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Plant Science Today (PST)

Research Articles

Vol. 12 No. 4 (2025)

Influence of melatonin on salinity tolerance in cowpeas through mitigation of osmotic and oxidative stress

DOI
https://doi.org/10.14719/pst.11844
Submitted
18 September 2025
Published
19-11-2025 — Updated on 04-12-2025
Versions

Abstract

Biostimulators such as melatonin (MT), a plant stress-related phytohormone, enhance plant tolerance to salinity. Therefore, the present study aimed to investigate the ameliorative effects of MT on cowpea plants under salinity stress to determine its mechanism of action and potential application in sustainable agriculture. In this experiment, cowpea seedlings were irrigated with 150 mM NaCl and foliar-sprayed with 300 µM MT as a mitigative treatment. Growth, photosynthetic rate, sodium (Na+), potassium (K+), hydrogen peroxide (H2O2) and electrolyte leakage (EL) were measured to assess the effects of salinity and MT on cowpea performance. Additionally, osmolytes and both enzymatic and non-enzymatic antioxidants, were evaluated to elucidate the underlying mechanism of MT-mediated salinity mitigation. This study provides the first experimental evidence that 300 µM MT significantly improves cowpea growth and physiological responses under salinity stress. The results showed that plant height and leaf area increased by 32.4  % and 39.4  %, respectively, while fresh and dry weights exhibited only slight improvements. MT application enhanced photosynthesis by 29.4  % and increased anthocyanin content by 37.3  %. Furthermore, MT reduced Na⁺ concentration by about 60  %, lowered EL by 22  % and decreased H2O2 levels by 67.4  %. Although potassium levels were unaffected, MT reduced catalase (CAT) activity by 30.6  %. Lastly, total flavonoids increased by 12.1  % under salt stress. Therefore, MT enhances cowpea salinity tolerance by improving photosynthesis, antioxidant defense and ion homeostasis, thereby reducing oxidative damage and serving as an effective biostimulator for cowpeas cultivated under salinity conditions. These findings underscore the potential of MT-enriched bioformulations or organic fertilizers in enhancing crop productivity under salt-affected soils.

References

  1. 1. Khattab HI, Sadak MS, Dawood MG, Elkady FM, Helal NM. Foliar application of esculin and digitoxin improve the yield quality of salt-stressed Linum usitatissimum by improving the antioxidant defense system. BMC Plant Biol. 2024;24(1):963. https://doi.org/10.1186/s12870-024-05626-z
  2. 2. Abebe BK, Alemayehu MT. A review of the nutritional use of cowpea (Vigna unguiculata L. Walp) for human and animal diets. J Agric Food Res. 2022;10:100383. https://doi.org/10.1016/j.jafr.2022.100383
  3. 3. Mini M, Sathya M, Arulvadivookarasi K, Jayachandran K, Anusuyadevi M. Selection of salt tolerant cowpea genotypes based on salt tolerant indices of morpho-biochemical traits. Curr Trends Biotechnol Pharm. 2015;9:306-16.
  4. 4. Zhou H, Shi H, Yang Y, Feng X, Chen X, Xiao F, et al. Insights into plant salt stress signalling and tolerance. J Genet Genomics. 2024;51(1):16-34. https://doi.org/10.1016/j.jgg.2023.08.007
  5. 5. Hu Y, Wang D, Zhang X, Lv X, Li B. Current progress in deciphering the molecular mechanisms underlying plant salt tolerance. Curr Opin Plant Biol. 2025;83:102671. https://doi.org/10.1016/j.pbi.2024.102671
  6. 6. Jiang L, Xiao M, Huang R, Wang J. The regulation of ROS and phytohormones in balancing crop yield and salt tolerance. Antioxidants. 2025;14(1):63. https://doi.org/10.3390/antiox14010063
  7. 7. Al Kharusi L, Al Yahyai R, Yaish MW. Antioxidant response to salinity in salt-tolerant and salt-susceptible cultivars of date palm. Agriculture. 2019;9(1):8. https://doi.org/10.3390/agriculture9010008
  8. 8. Sadak MS, Ramadan AAE-M. Impact of melatonin and tryptophan on water stress tolerance in white lupine (Lupinus termis L.). Physiol Mol Biol Plants. 2021;27(3):469-81. https://doi.org/10.1007/s12298-021-00958-8
  9. 9. Faizan M, Sultan H, Alam P, Karabulut F, Cheng S-H, Rajput VD, et al. Melatonin and its cross-talk with other signalling molecules under abiotic stress. Plant Stress. 2024;11:100410. https://doi.org/10.1016/j.stress.2024.100410
  10. 10. Arnao MB, Hernández-Ruiz J. Melatonin as a chemical substance or as phytomelatonin-rich extracts for use as plant protector and/or biostimulant in accordance with EC legislation. Agronomy. 2019;9(10):570. https://doi.org/10.3390/agronomy9100570
  11. 11. Rajendra F, Kristiani L, Ariviani S, editors. Elicitation under salinity stress increases flavonoid content and antioxidant activity in cowpea (Vigna unguiculata) sprouts. In: IOP Conference Series: Materials Science and Engineering; 2019: IOP Publishing. https://doi.org/10.1088/1757-899X/633/1/012034
  12. 12. Porra RJ, Thompson WA, Kriedemann PE. Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: Verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. Biochim Biophys Acta (BBA)-Bioenergetics. 1989;975(3):384-94. https://doi.org/10.1016/S0005-2728(89)80347-0
  13. 13. Munns R, Wallace PA, Teakle NL, Colmer TD. Measuring soluble ion concentrations (Na+, K+, Cl-) in salt-treated plants. In: Methods in Molecular Biology. Humana Press; 2010. p. 371-82. https://doi.org/10.1007/978-1-60761-702-0_23
  14. 14. Assaha DV, Liu L, Ueda A, Nagaoka T, Saneoka H. Effects of drought stress on growth, solute accumulation and membrane stability of leafy vegetable, huckleberry (Solanum scabrum Mill.). J Environ Biol. 2016;37(1):107-14.
  15. 15. Alexieva V, Sergiev I, Mapelli S, Karanov E. The effect of drought and ultraviolet radiation on growth and stress markers in pea and wheat. Plant Cell Environ. 2001;24(12):1337-44. https://doi.org/10.1046/j.1365-3040.2001.00778.x
  16. 16. Yan F, Wei H, Ding Y, Li W, Liu Z, Chen L, et al. Melatonin regulates antioxidant strategy in response to continuous salt stress in rice seedlings. Plant Physiol Biochem. 2021;165:239-50. https://doi.org/10.1016/j.plaphy.2021.06.031
  17. 17. Nakano Y, Asada K. Hydrogen peroxide is scavenged by ascorbate-specific peroxidase in spinach chloroplasts. Plant Cell Physiol. 1981;22(5):867-80. https://doi.org/10.1093/oxfordjournals.pcp.a076232
  18. 18. Wieland T, Pfleiderer G. Isozymes and heteroenzymes. Angew Chem Int Ed Engl. 1962;1(4):169-78.
  19. 19. Beauchamp C, Fridovich I. Superoxide dismutase: improved assays and an assay applicable to acrylamide gels. Anal Biochem. 1971;44(1):276-87.
  20. 20. Ahmad S, Cui W, Kamran M, Ahmad I, Meng X, Wu X, et al. Exogenous application of melatonin induces tolerance to salt stress by improving the photosynthetic efficiency and antioxidant defense system of maize seedling. J Plant Growth Regul. 2020;40(3):1270-83. https://doi.org/10.1007/s00344-020-10245-2
  21. 21. Lamaison J, Carant A. The amount of main flavonoids in flowers and leaves of Crataegus monogyna Jacq. and Crataegus laevigata (Poir.) DC. (Rosacea). Pharm Acta Helv. 1996;65:315-20.
  22. 22. Singleton VL, Orthofer R, Lamuela-Raventós RM. Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. In: Methods in Enzymology. 1999;299:152-78.
  23. 23. Loewus MW, Briggs D. The number of catalytically active sites present on the chymotrypsin molecule. J Biol Chem. 1952;199(2):857-64.
  24. 24. Bates LS, Waldren R, Teare I. Rapid determination of free proline for water-stress studies. Plant Soil. 1973;39:205-7. https://doi.org/10.1007/BF00018060
  25. 25. Al Khatri ISH, Ali HE, Yaish M. Melatonin improves drought tolerance in cowpea through growth modulation, antioxidant response and ionic homeostasis, supporting sustainable agriculture. Environ Res Commun. 2025;7:055019. https://doi.org/10.1088/2515-7620/add85f
  26. 26. Park H-S, Kazerooni EA, Kang S-M, Al-Sadi AM, Lee I-J. Melatonin enhances the tolerance and recovery mechanisms in Brassica juncea (L.) Czern. under saline conditions. Front Plant Sci. 2021;12:593717. https://doi.org/10.3389/fpls.2021.593717
  27. 27. ElSayed AI, Rafudeen MS, Gomaa AM, Hasanuzzaman M. Exogenous melatonin enhances the reactive oxygen species metabolism, antioxidant defense-related gene expression and photosynthetic capacity of Phaseolus vulgaris L. to confer salt stress tolerance. Physiol Plant. 2021;173(4):1369-81. https://doi.org/10.1111/ppl.13385
  28. 28. Sadak MS, Dawood MG. Biofertilizer role in alleviating the deleterious effects of salinity on wheat growth and productivity. Gesunde Pflanzen. 2023;75(4):1207-19. https://doi.org/10.1007/s10343-022-00653-4
  29. 29. Kamiab F. Exogenous melatonin mitigates the salinity damages and improves the growth of pistachio (Pistacia vera) under salinity stress. J Plant Nutr. 2020;43(10):1468-84. https://doi.org/10.1080/01904167.2019.1627353
  30. 30. Zhang N, Zhao B, Zhang H J, Weeda S, Yang C, Yang Z C, et al. Melatonin promotes water-stress tolerance, lateral root formation and seed germination in cucumber (Cucumis sativus L.). J Pineal Res. 2013;54(1):15-29. https://doi.org/10.1111/jpi.12018
  31. 31. Adil M, Abbasi BH, Khan T. Interactive effects of melatonin and light on growth parameters and biochemical markers in adventitious roots of Withania somnifera L. Plant Cell Tissue Organ Cult. 2015;123:405-12. https://doi.org/10.1007/s11240-015-0834‐1
  32. 32. El-Taher AM, El-Raouf A, Hany S, Osman NA, Azoz SN, Omar MA, et al. Effect of salt stress and foliar application of salicylic acid on morphological, biochemical, anatomical and productivity characteristics of cowpea (Vigna unguiculata L.) plants. Plants. 2022;11(1):115. https://doi.org/10.3390/plants11010115
  33. 33. Zhang N, Sun Q, Li H, Li X, Cao Y, Zhang H, et al. Melatonin improved anthocyanin accumulation by regulating gene expressions and resulted in high reactive oxygen species scavenging capacity in cabbage. Front Plant Sci. 2016;7:197. https://doi.org/10.3389/fpls.2016.00197
  34. 34. Sun H, Cao X, Wang X, Zhang W, Li W, Wang X, et al. RBOH-dependent hydrogen peroxide signalling mediates melatonin-induced anthocyanin biosynthesis in red pear fruit. Plant Sci. 2021;313:111093. https://doi.org/10.1016/j.plantsci.2021.111093
  35. 35. Zahedi SM, Hosseini MS, Fahadi Hoveizeh N, Gholami R, Abdelrahman M, Tran LSP. Exogenous melatonin mitigates salinity-induced damage in olive seedlings by modulating ion homeostasis, antioxidant defense and phytohormone balance. Physiol Plant. 2021;173(4):1682-94. https://doi.org/10.1111/ppl.13398
  36. 36. Azizi F, Amiri H, Ismaili A. Melatonin improves salinity stress tolerance of Phaseolus vulgaris L. cv. Pak by changing antioxidant enzymes and photosynthetic parameters. Acta Physiol Plant. 2022;44(4):40. https://doi.org/10.1007/s11738-022-03106-w
  37. 37. Siddiqui MH, Alamri S, Al-Khaishany MY, Khan MN, Al-Amri A, Ali HM, et al. Exogenous melatonin counteracts NaCl-induced damage by regulating the antioxidant system, proline and carbohydrates metabolism in tomato seedlings. Int J Mol Sci. 2019;20(2):353. https://doi.org/10.3390/ijms20020353
  38. 38. Ouerghi Z, Cornic G, Roudani M, Ayadi A, Brulfert J. Effect of NaCl on photosynthesis of two wheat species (Triticum durum and T. aestivum) differing in their sensitivity to salt stress. J Plant Physiol. 2000;156(3):335-40. https://doi.org/10.1016/S0176-1617(00)80071-1
  39. 39. Wilson C, Liu X, Lesch SM, Suarez DL. Growth response of major USA cowpea cultivars: II. Effect of salinity on leaf gas exchange. Plant Sci. 2006;170(6):1095-101. https://doi.org/10.1016/j.plantsci.2006.03.029
  40. 40. Abbas K, Li J, Gong B, Lu Y, Wu X, Lü G, et al. Drought stress tolerance in vegetables: the functional role of structural features, key gene pathways and exogenous hormones. Int J Mol Sci. 2023;24(18):13876. https://doi.org/10.3390/ijms241813876
  41. 41. Yan F, Zhang J, Li W, Ding Y, Zhong Q, Xu X, et al. Exogenous melatonin alleviates salt stress by improving leaf photosynthesis in rice seedlings. Plant Physiol Biochem. 2021;163:367-75. https://doi.org/10.1016/j.plaphy.2021.05.016
  42. 42. Taffouo VD, Kouamou JK, Ngalangue LT, Ndjeudji BAN, Akoa A. Effects of salinity stress on growth, ions partitioning and yield of some cowpea (Vigna unguiculata L. Walp.) cultivars. Int J Bot. 2009;5(2):135-43. 10.3923/ijb.2009.135.143
  43. 43. Salih HO, Kia DR. Effect of salinity level of irrigation water on cowpea (Vigna unguiculata) growth. J Agric Veter Sci. 2013;6(3):37-41.
  44. 44. Lacerda CF, Assis Júnior JO, Lemos Filho LC, Oliveira TSd, Guimarães FV, Gomes-Filho E, et al. Morpho-physiological responses of cowpea leaves to salt stress. Braz J Plant Physiol. 2006;18:455-65. https://doi.org/10.1590/S1677-04202006000400007
  45. 45. Ali M, Kamran M, Abbasi GH, Saleem MH, Ahmad S, Parveen A, et al. Melatonin-induced salinity tolerance by ameliorating osmotic and oxidative stress in the seedlings of two tomato (Solanum lycopersicum L.) cultivars. J Plant Growth Regul. 2021;40:2236-48. https://doi.org/10.1007/s00344-021-10384-2
  46. 46. Wang L, Liu J, Wang W, Sun Y. Exogenous melatonin improves growth and photosynthetic capacity of cucumber under salinity-induced stress. Photosynthetica. 2016;54:19-27. https://doi.org/10.1007/s11099-015-0199-7
  47. 47. Zhao J, Hu J. Melatonin: current status and future perspectives in horticultural plants. Front Plant Sci. 2023;14:1140803. https://doi.org/10.3389/fpls.2023.1140803
  48. 48. Jayawardhane J, Goyali JC, Zafari S, Igamberdiev AU. The response of cowpea (Vigna unguiculata) plants to three abiotic stresses applied with increasing intensity: hypoxia, salinity and water deficit. Metabolites. 2022;12(1):38. https://doi.org/10.3390/metabo12010038
  49. 49. Praxedes SC, Damatta FM, Lacerda CF, Prisco JT, Gomes-Filho E. Salt stress tolerance in cowpea is poorly related to the ability to cope with oxidative stress. Acta Bot Croat. 2014;73(1):51-62. https://doi.org/10.3989/abot.37313
  50. 50. Chen YE, Mao JJ, Sun LQ, Huang B, Ding CB, Gu Y, et al. Exogenous melatonin enhances salt stress tolerance in maize seedlings by improving antioxidant and photosynthetic capacity. Physiol Plant. 2018;164(3):349-63. https://doi.org/10.1111/ppl.12773
  51. 51. Liu T, Xing G, Chen Z, Zhai X, Wei X, Wang C, et al. Effect of exogenous melatonin on salt stress in cucumber: alleviating effect and molecular basis. Biotechnol Biotechnol Equip. 2022;36(1):818-27. https://doi.org/10.1080/13102818.2022.2105581

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