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Erland LA. Views and perspectives on the indoleamines serotonin and melatonin in plants: past, present and future. PLANT SIGNALING & BEHAVIOR 2024; 19:2366545. [PMID: 38899558 PMCID: PMC11195476 DOI: 10.1080/15592324.2024.2366545] [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: 03/21/2024] [Accepted: 06/05/2024] [Indexed: 06/21/2024]
Abstract
In the decades since their discovery in plants in the mid-to-late 1900s, melatonin (N-acetyl-5-methoxytryptamine) and serotonin (5-methoxytryptamine) have been established as their own class of phytohormone and have become popular targets for examination and study as stress ameliorating compounds. The indoleamines play roles across the plant life cycle from reproduction to morphogenesis and plant environmental perception. There is growing interest in harnessing the power of these plant neurotransmitters in applied and agricultural settings, particularly as we face increasingly volatile climates for food production; however, there is still a lot to learn about the mechanisms of indoleamine action in plants. A recent explosion of interest in these compounds has led to exponential growth in the field of melatonin research in particular. This concept paper aims to summarize the current status of indoleamine research and highlight some emerging trends.
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Khan M, Hussain A, Yun BW, Mun BG. Melatonin: The Multifaceted Molecule in Plant Growth and Defense. Int J Mol Sci 2024; 25:6799. [PMID: 38928504 PMCID: PMC11203645 DOI: 10.3390/ijms25126799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 06/28/2024] Open
Abstract
Melatonin (MEL), a hormone primarily known for its role in regulating sleep and circadian rhythms in animals, has emerged as a multifaceted molecule in plants. Recent research has shed light on its diverse functions in plant growth and defense mechanisms. This review explores the intricate roles of MEL in plant growth and defense responses. MEL is involved in plant growth owing to its influence on hormone regulation. MEL promotes root elongation and lateral root formation and enhances photosynthesis, thereby promoting overall plant growth and productivity. Additionally, MEL is implicated in regulating the circadian rhythm of plants, affecting key physiological processes that influence plant growth patterns. MEL also exhibits antioxidant properties and scavenges reactive oxygen species, thereby mitigating oxidative stress. Furthermore, it activates defense pathways against various biotic stressors. MEL also enhances the production of secondary metabolites that contribute to plant resistance against environmental changes. MEL's ability to modulate plant response to abiotic stresses has also been extensively studied. It regulates stomatal closure, conserves water, and enhances stress tolerance by activating stress-responsive genes and modulating signaling pathways. Moreover, MEL and nitric oxide cooperate in stress responses, antioxidant defense, and plant growth. Understanding the mechanisms underlying MEL's actions in plants will provide new insights into the development of innovative strategies for enhancing crop productivity, improving stress tolerance, and combating plant diseases. Further research in this area will deepen our knowledge of MEL's intricate functions and its potential applications in sustainable agriculture.
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Affiliation(s)
- Murtaza Khan
- Department of Horticulture and Life Science, Yeungnam University, Gyeongsan 38541, Republic of Korea
| | - Adil Hussain
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
- Department of Entomology, Abdul Wali Khan University Mardan, Mardan 23200, Pakistan
| | - Byung-Wook Yun
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Bong-Gyu Mun
- Department of Environmental and Biological Chemistry, Chungbuk National University, Cheongju 28644, Republic of Korea
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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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Mushtaq NU, Alghamdi KM, Saleem S, Tahir I, Bahieldin A, Henrissat B, Alghamdi MK, Rehman RU, Hakeem KR. Exogenous zinc mitigates salinity stress by stimulating proline metabolism in proso millet ( Panicum miliaceum L.). FRONTIERS IN PLANT SCIENCE 2023; 14:1053869. [PMID: 36968428 PMCID: PMC10036794 DOI: 10.3389/fpls.2023.1053869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
Salinity is one of the most concerning ecological restrictions influencing plant growth, which poses a devastating threat to global agriculture. Surplus quantities of ROS generated under stress conditions have negative effects on plants' growth and survival by damaging cellular components, including nucleic acids, lipids, proteins and carbohydrates. However, low levels of ROS are also necessary because of their role as signalling molecules in various development-related pathways. Plants possess sophisticated antioxidant systems for scavenging as well as regulating ROS levels to protect cells from damage. Proline is one such crucial non-enzymatic osmolyte of antioxidant machinery that functions in the reduction of stress. There has been extensive research on improving the tolerance, effectiveness, and protection of plants against stress, and to date, various substances have been used to mitigate the adverse effects of salt. In the present study Zinc (Zn) was applied to elucidate its effect on proline metabolism and stress-responsive mechanisms in proso millet. The results of our study indicate the negative impact on growth and development with increasing treatments of NaCl. However, the low doses of exogenous Zn proved beneficial in mitigating the effects of NaCl by improving morphological and biochemical features. In salt-treated plants, the low doses of Zn (1 mg/L, 2 mg/L) rescued the negative impact of salt (150mM) as evidenced by increase in shoot length (SL) by 7.26% and 25.5%, root length (RL) by 21.84% and 39.07% and membrane stability index (MSI) by 132.57% and 151.58% respectively.The proline content improved at all concentrations with maximum increase of 66.65% at 2 mg/L Zn. Similarly, the low doses of Zn also rescued the salt induced stress at 200mM NaCl. The enzymes related to proline biosynthesis were also improved at lower doses of Zn. In salt treated plants (150mM), Zn (1 mg/L, 2 mg/L) increased the activity of P5CS by 19.344% and 21%. The P5CR and OAT activities were also improved with maximum increase of 21.66% and 21.84% at 2 mg/L Zn respectively. Similarly, the low doses of Zn also increased the activities of P5CS, P5CR and OAT at 200mM NaCl. Whereas P5CDH enzyme activity showed a decrease of 82.5% at 2mg/L Zn+150mM NaCl and 56.7% at 2mg/L Zn+200 mM NaCl. These results strongly imply the modulatory role of Zn in maintaining of proline pool during NaCl stress.
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Affiliation(s)
- Naveed Ul Mushtaq
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Khalid M. Alghamdi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Seerat Saleem
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Inayatullah Tahir
- Department of Botany, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Ahmad Bahieldin
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Mohammed Khalid Alghamdi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Reiaz Ul Rehman
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Khalid Rehman Hakeem
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
- Princess Dr. Najla Bint Saud Al-Saud Center for Excellence Research in Biotechnology, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Public Health, Daffodil International University, Dhaka, Bangladesh
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Gupta A, Tiwari RK, Shukla R, Singh AN, Sahu PK. Salinity alleviator bacteria in rice ( Oryza sativa L.), their colonization efficacy, and synergism with melatonin. FRONTIERS IN PLANT SCIENCE 2023; 13:1060287. [PMID: 36714774 PMCID: PMC9878605 DOI: 10.3389/fpls.2022.1060287] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/12/2022] [Indexed: 06/18/2023]
Abstract
In this study, rhizospheric and endophytic bacteria were tested for the alleviation of salinity stress in rice. Endophytic isolates were taken from previous studies based on their salt stress-alleviating traits. The rhizospheric bacteria were isolated from rice and screened based on salt tolerance and plant growth-promoting traits. Molecular identification indicated the presence of class Gammaproteobacteria, Bacillota, and Actinomycetia. Two-two most potential isolates each from rhizospheric and endophytic bacteria were selected for in planta trials. Results showed that microbial inoculation significantly improved germination and seedling vigor under elevated salinity. The confocal scanning laser microscopy showed higher bacterial colonization in inoculated rice roots than in control. Based on this experiment, rhizospheric bacteria Brevibacterium frigoritolerans W19 and endophytic Bacillus safensis BTL5 were selected for pot trial along with a growth-inducing compound melatonin 20 ppm. Inoculation of these two bacteria improved the levels of chlorophyll, proline, phenylalanine ammonia-lyase, catalase, superoxide dismutase, polyphenol oxidase, root-shoot length, and dry weight under elevated salt concentration. The gene expression studies showed modulation of SOD1, CATa, NHX1, and PAL1 genes by the bacterial strains and melatonin application. The inoculation was found to have additive effects with 20 ppm melatonin. This enhancement in dry matter accumulation, compatible solute production, and oxidative stress regulation could help plants in mitigating the ill effects of high salinity. Exploring such a combination of microbes and inducer molecules could be potentially useful in developing stress-alleviating bioformulations.
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Affiliation(s)
- Amrita Gupta
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, India
- Indian Council of Agricultural Research (ICAR)-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Maunath Bhanjan, India
- Indian Council of Agricultural Research (ICAR)-Indian Institute of Seed Sciences, Kushmaur, Maunath Bhanjan, India
| | - Rajesh Kumar Tiwari
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, India
| | - Renu Shukla
- Indian Council of Agricultural Research (ICAR)-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Maunath Bhanjan, India
| | - Arvind Nath Singh
- Indian Council of Agricultural Research (ICAR)-Indian Institute of Seed Sciences, Kushmaur, Maunath Bhanjan, India
| | - Pramod Kumar Sahu
- Indian Council of Agricultural Research (ICAR)-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Maunath Bhanjan, India
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Li Y, Chu Y, Sun H, Bao Q, Huang Y. Melatonin alleviates arsenite toxicity by decreasing the arsenic accumulation in cell protoplasts and increasing the antioxidant capacity in rice. CHEMOSPHERE 2023; 312:137292. [PMID: 36403814 DOI: 10.1016/j.chemosphere.2022.137292] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/19/2022] [Accepted: 11/17/2022] [Indexed: 06/16/2023]
Abstract
Arsenic (As) is a common environmental pollutant that seriously interferes with the normal growth of organisms. There is an urgent need to take environment-safe and efficient strategies to mitigate As toxicity. Melatonin (MT) is a pleiotropic molecule that regulates plant growth and organ development and alleviates heavy metal stresses. The experiment aims to explore the mechanism of MT in reducing arsenite toxicity by hydroponic rice seedlings. The results showed that MT application reduced the As content in rice roots and shoots by 26.4% and 37.5%, respectively, and mainly decreased As content in the soluble fractions of the rice root cell. MT application also increased the As content of chelated-soluble pectin and alkali-soluble pectin in the cell wall by 14.7% and 74.4%, respectively. It promoted the generation of the functional group of the root cell walls by the FTIR analysis, indicating that MT may promote the fixation of As on the cell wall. Meanwhile, MT contributed to scavenging excess H2O2, reducing MDA content, and maintaining normal morphology of root cells by stimulating SOD, POD and CAT activities and increasing the level of GSH. The research deepens our understanding of how MT participates in maintaining redox homeostasis in rice cells, reducing As toxicity, and decreasing As concentration in rice seedlings, thereby providing more possibilities for reducing As accumulation in rice.
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Affiliation(s)
- Yan Li
- Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Yutan Chu
- Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Hongyu Sun
- Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Qiongli Bao
- Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
| | - Yizong Huang
- Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
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Kaya C, Ugurlar F, Ashraf M, Alyemeni MN, Bajguz A, Ahmad P. The involvement of hydrogen sulphide in melatonin-induced tolerance to arsenic toxicity in pepper (Capsicum annuum L.) plants by regulating sequestration and subcellular distribution of arsenic, and antioxidant defense system. CHEMOSPHERE 2022; 309:136678. [PMID: 36191761 DOI: 10.1016/j.chemosphere.2022.136678] [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: 08/23/2022] [Revised: 09/18/2022] [Accepted: 09/28/2022] [Indexed: 06/16/2023]
Abstract
Melatonin (MT) and hydrogen sulphide (H2S) are recognised as vital biomolecules actively taking part in plant defence systems as free radical scavengers and antioxidants against a myriad of biotic and abiotic stressors. However, it has been yet unknown in plants subjected to arsenic (As) toxicity whether or not H2S interacts with MT to regulate endogenous antioxidant defence system. Prior to beginning As stress (As-S) treatments, MT (0.10 mM) was applied externally to plants daily for three days. AsS was then started for two weeks with As(V) (0.1 mM as Na2HAsO4·7H2O). The treatment of As reduced plant biomass (24.4%) and chlorophyll a (51.7%), chlorophyll b (25.9%), while it increased subcellular As in roots and leaves, levels of glutathione (GSH), hydrogen peroxide (H2O2), malondialdehyde (MDA), methylglyoxal (MG), H2S and phytochelatins (PCs) in pepper plants. In As-stressed pepper plants, the application of MT increased plant biomass (16.3%), chlorophyll a (52.7%), chlorophyll b (28.2%), antioxidant enzymes' activities, and H2S accumulation, while it lowered the concentrations of MDA and H2O2. In As-treated plants, GSH and phytochelatins (PCs) were increased by MT by regulating As sequestration to make it harmless. The addition of MT increased As accumulation in the vacuoles of roots and caused the soluble fraction of As in vacuoles to become less toxic to vital organelles. MT-induced tolerance to As stress was further enhanced using NaHS, a source of H2S. Hypotaurine (0.1 mM HT), a H2S scavenger, was applied to the control and As-stressed plants together with MT and MT + NaHS to determine whether H2S was implicated in MT-induced increased As-S tolerance. By reducing H2S generation in pepper plants, HT counteracted the beneficial effects of MT, whereas the addition of NaHS to MT + HT restored the negative effects of HT, proving that H2S is necessary for the pepper plants As-stress tolerance caused by MT.
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Affiliation(s)
- Cengiz Kaya
- Soil Science and Plant Nutrition Department, Harran University, Sanliurfa, Turkey.
| | - Ferhat Ugurlar
- Soil Science and Plant Nutrition Department, Harran University, Sanliurfa, Turkey
| | - Muhammed Ashraf
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
| | - Mohammed Nasser Alyemeni
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Andrzej Bajguz
- Department of Biology and Ecology of Plants, Faculty of Biology University of Bialystok, Konstantego Ciolkowskiego 1J, 15-245, Bialystok, Poland
| | - Parvaiz Ahmad
- Department of Botany, GDC Pulwama, 192301, Jammu and Kashmir, India.
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Sun C, Sun N, Ou Y, Gong B, Jin C, Shi Q, Lin X. Phytomelatonin and plant mineral nutrition. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5903-5917. [PMID: 35767844 DOI: 10.1093/jxb/erac289] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 06/29/2022] [Indexed: 05/27/2023]
Abstract
Plant mineral nutrition is critical for agricultural productivity and for human nutrition; however, the availability of mineral elements is spatially and temporally heterogeneous in many ecosystems and agricultural landscapes. Nutrient imbalances trigger intricate signalling networks that modulate plant acclimation responses. One signalling agent of particular importance in such networks is phytomelatonin, a pleiotropic molecule with multiple functions. Evidence indicates that deficiencies or excesses of nutrients generally increase phytomelatonin levels in certain tissues, and it is increasingly thought to participate in the regulation of plant mineral nutrition. Alterations in endogenous phytomelatonin levels can protect plants from oxidative stress, influence root architecture, and influence nutrient uptake and efficiency of use through transcriptional and post-transcriptional regulation; such changes optimize mineral nutrient acquisition and ion homeostasis inside plant cells and thereby help to promote growth. This review summarizes current knowledge on the regulation of plant mineral nutrition by melatonin and highlights how endogenous phytomelatonin alters plant responses to specific mineral elements. In addition, we comprehensively discuss how melatonin influences uptake and transport under conditions of nutrient shortage.
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Affiliation(s)
- Chengliang Sun
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, Hangzhou, PR China
| | - Nan Sun
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, Hangzhou, PR China
| | - Yiqun Ou
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, Hangzhou, PR China
| | - Biao Gong
- College of Horticulture Science and Engineering, Shandong Agricultural University, Taian, PR China
| | - Chongwei Jin
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, Hangzhou, PR China
| | - Qinghua Shi
- College of Horticulture Science and Engineering, Shandong Agricultural University, Taian, PR China
| | - Xianyong Lin
- MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental & Resource Sciences, Zhejiang University, Hangzhou, PR China
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Hassan MU, Mahmood A, Awan MI, Maqbool R, Aamer M, Alhaithloul HAS, Huang G, Skalicky M, Brestic M, Pandey S, El Sabagh A, Qari SH. Melatonin-Induced Protection Against Plant Abiotic Stress: Mechanisms and Prospects. FRONTIERS IN PLANT SCIENCE 2022; 13:902694. [PMID: 35755707 PMCID: PMC9218792 DOI: 10.3389/fpls.2022.902694] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 04/25/2022] [Indexed: 05/23/2023]
Abstract
Global warming in this century increases incidences of various abiotic stresses restricting plant growth and productivity and posing a severe threat to global food production and security. The plant produces different osmolytes and hormones to combat the harmful effects of these abiotic stresses. Melatonin (MT) is a plant hormone that possesses excellent properties to improve plant performance under different abiotic stresses. It is associated with improved physiological and molecular processes linked with seed germination, growth and development, photosynthesis, carbon fixation, and plant defence against other abiotic stresses. In parallel, MT also increased the accumulation of multiple osmolytes, sugars and endogenous hormones (auxin, gibberellic acid, and cytokinins) to mediate resistance to stress. Stress condition in plants often produces reactive oxygen species. MT has excellent antioxidant properties and substantially scavenges reactive oxygen species by increasing the activity of enzymatic and non-enzymatic antioxidants under stress conditions. Moreover, the upregulation of stress-responsive and antioxidant enzyme genes makes it an excellent stress-inducing molecule. However, MT produced in plants is not sufficient to induce stress tolerance. Therefore, the development of transgenic plants with improved MT biosynthesis could be a promising approach to enhancing stress tolerance. This review, therefore, focuses on the possible role of MT in the induction of various abiotic stresses in plants. We further discussed MT biosynthesis and the critical role of MT as a potential antioxidant for improving abiotic stress tolerance. In addition, we also addressed MT biosynthesis and shed light on future research directions. Therefore, this review would help readers learn more about MT in a changing environment and provide new suggestions on how this knowledge could be used to develop stress tolerance.
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Affiliation(s)
- Muhammad Umair Hassan
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang, China
| | - Athar Mahmood
- Department of Agronomy, University of Agriculture Faisalabad, Faisalabad, Pakistan
| | - Masood Iqbal Awan
- Department of Agronomy, Sub-Campus Depalpur, Okara, University of Agriculture Faisalabad, Faisalabad, Pakistan
| | - Rizwan Maqbool
- Department of Agronomy, University of Agriculture Faisalabad, Faisalabad, Pakistan
| | - Muhammad Aamer
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang, China
- Department of Agronomy, Sub-Campus Depalpur, Okara, University of Agriculture Faisalabad, Faisalabad, Pakistan
| | | | - Guoqin Huang
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang, China
| | - Milan Skalicky
- Department of Botany and Plant Physiology, Faculty of Agrobiology, Food, and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia
| | - Marian Brestic
- Department of Botany and Plant Physiology, Faculty of Agrobiology, Food, and Natural Resources, Czech University of Life Sciences Prague, Prague, Czechia
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovakia
| | - Saurabh Pandey
- Department of Agriculture, Guru Nanak Dev University, Amritsar, India
| | - Ayman El Sabagh
- Department of Agronomy, Faculty of Agriculture, Kafrelsheikh University, Kafr El-Sheikh, Egypt
- Department of Field Crops, Faculty of Agriculture, Siirt University, Siirt, Turkey
| | - Sameer H. Qari
- Department of Biology, Al-Jumum University College, Umm Al-Qura University, Makkah, Saudi Arabia
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Melatonin Alleviates Copper Toxicity via Improving ROS Metabolism and Antioxidant Defense Response in Tomato Seedlings. Antioxidants (Basel) 2022; 11:antiox11040758. [PMID: 35453443 PMCID: PMC9025625 DOI: 10.3390/antiox11040758] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/02/2022] [Accepted: 04/07/2022] [Indexed: 12/21/2022] Open
Abstract
The excessive accumulation of copper (Cu2+) has become a threat to worldwide crop production. Recently, it was revealed that melatonin (MT) could play a crucial role against heavy metal (HM) stresses in plants. However, the underlying mechanism of MT function acted upon by Cu2+ stress (CS) has not been substantiated in tomatoes. In the present work, we produced MT-rich tomato plants by foliar usage of MT, and MT-deficient tomato plants by employing a virus-induced gene silencing methodology and exogenous foliar application of MT synthesis inhibitor para-chlorophenylalanine (pCPA). The obtained results indicate that exogenous MT meaningfully alleviated the dwarf phenotype and impeded the reduction in plant growth caused by excess Cu2+. Furthermore, MT effectively restricted the generation of reactive oxygen species (ROS) and habilitated cellular integrity by triggering antioxidant enzyme activities, especially via CAT and APX, but not SOD and POD. In addition, MT increased nonenzymatic antioxidant activity, including FRAP and the GSH/GSSG and ASA/DHA ratios. MT usage improved the expression of several defense genes (CAT, APX, GR and MDHAR) and MT biosynthesis-related genes (TDC, SNAT and COMT). Taken together, our results preliminarily reveal that MT alleviates Cu2+ toxicity via ROS scavenging, enhancing antioxidant capacity when subjected to excessive Cu2+. These results build a solid foundation for developing new insights to solve problems related to CS.
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Zeng W, Mostafa S, Lu Z, Jin B. Melatonin-Mediated Abiotic Stress Tolerance in Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:847175. [PMID: 35615125 PMCID: PMC9125191 DOI: 10.3389/fpls.2022.847175] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 04/19/2022] [Indexed: 05/07/2023]
Abstract
Melatonin is a multi-functional molecule that is ubiquitous in all living organisms. Melatonin performs essential roles in plant stress tolerance; its application can reduce the harmful effects of abiotic stresses. Plant melatonin biosynthesis, which usually occurs within chloroplasts, and its related metabolic pathways have been extensively characterized. Melatonin regulates plant stress responses by directly inhibiting the accumulation of reactive oxygen and nitrogen species, and by indirectly affecting stress response pathways. In this review, we summarize recent research concerning melatonin biosynthesis, metabolism, and antioxidation; we focus on melatonin-mediated tolerance to abiotic stresses including drought, waterlogging, salt, heat, cold, heavy metal toxicity, light and others. We also examine exogenous melatonin treatment in plants under abiotic stress. Finally, we discuss future perspectives in melatonin research and its applications in plants.
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Affiliation(s)
- Wen Zeng
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
| | - Salma Mostafa
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
- Department of Floriculture, Faculty of Agriculture, Alexandria University, Alexandria, Egypt
| | - Zhaogeng Lu
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
- *Correspondence: Zhaogeng Lu,
| | - Biao Jin
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
- Biao Jin,
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Kaur G, Sharma P, Rathee S, Singh HP, Batish DR, Kohli RK. Salicylic acid pre-treatment modulates Pb 2+-induced DNA damage vis-à-vis oxidative stress in Allium cepa roots. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:51989-52000. [PMID: 33999323 DOI: 10.1007/s11356-021-14151-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
The current study investigated the putative role of salicylic acid (SA) in modulating Pb2+-induced DNA and oxidative damage in Allium cepa roots. Pb2+ exposure enhanced free radical generation and reduced DNA integrity and antioxidant machinery after 24 h; however, SA pre-treatment (for 24 h) ameliorated Pb2+ toxicity. Pb2+ exposure led to an increase in malondialdehyde (MDA) and hydrogen peroxide (H2O2) accumulation and enhanced superoxide radical and hydroxyl radical levels. SA improved the efficiency of enzymatic antioxidants (ascorbate and guaiacol peroxidases [APX, GPX], superoxide dismutases [SOD], and catalases [CAT]) at 50-μM Pb2+ concentration. However, SA pre-treatment could not improve the efficiency of CAT and APX at 500 μM of Pb2+ treatment. Elevated levels of ascorbate and glutathione were observed in A. cepa roots pre-treated with SA and exposed to 50 μM Pb2+ treatment, except for oxidized glutathione. Nuclear membrane integrity test demonstrated the ameliorating effect of SA by reducing the number of dark blue-stained nuclei as compared to Pb2+ alone treatments. SA was successful in reducing DNA damage in cell exposed to higher concentration of Pb2+ (500 μM) as observed through comet assay. The study concludes that SA played a major role in enhancing defense mechanism and protecting against DNA damage by acclimatizing the plant to Pb2+-induced toxicity.
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Affiliation(s)
- Gurpreet Kaur
- Department of Environment Studies, Panjab University, Chandigarh, 160 014, India
- Agriculture Victoria, AgriBio, The Centre for AgriBioscience, 5 Ring Road, Bundoora, Victoria, 3083, Australia
- School of Applied Systems Biology, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Padma Sharma
- Department of Environment Studies, Panjab University, Chandigarh, 160 014, India
| | - Sonia Rathee
- Department of Botany, Panjab University, Chandigarh, 160 014, India
| | - Harminder Pal Singh
- Department of Environment Studies, Panjab University, Chandigarh, 160 014, India.
| | - Daizy Rani Batish
- Department of Botany, Panjab University, Chandigarh, 160 014, India.
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Abbas F, Ke Y, Zhou Y, Yu Y, Waseem M, Ashraf U, Li X, Yu R, Fan Y. Genome-wide analysis of ARF transcription factors reveals HcARF5 expression profile associated with the biosynthesis of β-ocimene synthase in Hedychium coronarium. PLANT CELL REPORTS 2021. [PMID: 34052884 DOI: 10.1007/s00299021-02709-2701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Herein, 37 ARF genes were identified and analyzed in Hedychium coronarium and HcARF5 showed a potential role in the regulation of HcTPS3. Auxin is an important plant hormone, implicated in various aspects of plant growth and development processes especially in the biosynthesis of various secondary metabolites. Auxin response factors (ARF) belong to the transcription factors (TFs) gene family and play a crucial role in transcriptional activation/repression of auxin-responsive genes by directly binding to their promoter region. Nevertheless, whether ARF genes are involved in the regulatory mechanism of volatile compounds in flowering plants is largely unknown. β-ocimene is a key floral volatile compound synthesized by terpene synthase 3 (HcTPS3) in Hedychium coronarium. A comprehensive analysis of H. coronarium genome reveals 37 candidate ARF genes in the whole genome. Tissue-specific expression patterns of HcARFs family members were assessed using available transcriptome data. Among them, HcARF5 showed a higher expression level in flowers, and significantly correlated with the key structural β-ocimene synthesis gene (HcTPS3). Furthermore, transcript levels of both genes were associated with the flower development. Under hormone treatments, the response of HcARF5 and HcTPS3, and the emission level of β-ocimene contents were evaluated. Subcellular and transcriptional activity assay showed that HcARF5 localizes to the nucleus and possesses transcriptional activity. Yeast one-hybrid (Y1H) and dual-luciferase assays revealed that HcARF5 directly regulates the transcriptional activity of HcTPS3. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that HcARF5 interacts with scent-related HcIAA4, HcIAA6, and HcMYB1 in vivo. Overall, these results indicate that HcARF5 is potentially involved in the regulation of β-ocimene synthesis in H. coronarium.
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Affiliation(s)
- Farhat Abbas
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Yanguo Ke
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
- College of Economics and Management, Kunming University, Kunming, 650214, China
| | - Yiwei Zhou
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Yunyi Yu
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Muhammad Waseem
- College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
| | - Umair Ashraf
- Department of Botany, Division of Science and Technology, University of Education, Lahore, 54770, Punjab, Pakistan
| | - Xinyue Li
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Rangcai Yu
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yanping Fan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, 510642, China.
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Shen J, Chen D, Zhang X, Song L, Dong J, Xu Q, Hu M, Cheng Y, Shen F, Wang W. Mitigation of salt stress response in upland cotton (Gossypium hirsutum) by exogenous melatonin. JOURNAL OF PLANT RESEARCH 2021; 134:857-871. [PMID: 33763804 DOI: 10.1007/s10265-021-01284-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 03/16/2021] [Indexed: 05/23/2023]
Abstract
As a pleiotropic signal molecule, melatonin is ubiquitous throughout the animal and plant kingdoms and plays important roles in the regulation of plant growth, development, and responses to environmental stresses. In this study, we quantified the endogenous melatonin levels in upland cotton (Gossypium hirsutum L.), using high-performance liquid chromatography-tandem mass spectrometry. The melatonin concentrations in root, stem, and leaf were 150.60, 37.92, and 40.58 ng g fresh weight- 1, respectively. The effects of exogenous melatonin (1 µM) on plant growth, photosynthesis, antioxidant enzyme activity, and ion homeostasis in upland cotton seedlings exposed to 100 mM NaCl treatment were determined. Pretreatment (prior to exposure to salt stress) of seedlings with exogenous melatonin significantly alleviated plant growth inhibition by salt stress and maintained an improved photosynthetic capacity. The application of melatonin also significantly reduced the salt-induced oxidative damage, possibly through the accumulation of osmotic regulatory substances and the activation of antioxidant enzymes. We also showed that exogenous melatonin regulated the expression of stress-responsive and ion-channel genes under salinity, which could contribute to improved salt tolerance in cotton. Taken together, our study provides evidence that cotton contains endogenous melatonin, and it may have unraveled crucial evidence of the role of melatonin in cotton against salt stress.
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Affiliation(s)
- Jian Shen
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Dongdong Chen
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Xiaopei Zhang
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Lirong Song
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Jie Dong
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Qingjiang Xu
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Mengjiao Hu
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Yingying Cheng
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Fafu Shen
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Wei Wang
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
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15
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Abbas F, Ke Y, Zhou Y, Yu Y, Waseem M, Ashraf U, Li X, Yu R, Fan Y. Genome-wide analysis of ARF transcription factors reveals HcARF5 expression profile associated with the biosynthesis of β-ocimene synthase in Hedychium coronarium. PLANT CELL REPORTS 2021; 40:1269-1284. [PMID: 34052884 DOI: 10.1007/s00299-021-02709-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/28/2021] [Indexed: 05/19/2023]
Abstract
Herein, 37 ARF genes were identified and analyzed in Hedychium coronarium and HcARF5 showed a potential role in the regulation of HcTPS3. Auxin is an important plant hormone, implicated in various aspects of plant growth and development processes especially in the biosynthesis of various secondary metabolites. Auxin response factors (ARF) belong to the transcription factors (TFs) gene family and play a crucial role in transcriptional activation/repression of auxin-responsive genes by directly binding to their promoter region. Nevertheless, whether ARF genes are involved in the regulatory mechanism of volatile compounds in flowering plants is largely unknown. β-ocimene is a key floral volatile compound synthesized by terpene synthase 3 (HcTPS3) in Hedychium coronarium. A comprehensive analysis of H. coronarium genome reveals 37 candidate ARF genes in the whole genome. Tissue-specific expression patterns of HcARFs family members were assessed using available transcriptome data. Among them, HcARF5 showed a higher expression level in flowers, and significantly correlated with the key structural β-ocimene synthesis gene (HcTPS3). Furthermore, transcript levels of both genes were associated with the flower development. Under hormone treatments, the response of HcARF5 and HcTPS3, and the emission level of β-ocimene contents were evaluated. Subcellular and transcriptional activity assay showed that HcARF5 localizes to the nucleus and possesses transcriptional activity. Yeast one-hybrid (Y1H) and dual-luciferase assays revealed that HcARF5 directly regulates the transcriptional activity of HcTPS3. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that HcARF5 interacts with scent-related HcIAA4, HcIAA6, and HcMYB1 in vivo. Overall, these results indicate that HcARF5 is potentially involved in the regulation of β-ocimene synthesis in H. coronarium.
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Affiliation(s)
- Farhat Abbas
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Yanguo Ke
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
- College of Economics and Management, Kunming University, Kunming, 650214, China
| | - Yiwei Zhou
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Yunyi Yu
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Muhammad Waseem
- College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
| | - Umair Ashraf
- Department of Botany, Division of Science and Technology, University of Education, Lahore, 54770, Punjab, Pakistan
| | - Xinyue Li
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Rangcai Yu
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yanping Fan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, 510642, China.
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16
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Pardo-Hernández M, López-Delacalle M, Martí-Guillen JM, Martínez-Lorente SE, Rivero RM. ROS and NO Phytomelatonin-Induced Signaling Mechanisms under Metal Toxicity in Plants: A Review. Antioxidants (Basel) 2021; 10. [PMID: 34068211 DOI: 10.20944/preprints202104.0637.v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 05/20/2023] Open
Abstract
Metal toxicity in soils, along with water runoff, are increasing environmental problems that affect agriculture directly and, in turn, human health. In light of finding a suitable and urgent solution, research on plant treatments with specific compounds that can help mitigate these effects has increased, and thus the exogenous application of melatonin (MET) and its role in alleviating the negative effects of metal toxicity in plants, have become more important in the last few years. MET is an important plant-related response molecule involved in growth, development, and reproduction, and in the induction of different stress-related key factors in plants. It has been shown that MET plays a protective role against the toxic effects induced by different metals (Pb, Cd, Cu, Zn, B, Al, V, Ni, La, As, and Cr) by regulating both the enzymatic and non-enzymatic antioxidant plant defense systems. In addition, MET interacts with many other signaling molecules, such as reactive oxygen species (ROS) and nitric oxide (NO) and participates in a wide variety of physiological reactions. Furthermore, MET treatment enhances osmoregulation and photosynthetic efficiency, and increases the concentration of other important antioxidants such as phenolic compounds, flavonoids, polyamines (PAs), and carotenoid compounds. Some recent studies have shown that MET appeared to be involved in the regulation of metal transport in plants, and lastly, various studies have confirmed that MET significantly upregulated stress tolerance-related genes. Despite all the knowledge acquired over the years, there is still more to know about how MET is involved in the metal toxicity tolerance of plants.
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Affiliation(s)
- Miriam Pardo-Hernández
- Center of Edaphology and Applied Biology of Segura River-Spanish National Research Council (CEBAS-CSIC), Department of Plant Nutrition, Campus Universitario Espinardo, Ed. 25, 30100 Espinardo, Murcia, Spain
| | - María López-Delacalle
- Center of Edaphology and Applied Biology of Segura River-Spanish National Research Council (CEBAS-CSIC), Department of Plant Nutrition, Campus Universitario Espinardo, Ed. 25, 30100 Espinardo, Murcia, Spain
| | - José Manuel Martí-Guillen
- Center of Edaphology and Applied Biology of Segura River-Spanish National Research Council (CEBAS-CSIC), Department of Plant Nutrition, Campus Universitario Espinardo, Ed. 25, 30100 Espinardo, Murcia, Spain
| | - Sara E Martínez-Lorente
- Center of Edaphology and Applied Biology of Segura River-Spanish National Research Council (CEBAS-CSIC), Department of Plant Nutrition, Campus Universitario Espinardo, Ed. 25, 30100 Espinardo, Murcia, Spain
| | - Rosa M Rivero
- Center of Edaphology and Applied Biology of Segura River-Spanish National Research Council (CEBAS-CSIC), Department of Plant Nutrition, Campus Universitario Espinardo, Ed. 25, 30100 Espinardo, Murcia, Spain
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17
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Pardo-Hernández M, López-Delacalle M, Martí-Guillen JM, Martínez-Lorente SE, Rivero RM. ROS and NO Phytomelatonin-Induced Signaling Mechanisms under Metal Toxicity in Plants: A Review. Antioxidants (Basel) 2021; 10:antiox10050775. [PMID: 34068211 PMCID: PMC8153167 DOI: 10.3390/antiox10050775] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 01/01/2023] Open
Abstract
Metal toxicity in soils, along with water runoff, are increasing environmental problems that affect agriculture directly and, in turn, human health. In light of finding a suitable and urgent solution, research on plant treatments with specific compounds that can help mitigate these effects has increased, and thus the exogenous application of melatonin (MET) and its role in alleviating the negative effects of metal toxicity in plants, have become more important in the last few years. MET is an important plant-related response molecule involved in growth, development, and reproduction, and in the induction of different stress-related key factors in plants. It has been shown that MET plays a protective role against the toxic effects induced by different metals (Pb, Cd, Cu, Zn, B, Al, V, Ni, La, As, and Cr) by regulating both the enzymatic and non-enzymatic antioxidant plant defense systems. In addition, MET interacts with many other signaling molecules, such as reactive oxygen species (ROS) and nitric oxide (NO) and participates in a wide variety of physiological reactions. Furthermore, MET treatment enhances osmoregulation and photosynthetic efficiency, and increases the concentration of other important antioxidants such as phenolic compounds, flavonoids, polyamines (PAs), and carotenoid compounds. Some recent studies have shown that MET appeared to be involved in the regulation of metal transport in plants, and lastly, various studies have confirmed that MET significantly upregulated stress tolerance-related genes. Despite all the knowledge acquired over the years, there is still more to know about how MET is involved in the metal toxicity tolerance of plants.
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18
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Murch SJ, Erland LAE. A Systematic Review of Melatonin in Plants: An Example of Evolution of Literature. FRONTIERS IN PLANT SCIENCE 2021; 12:683047. [PMID: 34249052 PMCID: PMC8270005 DOI: 10.3389/fpls.2021.683047] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/10/2021] [Indexed: 05/06/2023]
Abstract
Melatonin (N-acetyl-5-methoxy-tryptamine) is a mammalian neurohormone, antioxidant and signaling molecule that was first discovered in plants in 1995. The first studies investigated plant melatonin from a human perspective quantifying melatonin in foods and medicinal plants and questioning whether its presence could explain the activity of some plants as medicines. Starting with these first handful of studies in the late 1990s, plant melatonin research has blossomed into a vibrant and active area of investigation and melatonin has been found to play critical roles in mediating plant responses and development at every stage of the plant life cycle from pollen and embryo development through seed germination, vegetative growth and stress response. Here we have utilized a systematic approach in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) protocols to reduce bias in our assessment of the literature and provide an overview of the current state of melatonin research in plants, covering 1995-2021. This review provides an overview of the biosynthesis and metabolism of melatonin as well as identifying key themes including: abiotic stress responses, root development, light responses, interkingdom communication, phytohormone and plant signaling. Additionally, potential biases in the literature are investigated and a birefringence in the literature between researchers from plant and medical based which has helped to shape the current state of melatonin research. Several exciting new opportunities for future areas of melatonin research are also identified including investigation of non-crop and non-medicinal species as well as characterization of melatonin signaling networks in plants.
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