting plants to survive and thrive. Molecules 2015; 20:7396-437. [PMID: 25911967 PMCID: PMC6272735 DOI: 10.3390/molecules20047396] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 03/27/2015] [Accepted: 03/27/2015] [Indexed: 12/15/2022] Open
Abstract
This review summarizes the advances that have been made in terms of the identified functions of melatonin in plants. Melatonin is an endogenously-produced molecule in all plant species that have been investigated. Its concentration in plant organs varies in different tissues, e.g., roots versus leaves, and with their developmental stage. As in animals, the pathway of melatonin synthesis in plants utilizes tryptophan as an essential precursor molecule. Melatonin synthesis is inducible in plants when they are exposed to abiotic stresses (extremes of temperature, toxins, increased soil salinity, drought, etc.) as well as to biotic stresses (fungal infection). Melatonin aids plants in terms of root growth, leaf morphology, chlorophyll preservation and fruit development. There is also evidence that exogenously-applied melatonin improves seed germination, plant growth and crop yield and its application to plant products post-harvest shows that melatonin advances fruit ripening and may improve food quality. Since melatonin was only discovered in plants two decades ago, there is still a great deal to learn about the functional significance of melatonin in plants. It is the hope of the authors that the current review will serve as a stimulus for scientists to join the endeavor of clarifying the function of this phylogenetically-ancient molecule in plants and particularly in reference to the mechanisms by which melatonin mediates its multiple actions.
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Byeon Y, Back K. Molecular cloning of melatonin 2-hydroxylase responsible for 2-hydroxymelatonin production in rice (Oryza sativa). J Pineal Res 2015; 58:343-51. [PMID: 25728912 DOI: 10.1111/jpi.12220] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/20/2015] [Indexed: 12/26/2022]
Abstract
Although melatonin biosynthetic genes from plants have been cloned, the melatonin catabolism mechanisms remain unclear. To clone the genes responsible for melatonin metabolism, we ectopically expressed 35 full-length cDNAs of rice 2-oxoglutarate-dependent dioxygenase (2-ODD) in Escherichia coli and purified the corresponding recombinant proteins. In vitro 2-ODD assays showed four independent 2-ODD proteins that were able to catalyze melatonin into 2-hydroxymelatonin, exhibiting melatonin 2-hydroxylase (M2H). These M2H proteins had peak activities at pH 8.0 and 30°C. The Km ranged from 121 μm to 371 μm with the Vmax ranging from 1.7 to 18.5 pkat/mg protein, respectively. The M2H enzyme activities were dependent on cofactors such as α-ketoglutarate, ascorbate, and Fe(2+), similar to the 2-ODD enzymes. M2H activity was inhibited by prohexadione-Ca, an inhibitor of 2-ODD, in a dose-dependent manner. M2H activity was high in the roots of rice seedlings, concurrent with high transcription levels of 2-ODD 21, suggesting that 2-ODD 21 was a major gene for M2H activity. Analogous to the high M2H activity in the roots, 2-hydroxymelatonin was found in large quantities in roots treated with melatonin. These results suggest that melatonin was metabolized into 2-hydroxymelatonin by the M2H genes in plants, but the physiological significance of 2-hydroxymelatonin remains to be examined in the future.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea
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34
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Byeon Y, Yool Lee H, Choi DW, Back K. Chloroplast-encoded serotonin N-acetyltransferase in the red alga Pyropia yezoensis: gene transition to the nucleus from chloroplasts. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:709-17. [PMID: 25183745 PMCID: PMC4321536 DOI: 10.1093/jxb/eru357] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Melatonin biosynthesis involves the N-acetylation of arylalkylamines such as serotonin, which is catalysed by serotonin N-acetyltransferase (SNAT), the penultimate enzyme of melatonin biosynthesis in both animals and plants. Here, we report the functional characterization of a putative N-acetyltransferase gene in the chloroplast genome of the alga laver (Pyropia yezoensis, formerly known as Porphyra yezoensis) with homology to the rice SNAT gene. To confirm that the putative Pyropia yezoensis SNAT (PySNAT) gene encodes an SNAT, we cloned the full-length chloroplastidic PySNAT gene by PCR and purified the recombinant PySNAT protein from Escherichia coli. PySNAT was 174 aa and had 50% amino acid identity with cyanobacteria SNAT. Purified recombinant PySNAT showed a peak activity at 55 °C with a K m of 467 µM and V max of 28 nmol min-1 mg(-1) of protein. Unlike other plant SNATs, PySNAT localized to the cytoplasm due to a lack of N-terminal chloroplast transit peptides. Melatonin was present at 0.16ng g(-1) of fresh mass but increased during heat stress. Phylogenetic analysis of the sequence suggested that PySNAT has evolved from the cyanobacteria SNAT gene via endosymbiotic gene transfer. Additionally, the chloroplast transit peptides of plant SNATs were acquired 1500 million years ago, concurrent with the appearance of green algae.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Interdisciplinary Program of Bioenergy and Biomaterials, Bioenergy Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Republic of Korea
| | - Hyoung Yool Lee
- Department of Biotechnology, Interdisciplinary Program of Bioenergy and Biomaterials, Bioenergy Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Republic of Korea
| | - Dong-Woog Choi
- Department of Biology Education, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Kyoungwhan Back
- Department of Biotechnology, Interdisciplinary Program of Bioenergy and Biomaterials, Bioenergy Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Republic of Korea
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35
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Hardeland R. Melatonin in plants and other phototrophs: advances and gaps concerning the diversity of functions. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:627-46. [PMID: 25240067 DOI: 10.1093/jxb/eru386] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Melatonin is synthesized in Alphaproteobacteria, Cyanobacteria, Dinoflagellata, Euglenoidea, Rhodophyta, Phae ophyta, and Viridiplantae. The biosynthetic pathways have been identified in dinoflagellates and plants. Other than in dinoflagellates and animals, tryptophan is not 5-hydroxylated in plants but is first decarboxylated. Serotonin is formed by 5-hydroxylation of tryptamine. Serotonin N-acetyltransferase is localized in plastids and lacks homology to the vertebrate aralkylamine N-acetyltransferase. Melatonin content varies considerably among species, from a few picograms to several micrograms per gram, a strong hint for different actions of this indoleamine. At elevated levels, the common and presumably ancient property as an antioxidant may prevail. Although melatonin exhibits nocturnal maxima in some phototrophs, it is not generally a mediator of the signal 'darkness'. In various plants, its formation is upregulated by visible and/or UV light. Increases are often induced by high or low temperature and several other stressors including drought, salinity, and chemical toxins. In Arabidopsis, melatonin induces cold- and stress-responsive genes. It has been shown to support cold resistance and to delay experimental leaf senescence. Transcriptome data from Arabidopsis indicate upregulation of genes related to ethylene, abscisic acid, jasmonic acid, and salicylic acid. Auxin-like actions have been reported concerning root growth and inhibition, and hypocotyl or coleoptile lengthening, but effects caused by melatonin and auxins can be dissected. Assumptions on roles in flower morphogenesis and fruit ripening are based mainly on concentration changes. Whether or not melatonin will find a place in the phytohormone network depends especially on the identification of molecular signals regulating its synthesis, high-affinity binding sites, and signal transduction pathways.
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Affiliation(s)
- Rüdiger Hardeland
- Johann Friedrich Blumenbach Institute of Zoology and Anthropology, University of Göttingen, Berliner Strasse 28, D-37073 Göttingen, Germany
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Erland LAE, Murch SJ, Reiter RJ, Saxena PK. A new balancing act: The many roles of melatonin and serotonin in plant growth and development. PLANT SIGNALING & BEHAVIOR 2015; 10:e1096469. [PMID: 26418957 PMCID: PMC4883872 DOI: 10.1080/15592324.2015.1096469] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/11/2015] [Accepted: 09/14/2015] [Indexed: 05/20/2023]
Abstract
Melatonin and serotonin are indoleamines first identified as neurotransmitters in vertebrates; they have now been found to be ubiquitously present across all forms of life. Both melatonin and serotonin were discovered in plants several years after their discovery in mammals, but their presence has now been confirmed in almost all plant families. The mechanisms of action of melatonin and serotonin are still poorly defined. Melatonin and serotonin possess important roles in plant growth and development, including functions in chronoregulation and modulation of reproductive development, control of root and shoot organogenesis, maintenance of plant tissues, delay of senescence, and responses to biotic and abiotic stresses. This review focuses on the roles of melatonin and serotonin as a novel class of plant growth regulators. Their roles in reproductive and vegetative plant growth will be examined including an overview of current hypotheses and knowledge regarding their mechanisms of action in specific responses.
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Affiliation(s)
- Lauren A E Erland
- Department of Plant Agriculture; University of Guelph; Guelph, Canada
| | - Susan J Murch
- Department of Chemistry; University of British Columbia; Kelowna, Canada
| | - Russel J Reiter
- Department of Cellular and Structural Biology; University of Texas Health Center; San Antonio, TX USA
| | - Praveen K Saxena
- Department of Plant Agriculture; University of Guelph; Guelph, Canada
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Arnao MB, Hernández-Ruiz J. Melatonin: plant growth regulator and/or biostimulator during stress? TRENDS IN PLANT SCIENCE 2014; 19:789-97. [PMID: 25156541 DOI: 10.1016/j.tplants.2014.07.006] [Citation(s) in RCA: 314] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/14/2014] [Accepted: 07/24/2014] [Indexed: 05/18/2023]
Abstract
Melatonin regulates the growth of roots, shoots, and explants, to activate seed germination and rhizogenesis and to delay induced leaf senescence. The antioxidant properties of melatonin would seem to explain, at least partially, its ability to fortify plants subjected to abiotic stress. In this Review we examine recent data on the gene-regulation capacity of melatonin that point to many interesting features, such as the upregulation of anti-stress genes and recent aspects of the auxin-independent effects of melatonin as a plant growth regulator. This, together with the recent data on endogenous melatonin biosynthesis induction by environmental factors, makes melatonin an interesting candidate for use as a natural biostimulating treatment for field crops.
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Affiliation(s)
- Marino B Arnao
- Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, 30100 Murcia, Spain.
| | - Josefa Hernández-Ruiz
- Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, 30100 Murcia, Spain
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38
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Byeon Y, Lee HY, Lee K, Back K. A rice chloroplast transit peptide sequence does not alter the cytoplasmic localization of sheep serotonin N-acetyltransferase expressed in transgenic rice plants. J Pineal Res 2014; 57:147-54. [PMID: 24920304 DOI: 10.1111/jpi.12151] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/06/2014] [Indexed: 12/20/2022]
Abstract
Ectopic overexpression of melatonin biosynthetic genes of animal origin has been used to generate melatonin-rich transgenic plants to examine the functional roles of melatonin in plants. However, the subcellular localization of these proteins expressed in the transgenic plants remains unknown. We studied the localization of sheep (Ovis aries) serotonin N-acetyltransferase (OaSNAT) and a translational fusion of a rice SNAT transit peptide to OaSNAT (TS:OaSNAT) in plants. Laser confocal microscopy analysis revealed that both OaSNAT and TS:OaSNAT proteins were localized to the cytoplasm even with the addition of the transit sequence to OaSNAT. Transgenic rice plants overexpressing the TS:OaSNAT fusion transgene exhibited high SNAT enzyme activity relative to untransformed wild-type plants, but lower activity than transgenic rice plants expressing the wild-type OaSNAT gene. Melatonin levels in both types of transgenic rice plant corresponded well with SNAT enzyme activity levels. The TS:OaSNAT transgenic lines exhibited increased seminal root growth relative to wild-type plants, but less than in the OaSNAT transgenic lines, confirming that melatonin promotes root growth. Seed-specific OaSNAT expression under the control of a rice prolamin promoter did not confer high levels of melatonin production in transgenic rice seeds compared with seeds from transgenic plants expressing OaSNAT under the control of the constitutive maize ubiquitin promoter.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
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Feng X, Wang M, Zhao Y, Han P, Dai Y. Melatonin from different fruit sources, functional roles, and analytical methods. Trends Food Sci Technol 2014. [DOI: 10.1016/j.tifs.2014.02.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Byeon Y, Park S, Lee HY, Kim YS, Back K. Elevated production of melatonin in transgenic rice seeds expressing rice tryptophan decarboxylase. J Pineal Res 2014; 56:275-82. [PMID: 24433490 DOI: 10.1111/jpi.12120] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/10/2014] [Indexed: 12/15/2022]
Abstract
A major goal of plant biotechnology is to improve the nutritional qualities of crop plants through metabolic engineering. Melatonin is a well-known bioactive molecule with an array of health-promoting properties, including potent antioxidant capability. To generate melatonin-rich rice plants, we first independently overexpressed three tryptophan decarboxylase isogenes in the rice genome. Melatonin levels were altered in the transgenic lines through overexpression of TDC1, TDC2, and TDC3; TDC3 transgenic seed (TDC3-1) had melatonin concentrations 31-fold higher than those of wild-type seeds. In TDC3 transgenic seedlings, however, only a doubling of melatonin content occurred over wild-type levels. Thus, a seed-specific accumulation of melatonin appears to occur in TDC3 transgenic lines. In addition to increased melatonin content, TDC3 transgenic lines also had enhanced levels of melatonin intermediates including 5-hydroxytryptophan, tryptamine, serotonin, and N-acetylserotonin. In contrast, expression levels of melatonin biosynthetic mRNA did not increase in TDC3 transgenic lines, indicating that increases in melatonin and its intermediates in these lines are attributable exclusively to overexpression of the TDC3 gene.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Interdisciplinary Program of Bioenergy and Biomaterials, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
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Byeon Y, Back K. Melatonin synthesis in rice seedlings in vivo is enhanced at high temperatures and under dark conditions due to increased serotonin N-acetyltransferase and N-acetylserotonin methyltransferase activities. J Pineal Res 2014; 56:189-95. [PMID: 24313332 DOI: 10.1111/jpi.12111] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/03/2013] [Indexed: 12/20/2022]
Abstract
Temperature and light are important environmental factors for plant growth and development. The final two enzymes in the melatonin synthesis pathway in plants are serotonin N-acetyltransferase (SNAT) and N-acetylserotonin methyltransferase (ASMT), which have thermophilic characteristics. Thus, the effects of temperature and light on melatonin synthesis in rice seedlings were investigated. Here, we demonstrated that melatonin levels increased as temperature increased when rice seedlings were exposed to various temperatures for 1 hr. Moreover, the relative melatonin levels were higher in the dark. For example, exposure of rice seedlings to 1-hr darkness at 55°C resulted in a melatonin yield of 4.9 ng/g fresh weight (fw), compared with 2.95 ng/g fw under light conditions. Temperature-dependent melatonin synthesis was closely associated with an increase in both SNAT and ASMT activities, but not with transcript levels of melatonin biosynthetic genes. The daily melatonin levels in field-grown rice plants were unaffected as the positive effect of the relatively high temperature during the day was counteracted by the negative effect of the high light. The opposite effect occurred during the night, in which the positive effect of darkness on melatonin synthesis was counteracted by the negative effect of a low temperature.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Interdisciplinary Program of Bioenergy and Biomaterials, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea
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Byeon Y, Lee HY, Lee K, Park S, Back K. Cellular localization and kinetics of the rice melatonin biosynthetic enzymes SNAT and ASMT. J Pineal Res 2014; 56:107-14. [PMID: 24134674 DOI: 10.1111/jpi.12103] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/15/2013] [Indexed: 12/13/2022]
Abstract
Serotonin N-acetyltransferase (SNAT) and N-acetylserotonin methyltransferase (ASMT) are the final two enzymes in the melatonin synthesis pathway in plants. Although their corresponding genes have been cloned, their cellular localization and enzymatic characteristics are unknown. Using confocal microscopy, we showed that SNAT protein is localized in chloroplasts, whereas ASMT is expressed in the cytoplasm. In vitro measurement of ASMT enzyme activity revealed a peak of activity in roots, but SNAT enzyme activity was not detected in any plant tissues. This may be attributed in part to an effect of chlorophyll because SNAT enzyme activity was greatly inhibited by chlorophyll in a dose-dependent manner. Because the SNAT protein of cyanobacteria is thermophilic, we examined the effect of temperature on the activity of the rice SNAT and ASMT enzymes. Purified recombinant rice SNAT and ASMT enzymes had an optimum temperature for activity of 55°C. The Km and Vmax values for SNAT at 55°C were 270 μm and 3.3 nmol/min/mg protein, whereas the Km and Vmax for ASMT were 222 μm and 9 nmol/min/mg protein, respectively. The catalytic efficiency (Vmax /Km ) values of SNAT and ASMT were 16-fold and 4054-fold higher at 55°C than at 30°C suggestive of increased melatonin production at high temperature in plants.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Interdisciplinary Program of Bioenergy and Biomaterials, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
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Wang P, Sun X, Chang C, Feng F, Liang D, Cheng L, Ma F. Delay in leaf senescence of Malus hupehensis by long-term melatonin application is associated with its regulation of metabolic status and protein degradation. J Pineal Res 2013; 55:424-34. [PMID: 24103092 DOI: 10.1111/jpi.12091] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 08/23/2013] [Indexed: 01/07/2023]
Abstract
Melatonin has an important anti-aging role in plant physiology. We tested the effects of long-term melatonin exposure on metabolic status and protein degradation during natural leaf senescence in trees of Malus hupehensis Rehd. The 2-month regular supplement of 100 μm melatonin to the soil once every 6 days altered the metabolic status and delayed protein degradation. For example, leaves from treated plants had significantly higher photosynthetic activity, chlorophyll concentrations, and levels of three photosynthetic end products (sorbitol, sucrose, and starch) when compared with the control. The significant inhibition of hexose (fructose and glucose) accumulation possibly regulated the signaling of MdHXK1, a gene for which expression was also repressed by melatonin during senescence. The plants also exhibited better preservation of their nitrogen, total soluble protein, and Rubisco protein concentrations than the control. The slower process of protein degradation might be a result of melatonin-linked inhibition on the expression of apple autophagy-related genes (ATGs). Our results are the first to provide evidence for this delay in senescence based on the metabolic alteration and protein degradation.
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Affiliation(s)
- Ping Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China
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Byeon Y, Lee K, Park YI, Park S, Back K. Molecular cloning and functional analysis of serotonin N-acetyltransferase from the cyanobacterium Synechocystis sp. PCC 6803. J Pineal Res 2013; 55:371-6. [PMID: 23952748 DOI: 10.1111/jpi.12080] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/19/2013] [Indexed: 01/13/2023]
Abstract
Serotonin N-acetyltransferase (SNAT) catalyzes conversion of serotonin into N-acetylserotonin, which is a direct precursor for melatonin biosynthesis in all organisms. Molecular cloning of plant SNAT from rice led to a screening for SNAT homolog genes in other species. We identified a cyanobacterium SNAT-like gene (cSNAT) that showed 56% amino acid homology with the rice SNAT. To confirm whether cSNAT encoded SNAT enzyme activity, we expressed cSNAT DNA in Escherichia coli and purified the cSNAT protein as a C-terminal His-tagged form. The purified cSNAT protein exhibited SNAT enzyme activities, transferring the acetyl group into either serotonin or tryptamine substrates. The optimum temperature was 55°C, but it was still highly active at 70°C, suggesting that cSNAT is a thermotolerant enzyme. The Km and Vmax were 823 μm and 1.6 nmol/min/mg protein, respectively. The cSNAT gene is highly conserved in all cyanobacterial taxa and seems to be an origin of SNAT in higher plants. The thermotolerance of cSNAT suggests that melatonin plays a role in the response to high-temperature stress. Further analysis of this role of melatonin in higher plants is needed.
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Affiliation(s)
- Yeong Byeon
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
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Gardiner J. Evolutionary basins of attraction and convergence in plants and animals. Commun Integr Biol 2013; 6:e26760. [PMID: 24505506 PMCID: PMC3914912 DOI: 10.4161/cib.26760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/09/2013] [Indexed: 11/19/2022] Open
Abstract
Living organisms evolve, in part, according to the underlying properties of the amino acids and other compounds of which they are composed. Thus there are evolutionary basins of attraction that living organisms will tend to evolve toward. These processes are complex and probably beyond our current capabilities to fully envisage. But progress is being made toward an understanding of such principles by efforts to catalog protein folds and protein–protein interactions. Even plants and animals show convergent evolution, possibly driven by underlying evolutionary basins of attraction. Physical and chemical parameters and the properties of proteins present in the last common ancestor of these 2 taxa, including a putative connexin ancestor, may have played key roles here. Thus evolution is perhaps not as random as is sometimes depicted, but will follow predefined pathways. Here I address convergent evolution in plants and animals beginning at the molecular level and progressing to the organismic one.
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Affiliation(s)
- John Gardiner
- The School of Biological Sciences; The University of Sydney; Camperdown, NSW Australia
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Park S, Byeon Y, Back K. Functional analyses of three ASMT gene family members in rice plants. J Pineal Res 2013; 55:409-15. [PMID: 24033370 DOI: 10.1111/jpi.12088] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/05/2013] [Indexed: 01/13/2023]
Abstract
N-acetylserotonin methyltransferase (ASMT) is the final enzyme in a biosynthetic pathway that produces melatonin. ASMT may play a rate-limiting role in the production of this bioactive molecule in plants. There are three ASMT genes (ASMT1-ASMT3) in the rice genome, but only ASMT1 has been functionally characterized. A major barrier to further progress in characterizing these genes has been a failure of functional expression within the Escherichia coli. Purified recombinant ASMT2 and ASMT3 are inactive in ASMT enzyme catalysis. To determine the biological functions of ASMT2 and ASMT3, we first overexpressed them in rice calli, which resulted in enhanced production of melatonin in the respective transgenic calli. To further corroborate the functions of ASMT2 and ASMT3 as ASMT genes, we generated stable transgenic rice plants. ASMT enzyme activity was increased in comparison with the wild type in T2 homozygous transgenic rice plants expressing three ASMT genes independently. When seedlings were treated with 1 mm N-acetylserotonin (NAS), leaf melatonin contents were higher in the three transgenic lines than in the wild type. There were no significant differences between the transgenic lines and the wild type without this treatment. ASMT1 and ASMT2 transcripts were highly expressed in stems and flowers, but ASMT3 was barely detectable in any of the plant organs. All three ASMT mRNAs were simultaneously induced in treatments with abscisic and methyl jasmonic acids.
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Affiliation(s)
- Sangkyu Park
- Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea
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