Salt accumulation can degrade soil properties, decrease its productivity, and harm its ecological functions. Introducing salt-tolerant plant species associated with arbuscular mycorrhizal fungi (AMF) can act as an effective biological method for restoring salinized soils. AMF colonize plant roots and improve their nutrient acquisition capacity. However, there is limited knowledge on how AMF affects the production of signaling molecules, e.g., abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA), related to plant-microbe interactions under salinity. Here, we assess the potential benefits of the AMF Rhizophagus intraradices in enhancing plant growth and nutrient uptake in addition to modulating stress hormone signaling levels (ABA, SA, and JA) of the facultative halophyte Sulla carnosa under saline conditions. Plants were grown in pots filled with soil and irrigated with 200 mM NaCl for 1 month. AMF symbiosis substantially increased the shoot dry weight (+107%), root dry weight (+67%), photosynthetic pigment content (chlorophyll a, chlorophyll b, and carotenoids), and nutrient uptake (C, N, P, K, Cu, and Zn) while significantly limiting the increase in the shoot Na+ concentration and H2O2 content caused by salinity stress. Mycorrhizal symbiosis significantly enhanced the root and shoot SA levels by 450% and 32%, respectively, compared to the stressed non-inoculated plants, potentially contributing to enhanced systemic resistance and osmotic adjustment under saline conditions. Salt stress increased the shoot ABA content, especially in R. intraradices-inoculated plants (113% higher than in stressed non-mycorrhizal plants). These findings confirm that AMF mitigated the adverse effects of salinity on S. carnosa by increasing the SA and ABA levels and reducing oxidative damage.

Water scarcity has affected much of Chile for the past 15 years, and Amelichloa caudata, a native species adapted to arid conditions, may offer a solution. The hypothesis of this study is that both acetylsalicylic acid (ASA) and biosolids (BSs) can positively influence plant growth under water stress. This study assessed the effects of ASA and BSs on edaphic, physiological, biochemical, and productive parameters of A. caudata under water scarcity conditions. Results showed that both treatments enhanced biomass production, plant height, leaf number, and canopy weight. ASA improved water retention, mitigating water stress effects and leading to biomass levels comparable to controls. In contrast, BSs did not show significant benefits and had the lowest biomass values under all conditions. The highest root dry weight was observed in water-restricted plants, while ASA-treated plants had lower malondialdehyde (MDA) levels, indicating reduced oxidative stress. However, BS treatment increased MDA levels, suggesting more severe oxidative damage. Despite improvements in water retention, high salt concentrations in BSs may limit their effectiveness and further research is required to optimize application rates.

Arsenic (As) is a toxic metal that can harm plants by causing oxidative stress, stunting growth, and disrupting metabolism. This study investigates the potential effect of gamma-aminobutyric acid (GABA) and salicylic acid (SA) in mitigating the toxic effects of As on sunflower plants. The aim is to enhance growth, improve metabolite accumulation, strengthen antioxidant defenses, reduce oxidative stress, enhance nutrient status, and minimize As uptake in sunflower plants. To investigate the effect of GABA and SA on arsenic toxicity, two sunflower genotypes (FH-779 and FH-773) were exposed to arsenic at a concentration of 60 mg kg(-)(1) in the soil. The experimental design followed a completely randomized design with three replications of each treatment arranged in a factorial manner. The sunflower plants were treated with foliar sprays of GABA (200 mg L--(1)), SA (100 mg L--(1)), and a combination of both GABA + SA (200 + 100 mg L--(1)). Both FH-779 and FH-773 genotypes exhibited significant accumulation of As + 5 and As+ 3 in roots and leaves, resulting in reduced nutrient uptake. GABA, SA, and GABA + SA treatments alleviated As-induced oxidative stress by reducing hydrogen peroxide (H2O2) production and malondialdehyde (MDA) levels in both genotypes. These treatments also enhanced osmolyte accumulation, improving osmotic adjustment under As stress. Additionally, GABA and SA spray enhanced the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), aiding in scavenging reactive oxygen species (ROS) and preventing oxidative damage. The combination of GABA and SA had a more pronounced effect on the translocation and remediation of As compared to GABA and SA alone. Arsenic removal efficiency reached maximum in the GABA + SA treatment in both FH-779 and FH-773 genotypes, greater than control group, respectively. The findings of this study highlight the beneficial roles of gamma-aminobutyric acid and salicylic acid in mitigating the negative effects of arsenic on growth of sunflower plants. These compounds regulate photosynthetic pigments, osmotic pressure, and antioxidant defense systems, improve nutrient status, and reduce arsenic uptake. Salicylic acid and gamma-aminobutyric acid show potential for alleviating stress in other crops facing abiotic stress. This study highlights the impact of these compounds on plant defense mechanisms in stress conditions, providing a promising approach to reduce arsenic toxicity in crops, thereby improving agricultural productivity in contaminated environments.

Soil salinity is a major abiotic stress causing severe damage to plants. Thus, proper management approaches need to be developed to lessen the detrimental effect of salinity on crop growth and productivity. The objective of this study was to investigate the potential role of exogenous salicylic acid (SA) and potassium (K+) in mitigating the adverse effects of salt stress on tomato. Salt-stressed tomato seedlings Solanum lycopersicum L. cv. Agata were exposed to 0.1 mM SA and 5 mM K+, applied individually or simultaneously for two weeks. Obtained results showed that salt stress resulted in reduced growth rate associated with accumulation of Na+ ions, reduced K+ levels, lower K+/Na+ ratio, increased oxidative damage, reduced total chlorophyll and carbohydrate contents as well as disturbed proline accumulation and disrupted antioxidant system. Nevertheless, after SA and K+ supplementation, total chlorophyll, K+, total proteins, total carbohydrates, and proline contents as well as K+/Na+ ratio were significantly increased. Additionally, exogenous SA and K+ treatments enhanced the non-enzymatic and enzymatic antioxidant system and ensured better oxidative stress tolerance, as indicated by reduced H2O2 production and membrane lipid peroxidation, resulting in an increased membrane stability index. These effects were further enhanced by the simultaneous application of SA and K+, resulting in a better growth of salt-stressed tomato seedlings compared to single applications of these two growth regulators. Taken together, the results of the current study provide evidence that SA and K+ may interact to counteract the adverse effects of salt stress on the growth of tomato seedlings by improving osmotic and ionic homeostasis and upregulating the antioxidant defense system. Therefore, the simultaneous application of SA and K+ may be suggested as a promising approach for beneficial tomato growth at the seedling stage under salt-affected soil conditions.

Introduction Salt stress has emerged as a predominant abiotic factor that jeopardizes global crop growth and yield. The plant hormone salicylic acid (SA) has notable potential in mitigating salt toxicity, yet its mechanism in enhancing the salinity tolerance of tobacco plants is not well explored. Methods This study aimed to assess the potential benefits of exogenous SA application (1.0 mM) on tobacco seedlings subjected to saline soil conditions. Results The foliar spray of SA partially mitigated these salt-induced effects, as evidenced by a reduction of malondialdehyde content, and improvements of leaf K+/Na+ ratios, pigment biosynthesis, and electron transport efficiency under NaCl stress. Additionally, SA increased the contents of total phenolic compound and soluble protein by 16.2% and 28.7% to alleviate NaCl-induced oxidative damage. Under salt stressed conditions, the activities of antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, catalase, and peroxidase increased by 4.2%similar to 14.4% in SA sprayed tobacco seedlings. Exogenous SA also increased ascorbate and glutathione levels and reduced their reduced forms by increasing the activities of glutathione reductase, ascorbate peroxidase, monodehydroascorbate reductase and dehydroascorbate reductase. qRT-PCR analysis revealed that the key genes regulating SA biosynthesis, carbon assimilation, the antioxidant system and the ascorbate-glutathione cycle were activated by SA under conditions of salt stress. Discussion Our study elucidates the physiological and molecular mechanisms of exogenous SA in enhancing plant salt tolerance and provides a practical basis for crop improvement in saline environments.

Cadmium (Cd) toxicity negatively impacts plant health and productivity. Nanosilica (SiO2NPs) and salicylic acid (SA) enhance plant performance and alleviate heavy metals stress. Yet, their combined effects against Cd-toxicity in rice remained less-explored. Thus, a hydroponic study investigated the individual and combined effects of SiO2NPs and SA on Cd-stress mitigation in rice at physio-biochemical, cellular, and molecular levels. Results indicated that Cd-alone treatment caused a significant reduction in rice growth and biomass and photosynthetic efficiency, which was associated with oxidative damage caused by enhanced Cd-accumulation in plant tissues. Cd-induction also potentiated its phytotoxicity by triggering enzymatic antioxidants against the extra production of reactive oxygen species (ROS). The addition of SiO2NPs and/or SA markedly minimized the Cd-induced toxicity by reducing Cd-bioaccumulation (42-56%), protecting photosynthetic efficiency, which were directly correlated with seedling biomass and restored cellular structures (leaf ultrastructure and surface morphology). The combined application of SiO2NPs and SA was more effective in activating antioxidant enzymes, phytohormones biosynthesis, and reducing oxidative damages caused by Cd than sole application. This was evident in the decreased production of ROS, malondialdehyde contents (29-37%), and recovered membrane stability. Moreover, SiO2NPs and/or SA relieved Cd-bioaccumulation (41-56%) by downregulating the Cd-related transporter genes (OsNramp1, OsNramp5, OsHMA2, and OsHMA3). Altogether, the cellular Cd-accumulation, photosynthesis, antioxidant defense, and phytohormones against oxidative stress can be ideal markers for cultivating rice in Cdcontaminated soils.

Lead is one of the major environmental pollutants which is highly toxic to plants and living beings. The current investigation thoroughly evaluated the synergistic effects of oxalic acid (OA) and salicylic acid (SA) on Zea mays L. plants subjected to varying durations (15, 30, 30, and 45 days) of lead (Pb) stress. Besides, the effects of oxalic acid (OA) combined with salicylic acid (SA) for different amino acids at various periods of Pb stress were also investigated on Zea mays L. The soil was treated with lead nitrate Pb (NO3)(2) (0.5 mM) to induce Pb stress while the stressed plants were further treated using oxalic acid (25 mg/L), salicylic acid (25 mg/L), and their combination OA + SA (25 mg/L each). Measurements of protein content, malondialdehyde (MDA) levels, guaiacol peroxidase (GPOX) activity, catalase (CAT) activity, GSH content, and Pb concentration in maize leaves were done during this study. MDA levels increased by 71% under Pb stress, while protein content decreased by 56%, GSH content by 35%, and CAT activity by 46%. After treatment with SA, OA, and OA+SA, there was a significant reversal of these damages, with the OA+SA combination showing the highest improvement. Specifically, OA+SA treatment led to a 45% increase in protein content and a 39% reduction in MDA levels compared to Pb treatment alone. Moreover, amino acid concentrations increased by 68% under the Pb+OA+SA treatment, reflecting the most significant recovery (p < 0.0001).

Salicylic acid (SA) is a vital phytohormone that can mitigate the detrimental effects caused by abiotic stress in plants; however, these effects vary with SA concentrations, plant species and stress types. Although sunflowers can be cultivated on saline-alkali soil, they remain susceptible to salt stress, especially at the seedling stage. Therefore, we aimed to explore the role of SA in improving salt stress tolerance in sunflowers. Here, we conducted physiology and transcriptomic analyses to assess the effects of four SA concentrations applied through foliar spraying on sunflower seedlings under salt stress. Initially, the height and stem diameter were impeded, and the chlorophyll fluorescence parameters (such as Fv/Fm, Fv/Fo, and PIabs) decreased, but the antioxidant enzyme activity and malondialdehyde and glutathione contents increased when the seedlings exposed to salt stress (250 mM NaCl); meanwhile, the levels of most physiological indices (including plant growth, chlorophyll fluorescence, and reactive oxygen species) significantly recovered after spraying four concentrations of SA solution. Furthermore, the differentially expressed genes identified from transcriptome analysis were mainly involved in photosynthesis, plant hormone signaling, MAPK pathway, and secondary metabolite biosynthesis, which may contribute to the SA-induced response under salt stress. The key genes and TFs crucially involved in the response to salt stress and mitigating its detrimental effects were identified through K-means clustering and WGCNA. We may infer that SA can activate the self-regulatory system, thereby mitigating oxidative damage and enhancing photosynthesis and salt tolerance in plants. Overall, our results demonstrate that 1.0 mM SA is the most effective concentration for alleviating salt stress in sunflowers. This study provides initial insights into the ability of SA to alleviate salt stress and its underlying molecular mechanisms, which is valuable for both field management practices and understanding sunflower tolerance to salinity.

Chromium is a widespread toxic trace metal in cultivated lands owing to human actions, insufficient treatment, and unregulated disposal. Chromium toxicity is facilitated by the production of reactive oxygen species, which induce lipid peroxidation and damage the cellular membranes and nuclei. This study evaluated the preparation and characterization of Pterospermum-derived biochar based on a set of test categories from the International Biochar Initiative. The aim of this study was to assess the effectiveness of Pterospermum-derived biochar and salicylic acid (SA) in promoting the growth and biochemical attributes of tomato plants grown in Crcontaminated soils. The results showed that Cr toxicity reduced root (42.86 %) and shoot (23.26 %) lengths, which subsequently increased (65 % root and 39.94 % shoot lengths) under SA and biochar treatments. Increased levels of superoxide anions (O2 center dot-) (104.43 %), malondialdehyde (MDA) (115.53 %), and H2O2 (72.35 %) were observed in the Cr-treated tomato plantlets. The combined treatment of SA and biochar effectively reduced MDA, H2O2, and O2 center dot- levels by 51.17%, 36.89%, and 45.53%, respectively, under Cr toxicity conditions. In addition, the combined treatment with SA and biochar enhanced the activity and gene expression of dehydrogenase (7.06fold), guaiacol peroxidase (6.51-fold), superoxide dismutase (7.90-fold), polyphenol oxidase (1.89-fold), glutathione-s-transferase (2.55-fold), ascorbate peroxidase (1.26-fold), and glutathione peroxidase (8.75-fold) under Cr toxicity conditions. The results highlight the combined treatment of biochar and SA as an effective amendment that offers an environment-friendly method for alleviating Cr toxicity and promoting growth and the antioxidative defense system in tomato plantlets.

Drastic change in global climatic conditions has signi ficantly increased the frequency of abiotic stresses, such as different temperature regimes (high, low, or freezing stress), uneven precipitation leading to flooding or drought, soil salinization, cyclones and hurricanes which pose a major challenge to the crop productivity and food security. Therefore, it becomes imperative for the global science community to engineer stress tolerance in crop plants to ensure enough food for the globe. Plant growth regulators play an important function in stress management. One putative plant hormone that aids plants in coping with biotic and abiotic stressors is salicylic acid (SA). SA also cooperates with other phytohormones, such as gibberellins, auxins, abscisic acid, jasmonic acid, ethylene, polyamines, nitric oxide, and to counter the negative effects of environmental perturbations. Moreover, SA shields plants from oxidative stress by reducing the production of reactive oxygen species in challenging circumstances. Additionally, SA stimulates gas exchange, photosynthesis, and osmolyte synthesis in plants, which counteract the damage caused by ROS. Exogenous application of SA to agricultural crops including medicinal and aromatic plants improves their abiotic stress tolerance, either individually or in combination with other phytohormones. SA can stimulate the production of secondary metabolites by controlling the expression of stress -related genes, activating or regulating several key enzymes, and balancing the ion content. The present review summarizes the various mechanisms by which SA confers abiotic stress tolerance in plants through homeostasis, signalling, and crosstalk with other phytohormones. (c) 2024 SAAB. Published by Elsevier B.V. All rights reserved.