Exogenous melatonin enhances salt stress tolerance in tomato seedlings

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) is an essential molecule which regulates plant growth and development and alleviates the damaging effects of abiotic stresses. To evaluate the important functions of melatonin in response to salinity stress, the effects of exogenous melatonin on the antioxidant system and growth of tomato (Solanum lycopersicum L.) under 150 mM NaCl stress were investigated. The application of 100 μM melatonin compensated the growth inhibition caused by salt-stress. Melatonin treated seedlings had an increased fresh and dry masses of shoots and roots. The application of 1-200 µM melatonin notably enhanced the relative chlorophyll content (SPAD index), root characteristics, and gas exchange in tomato seedlings subjected to salt stress compared to seedlings treated with salt stress alone. Moreover, melatonin pretreatment minimized accumulation of reactive oxygen species and improved activities of antioxidative enzymes including catalase, superoxide dismutase, glutathione reductase, and ascorbate peroxidase.

Exogenous melatonin on Physiological and Yield Traits of Cassava (Manihot esculenta Crantz) under Salt Stress

“…An increase per cent of 33.98 was observed in the best melatonin treatment over the salt-stressed plants. In line with our results the pretreated tomato seeds exposed to salt stress condition had enhanced soluble protein content (Altaf et al, 2020). Similarly, Yin et al (2019) reported increased leaf soluble protein content on exogenous application of melatonin at low concentration.…”

“…Thus exogenous melatonin exhibits a major role in ROS reduction and increases antioxidants and secondary metabolites (Shakhawat et al, 2020;Shakeel et al, 2020). Altaf et al (2020), in tomato seedlings under salt stress, discovered the increase in gas exchange parameters when treated with melatonin. suggested that melatonin-treated plants had higher osmolyte contents, so the osmotic potential was lower compared to control.…”

Melatonin Improves Drought Stress Tolerance of Tomato by Modulating Plant Growth, Root Architecture, Photosynthesis, and Antioxidant Defense System

“…Conversely, tomato roots pretreated with ME evidently enhanced root characteristics ( Figure 4 ) contributing to better growth of tomato plants. Similarly, Altaf et al [ 33 ] revealed that melatonin application dominantly enhanced the root architecture system of tomato seedling under NaCl stress. Moreover, the positive relationship between the ME application and root growth has been well-known in S. lycopersicum [ 17 ], Citrullus lanatus [ 49 ], and Stevia rebaudiana [ 50 ] under abiotic stresses.…”

“…The treatment plan was implemented after ten days, when the seedlings were attained at the four-true-leaf stage. The treatments are followed in the current study including: (1) CK (control) treatment included the seedlings with full water application during the complete span of the experiment, (2) DR (drought) treatment included the plants which were first given water fully for eight days, followed by up to two weeks’ water-withholding, (3) ME + DR (melatonin + drought) was the treatment in which ME pretreatment was given to seedlings with 100 μM solution of ME (80 mL per plant) [ 33 ]. This pretreatment continued four times, with a 2-days’ interval, followed by up to two weeks’ water-withholding.…”

Vanadium Toxicity Induced Changes in Growth, Antioxidant Profiling, and Vanadium Uptake in Pepper (Capsicum annum L.) Seedlings

“…Roots of five similar plants (from each replication) were taken and rinsed with running tap water for root measurement. The root was scanned using an Imagery Scan Screen (Epson Expression 11000XL, Regent Instruments, Chemin Sainte-Foy, QC, Canada), and the root traits were determined using WinRHIZO 2003a software [25].…”