Antioxidant Machinery and Glyoxalase System Regulation Confers Salt Stress Tolerance to Wheat (Triticum aestivum L.) Plants Treated with Melatonin and Salicylic Acid

Abstract

Plant growth regulators melatonin (MT) and salicylic acid (SA) have potent roles in plant salt tolerance. However, only a few reports have studied the influence of their combined treatment on plant salt tolerance. The current study, as a first investigation, was aimed to evaluate the effect of MT and SA combined treatment on the antioxidant and glyoxalase defense machineries of salt-stressed wheat plants. In the present study, the potential role of 70 μM MT and/or 75 mg l−1 SA on mitigating salt injury (6.0 and 12.0 dS m−1 salinity levels) was investigated in wheat (Triticum aestivum L. cv. Sids 14). Exogenously applied MT and/or SA improved the activity of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, glutathione peroxidase, and glutathione S-transferase, which effectively scavenged reactive oxygen species (ROS) in stressed plants. Excessive accumulation of the toxic methylglyoxal was reversed via the up-regulation of the glyoxalase system (glyoxalase I and glyoxalase II) and the ascorbate–glutathione cycle. Foliar applications also reduced membrane damage by lowering lipid peroxidation and protein oxidation due to effective ROS detoxification by antioxidants such as ascorbate, glutathione, phenols, and flavonoids. Moreover, exogenous MT and/or SA applications increased endogenous MT and SA levels under both non-saline and saline conditions. The combined treatment of MT and SA yielded the best results. Overall, this combined treatment regulated the antioxidant machinery and glyoxalase system, suggesting a role for it in salt stress mitigation. Therefore, it can be considered as an effective method for reducing salt toxicity in sustainable agricultural systems.

A Novel Plant Growth–Promoting Agent Mitigates Salt Toxicity in Barley (Hordeum vulgare L.) by Activating Photosynthetic, Antioxidant Defense, and Methylglyoxal Detoxification Machineries

“…Salt stress can also induce oxidative stress by MG overproduction (Kamran et al 2020;Talaat and Todorova 2022). Consistent with this report, our study indicated a significant increase in barley MG content under 6.0 and 12.0 dS m −1 salinity levels.…”

“…Various antioxidative strategies have been developed in plants to cope with the oxidative stress induced by salinity. Previous studies suggested that plant salt tolerance was normally associated with plant antioxidative capacity, namely ROS-scavenging or-detoxification ability (Talaat 2019b;Talaat and Todorova 2022). Our results revealed that when barley plants facing the oxidative injury caused by salt stress, change in the antioxidant enzymes activity was detected.…”

“…Plants possess integrated machinery for ROS detoxification, which can be categorized into antioxidant enzymes (superoxide dismutase (SOD), guaiacol peroxidase (GPOX), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), monodehydroascorbate reductase (MDHAR), dehydroascorbate (DHAR)) and non-enzymatic antioxidants (α-tocopherol, carotenoids, ascorbic acid (AsA), reduced glutathione (GSH), flavonoids, total phenols) (Fan et al 2016;Todorova et al 2016). Another adverse effect of salt stress on plants is the accumulation of methylglyoxal (MG) which is very reactive cytotoxic compound (Nisarga et al 2017;Talaat and Todorova 2022). To eliminate excessive MG, a GSH-dependent glyoxalase system, including glyoxalase I (Gly I) and glyoxalase II (Gly II) has evolved in plant cells (Kamran et al 2020;Talaat and Todorova 2022).…”

“…Another adverse effect of salt stress on plants is the accumulation of methylglyoxal (MG) which is very reactive cytotoxic compound (Nisarga et al 2017;Talaat and Todorova 2022). To eliminate excessive MG, a GSH-dependent glyoxalase system, including glyoxalase I (Gly I) and glyoxalase II (Gly II) has evolved in plant cells (Kamran et al 2020;Talaat and Todorova 2022).…”

Enhancement of the Expression of ZmBZR1 and ZmBES1 Regulatory Genes and Antioxidant Defense Genes Triggers Water Stress Mitigation in Maize (Zea mays L.) Plants Treated with 24-Epibrassinolide in Combination with Spermine

“…Plant hormones are critical for plant growth and development because they orchestrate intrinsic developmental programs as well as relay environmental stimuli [15][16][17]. Among them, brassinosteroids (BRs), a group of steroidal phytohormones, regulate a variety of plant physiological processes such as cell division, cell elongation, seed germination, stomata development, vascular differentiation, plant architecture, flowering, senescence, and abiotic stress responses [18][19][20].…”