Inhospitable conditions that hinder plant growth and development encompass a range of abiotic stresses, such as drought, extreme temperatures (both low and high), salinity, exposure to heavy metals, and irradiation. The cumulative impact of these stresses leads to a considerable reduction in agricultural productivity worldwide. The generation of reactive oxygen species (ROS) is a shared mechanism of toxicity induced by all these abiotic stimuli in plants, resulting in oxidative damage and membrane instability. Extensive research has shed light on the dual role of melatonin in plants, where it serves as both a growth regulator, fostering growth and development, and a potent protector against abiotic stresses. The inherent potential of melatonin to function as a natural antioxidant positions it as a promising biostimulant for agricultural use, bolstering plants’ abilities to withstand a wide array of environmental challenges. Beyond its antioxidant properties, melatonin has demonstrated its capacity to regulate the expression of genes associated with the photosynthetic process. This additional characteristic enhances its appeal as a versatile chemical agent that can be exogenously applied to plants, particularly in adverse conditions, to improve their resilience and optimize photosynthetic efficiency in every phase of the plant life cycle. An examination of the molecular mechanisms underlying the stress-protective effects of exogenous melatonin on the photosynthetic machinery of plants under various abiotic stresses is presented in this paper. In addition, future prospects are discussed for developing stress-tolerant crops for sustainable agriculture in challenging environments.

With the growing global population, abiotic factors have emerged as a formidable threat to agricultural food production. If left unaddressed, these stress factors might reduce food yields by up to 25% by 2050. Plants utilize natural mechanisms, such as reactive oxygen species scavenging, to mitigate the adverse impacts of abiotic stressors. Diverse plants exhibit unique adaptations to abiotic stresses, which are regulated by phytohormones at various levels. Brassinosteroids (BRs) play a crucial role in controlling essential physiological processes in plants, including seed germination, xylem differentiation, and reproduction. The BR cascade serves as the mechanism through which plants respond to environmental stimuli, including drought and extreme temperatures. Despite two decades of research, the complex signaling of BRs under different stress conditions is still being elucidated. Manipulating BR signaling, biosynthesis, or perception holds promise for enhancing crop resilience. This review explores the role of BRs in signaling cascades and summarizes their substantial contribution to plants’ ability to withstand abiotic stresses.

This study aimed to assess the effects of low-temperature stress on two tomato cultivars (S-22 and PKM-1) treated with 24-epibrassinolide (EBL) and selenium (Se) by determining the changes in the proteomics profiles, growth biomarkers, biochemical parameters, and physiological functions. The growth parameters, photosynthetic traits, and activity of nitrate reductase in the S-22 and PKM-1 plants were markedly reduced by exposure to low temperatures. However, the combined application of EBL and Se under different modes significantly enhanced the aforementioned parameters under stress and non-stress conditions. Exposure to low temperatures increased the activities of the antioxidant enzymes (catalase, peroxidase, and superoxide dismutase) and the proline content of leaves, which were further enhanced by treatment with Se and EBL in both varieties. This research sheds light on the potential for employing exogenous EBL and Se as crucial biochemical tactics to assist tomato plants in surviving low-temperature stress. Moreover, the differentially expressed proteins that were involved in plant metabolism following the combined application of EBL and Se under low-temperature stress were additionally identified. Functional analysis revealed that the Q54YH4 protein plays an active role against plant stressors. The conserved regions in the protein sequences were analyzed for assessing the reliability of plant responses against the external application of EBL and Se under low temperatures.

Climate change-driven abiotic and biotic stresses are emerging as a major threat to crop productivity and global food security. Consequently, there is a great need to develop effective and ecologically sustainable strategies to augment the growth, development, and yield of crop plants, especially under adverse environmental conditions. Nanoparticle-mediated precise modulation of soil-plant interactions has emerged as an eco-friendly, biocompatible, and stimulus-responsive strategy to increase crop production by ameliorating abiotic and biotic stresses. Selenium (Se), a trace element, has emerged as a promising mitigator of diverse stresses, including heavy metal toxicity, salinity, drought, pathogens, and pests. The use of selenium nanoparticles (SeNPs) has emerged as a potential strategy to enhance plant stress resilience, due to their increased biocompatibility, reduced toxicity, and greater stability, which provide advantages over inorganic forms of Se. SeNPs are readily absorbed by plants through root hairs and thereby improve plant growth, regulate physiological processes, stimulate antioxidants and redox balance, upregulate stress-responsive genes, and fortify stress tolerance mechanisms in plants. This review presents a comprehensive analysis of Se uptake pathways, its speciation, and incorporation into plant metabolic systems, as well as the diverse physiological and biochemical roles of Se and/or SeNPs in regulating plant defense mechanisms. A key focus is placed on SeNPs as a powerful tool for nano-enabled stress alleviation and biofortification in crop plants in modern agriculture. We further highlight how integrated multi-omics approaches are decoding the complex molecular networks underlying Se-mediated tolerance. However, the narrow optimal concentration window between benefit and phytotoxicity demands precise application. By bridging fundamental mechanisms with emerging nano-biotechnological applications, this review establishes the importance of Se and SeNPs as promising and sustainable, eco-friendly agents for developing climate-resilient crops, directly contributing to future food security.

Drought is one of the most detrimental abiotic stresses, severely constraining crop productivity on a global scale. Prolonged water deficits associated with climate change impair plant growth and contribute to substantial agricultural yield losses each year. In this study, we investigated the roles of nitric oxide (NO) and hydrogen sulfide (H₂S) in mediating stress tolerance in common bean, integrating physiological, biochemical, and molecular analyses to elucidate their regulatory functions under simulated water-deficit conditions. PEG-induced osmotic stress significantly reduced plant growth, which was associated with impaired nutrient uptake, enhanced oxidative stress, decreased PSII efficiency, and reduced photosynthetic performance. However, PEG-induced osmotic stress also stimulated the antioxidant defense system, increased proline accumulation, and elevated endogenous NO and H₂S levels, contributing to a partial mitigation of oxidative damage (O₂•^-, H₂O₂, and TBARS). Furthermore, PEG-induced osmotic stress upregulated the expression of antioxidant-related genes while downregulating photosynthesis-related genes. Exogenous application of sodium hydrosulfide (200 μM NaHS; H₂S donor) and sodium nitroprusside (100 μM SNP; NO donor) effectively alleviated stress-induced damage by maintaining photosynthetic capacity through enhanced expression of PSII-associated genes, improved stomatal regulation, and preservation of chloroplast ultrastructure. In addition, NaHS and SNP treatments promoted endogenous NO and H₂S production and reduced oxidative damage by activating antioxidant defense mechanisms. Notably, the combined application of SNP and NaHS produced the strongest protective effect under PEG-induced osmotic stress conditions. Pharmacological approaches using the NO scavenger cPTIO and the H₂S scavenger hypotaurine revealed that the protective effects of both donors were significantly attenuated upon scavenging either signaling molecule, indicating a strong functional interdependence between NO and H₂S pathways. Overall, our findings demonstrate that NO and H₂S operate through a coordinated signaling network to regulate plant tolerance under PEG-induced osmotic stress, providing a potential strategy for improving stress resilience in legume crops.