Melatonin alleviates salt damage in tomato seedling: A root architecture system, photosynthetic capacity, ion homeostasis, and antioxidant enzymes analysis

Tomato is considered an important vegetable crop for studying the response to abiotic stresses, which deteriorate the growth and development of plants, particularly salt stress. Melatonin is a crucial pleiotropic nontoxic signaling molecule that has a various role in modulating of plant responses to environmental stresses. The purpose of the study was to reckon the alleviating effects of melatonin on tomato plant growth and development in salinity condition. The results exhibited that the pretreatment of tomato seedlings with 100 mu M melatonin for 3 days effectively improved the root architecture, photosynthetic pigments, photosynthetic assimilation and growth status of plants under subsequent salt stress (150 mM). The pretreatment slashed sodium ions concentration in leaf and stem by checking sodium ions transport from roots to shoot. Furthermore, melatonin notably surged potassium contents. Melatonin pretreatment (3 days) followed by salinity exposure (7 days) efficiently lowered the oxidative stress by checking the over accumulation of superoxide (O-2(center dot-)) and hydrogen peroxide (H2O2), reducing the malondialdehyde (MDA) content and electrolyte leakage (EL). This was associated with increased activities of enzymatic antioxidants [superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and ascorbate peroxidase (APX)] and non-enzymatic antioxidants [ascorbic acid (AsA) and glutathione (GSH)]. In conclusion, melatonin pretreatment significantly escalates the salinity tolerance of tomato seedlings by scavenging the excessive ROS and improving cellular membrane stability of, thus mitigating salinity-induced oxidative damage.

Automated summary

The study demonstrates that melatonin pretreatment significantly enhances the salt tolerance of tomato seedlings by improving root architecture, photosynthetic pigments, and overall growth status under salt stress. It also effectively reduces oxidative stress, inhibiting the accumulation of harmful substances and promoting enzymatic and non-enzymatic antioxidants activities to mitigate salinity-induced damage.