To feed the nearly 10 billion people by the year 2050, agricultural activities and yield must be enhanced substantially, maintaining soil health and overpowering the expected adverse effects of climate change. High soil salinity is one of the major concerns in future farming, as salinity is a prominent abiotic stress that significantly impacts plants inhabiting arid and semiarid environments worldwide. The increasing levels of soil salinity are proving detrimental to agriculture, the general productivity of the ecosystem, and the economy at large. Excessive salt accumulation in plants leads to an osmotic imbalance, resulting in a decrease in photosynthesis, formation of reactive oxygen species, DNA damage, hormonal instability, and decreased water and mineral uptake. To mitigate the adverse impacts of salt stress, along with diverse physiological mechanisms, plants have developed symbiotic associations with endophytic microorganisms that reside within the plant tissues and help the plants in many ways. Endophytes have been found to alleviate the effects of salinity stress by diverse mechanisms-synthesis of osmolytes, and antioxidant enzymes such as catalase, superoxide dismutase, and peroxidase; synthesis and modulation of phytohormones such as ethylene, indole-3-acetic acid, gibberellin, abscisic acid, etc.; promotion of siderophore production and exopolysaccharide formation; carrying out nitrogen fixation, and increasing phosphate solubilization. In this review, the effects of salinity stress on plants, and the mechanisms by which endophytic microorganisms help the plants to withstand such stress are discussed at length. The application of tailored endophytic microbial consortia holds the key to future food security through sustainable agriculture.

Plant growth regulators (PGRs) improve crop growth and mitigate the adverse effects of drought stress. This study explores the effects of various PGRs including melatonin (MT), indole-butyric acid (IBA) and gibberellic acid (GA3) on drought-tolerant Zhongzhe 9 (ZZ9) and Xintaitang 22 (ROC22), as well as drought-sensitive varieties Guitang-44 (GT44) and Funong 41 (FN41) varieties. A pot experiment was conducted to evaluate the foliar application of these hormones alone or in combination on sugarcane seedlings under drought stress conditions. At the sixth leaf stage, drought stress was induced by reducing soil moisture to 40%-45% field capacity. Results showed that the drought-sensitive variety GT44 had the highest plant height (17.97 cm), while PGRs application enhanced the relative water content (RWC) in FN41 by 0.96%. PGRs treatment also increased plant height by 33.98% and RWC by 3.26% compared to controls. MT application significantly increased chlorophyll a and b contents in FN41 by 4.82% and 4.51%, respectively. Antioxidant enzyme activities superoxide dismutase and peroxidase increased by 16.39% and 12.57%, respectively, indicating enhanced oxidative stress defence. Moreover, PGRs applications reduced hydrogen peroxide and malondialdehyde (MDA) accumulation, signifying decreased oxidative damages. The combinations of MT + GA3 and MT + IBA + GA3 significantly improved the plant growth attributes, antioxidant enzymes, osmolytes and reduced the accumulation of ROS and MDA content in both tolerant and sensitive varieties under drought stress. Thus, combined application of MT + GA3 and MT + IBA + GA3 treatments effectively mitigated drought stress in sugarcane seedlings, providing valuable insights for sustainable agricultural practices.

Salinity stress has become a major threat to worldwide crop production. Exogenous melatonin (MT) has appeared as a promising treatment against salt stress in several plant species. However, MT effect on the tolerance of sorghum plants under different saline conditions (moderate and severe) remains ambiguous. This study was carried out to explore the impact of MT (0, 50, 100 and 200 mu M) as a foliar application on sorghum seedlings grown under moderate and severe saline conditions using sodium chloride, NaCl (75 and 150 mu M NaCl). Salinity treatments were applied as solution in sand medium in pots. The results demonstrated that rising salinity level negatively affected plant growth, photosynthetic pigments (chlorophylls and carotenoids), leaf water status and ionic homeostasis (sodium, potassium, and calcium ions). Applied-MT specifically at 100 or 200 mu M enhanced the osmotic balance, cell membrane stabilizing and leaf relative water content. These effects were associated with an obvious restriction to the level of hydrogen peroxide, lipid peroxidation (malondialdehyde content) and methylglyoxal. Moreover, antioxidant activities of peroxidase, catalase, superoxide dismutase, and ascorbate peroxidase enzymes were modulated by MT treatments. Molecular docking modeling assessment illustrated top-ranked confirmations between MT and the target antioxidant enzymes. MT forms multiple hydrogen bonds with key amino acid residues for glycine (A: 162), tryptophan (A: 41), leucine (A: 165), tyrosine (A: 235) in the active site of ascorbate peroxidase. The alkyl interactions with leucine (A: 37), arginine (A: 38) and cysteine (A: 168) also contribute to its high affinity. Despite sorghum plant is commonly moderately tolerant to salinity stress, the results of this study confirmed its high sensitivity to a wide range of saline conditions at early growth stages. Melatonin spraying led to improvements in various morphological, physiological and biochemical mechanisms that harmonized together to confer stress resistance to salt-stressed sorghum seedlings.

Arbuscular mycorrhizal fungi (AMF) are increasingly recognized for their beneficial impacts on plants facing various environmental stresses, playing a pivotal role in enhancing ion uptake, water retention, and overall plant productivity. Similarly, plant growth-promoting rhizobacteria (PGPR) contribute to plant growth by facilitating nitrogen assimilation and producing growth regulators. While the individual applications of AMF and PGPR are well-documented, there is limited research on their combined effects, particularly in heavy metal stress physiology. Therefore, the synergistic effects of AMF and PGPR in metal-stressed conditions, a relatively un-explored area in plant stress physiology. A hydroponic experiment was conducted under the combined effects of PGPR i.e., Bacillus cereus Pb25 and AMF i.e., Glomus intraradices under the hydroponic solution spiked with copper (Cu) stress i.e., 100 mu M on biochemical, morphological and physiological characteristics of maize (Zea mays L.) seedlings. Our results showed that the Cu toxicity in the nutrient solution showed a significant declined in the growth, gas exchange attributes and nutrient uptake in Z. mays. However, Cu toxicity significantly increased oxidative stress biomarkers, organic acids, enzymatic and non-enzymatic antioxidants including their gene expression in Z. mays seedlings. Although, the application of PGPR and AMF showed a significant increase in the plant growth and biomass, gas exchange characteristics, nutrient uptake, enzymatic and non-enzymatic compounds and their gene expression and also decreased the oxidative stress and Cu uptake in different parts of the plant. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Background: Arsenic (As) is a highly toxic and carcinogenic pollutant commonly found in soil and water, posing significant risks to human health and plant growth. Objective: The objectives of this study to evaluate morphological, biochemical, and physiological markers, as well as ion homeostasis, to alleviate the toxic effects of As in sunflowers through the exogenous application of salicylic acid (SA), gamma-aminobutyric acid (GABA), and their combination. Methods: A pot experiment was conducted using two sunflower genotypes, FH-779 and FH-773, subjected to As stress (60 mg kg(-1)) to evaluate the effects of SA at 100 mg L-1, GABA at 200 mg L-1, and their combination on growth and related physiological and biochemical attributes under As stress. Results: The study revealed that As toxicity had a detrimental effect on various growth parameters, chlorophyll pigments, relative water content, total proteins, and nutrient uptake in sunflower plants. It also led to increased oxidative stress, as indicated by higher levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2), along with As accumulation in the roots and leaves. However, the application of SA and GABA protected against As-induced damage by enhancing the enzymatic antioxidant defense system. This was achieved through the activation of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities, as well as an increase in osmolytes. They also improved nutrient acquisition and plant growth under As toxicity. Conclusions: We investigated the regulatory roles of SA and GABA in mitigating arsenic-induced phytotoxic effects on sunflower. Our results revealed a significant interaction between SA and GABA in regulating growth, photosynthesis, metabolites, antioxidant defense systems, and nutrient uptake in sunflower under As stress. These findings provide valuable insights into plant defense mechanisms and strategies to enhance stress tolerance in contaminated environments. In the future, SA and GABA could be valuable tools for managing stress in other important crops facing abiotic stress conditions.

Purpose Fly ash (FA) is a waste byproduct produced in large quantities by coal-fired power stations. Its accumulation causes environmental issues, so it needs safe disposal of FA to reduce its accumulation. Herbal medicines like Mentha arvensis are being investigated worldwide for the prevention and treatment of a wide range of disorders because of their remarkable therapeutic benefits and absence of side effects when compared to current medications. Methods The aim of the study was to determine the effect of different concentrations of fly ash on growth, biochemical parameters, and constituents of essential oils of M. arvensis. Results The findings demonstrated that FA improved some important physical and chemical properties of soil. The use of FA-amended soil (10%) significantly improved the growth performance, photosynthetic pigments, protein, proline, antioxidant activity, and mineral contents. Conversely, the higher fly ash doses (25%) resulted in oxidative stress by increasing lipid peroxidation and electrolytic leakage levels, which negatively affected all of the aforementioned parameters. A confocal microscopic examination of the roots of M. arvensis revealed that fly ash at concentration of 25% resulted in membrane damage. In addition, alcohols, phenols, allenes, ketenes, isocynates, and hydrocarbons were among the functional groups found in the control and 10% of fly ash. Gas chromatography-mass spectrometry analysis of essential oils of M. arvensis treated with 10% fly ash revealed the presence of 32 bioactive components. Conclusions It is possible to use the 10% FA concentrations to increase plant growth and decrease the accumulation of FA that pollutes the environment.

Soil pollution with heavy metals has grown to be a big hassle, leading to the loss in farming production particularly in developing countries like Pakistan, where no proper channel is present for irrigation and extraction of these toxic heavy metals. The present study aims to ameliorate the damages caused by heavy metal ions (Hg-Mercury) on rapeseed (Brassica napus L.) via a growth regulator (alpha-tocopherol 150 mg/L) and thermopriming technique at 4 degrees C and 50 degrees C to maintain plant agronomical and physiological characteristics. In pot experiments, we designed total of 11 treatments viz.( T0 (control), T1 (Hg4ppm), T2 (Hg8ppm), T3 (Hg4ppm + 4 degrees C), T4 (Hg4ppm + 4 degrees C + tocopherol (150 m/L)), T5 (Hg4ppm + 50 degrees C), T6 (Hg4ppm + 50 degrees C + tocopherol (150 mg/L)), T7 (Hg8ppm + 4 degrees C), T8 (Hg8ppm + 4 degrees C + tocopherol (150 mg/L)), T9 (Hg8ppm + 50 degrees C), T10 (Hg8ppm + 50 degrees C + tocopherol (150 mg/L) the results revealed that chlorophyll content at p 0.05) 50 degrees C thermopriming under 8 ppm high mercuric chloride stress (T9 = Hg8ppm + 50 degrees C) representing the tolerance of selected specie by synthesizing osmolytes to resist oxidation mechanism. Furthermore, reduction in % MC (moisture content) is easily improved with foliar application of alpha-tocopherol and 50 degrees C thermopriming and 4 ppm heavy metal stress at T6 = Hg4ppm + 50 degrees C + alpha-tocopherol (150 mg/L), with a remarkable increase in plant vigor and germination energy. It has resulted that the inhibitory effect of only lower concentration (4 ppm) of heavy metal stress was ameliorated by exogenous application of alpha-tocopherol and thermopriming technique by synthesizing high levels of proline and antioxidant activities in maintaining seedling growth and development on heavy metal contaminated soil.

Priming enables plants to respond more promptly, minimise damage, and survive subsequent stress events. Here, we aimed to assess the efficacy of priming and cross-priming in mitigating the stress caused by waterlogging and/or dehydration in soybeans (Glycine max). Soybean plants were cultivated in a greenhouse in plastic pots in which soil moisture was maintained at pot capacity through irrigation. The first stress was applied in plants at the vegetative stage for 5 days and involved either dehydration or waterlogging, depending on the treatment. Subsequently, the plants were irrigated or drained and maintained at pot capacity until the second stress. For the second stress, the conditions were repeated in plants at the reproductive stage. We then evaluated the levels of hydrogen peroxide (H2O2), lipid peroxidation, total soluble sugars (TSS), amino acids, proline, and starch, and the activity of antioxidant, fermentative, and aminotransferase enzymes. Under waterlogging and dehydration, priming and cross-priming significantly increased the activity of antioxidant enzymes and the levels of TSS, amino acids, and proline while reducing H2O2 concentration and lipid peroxidation. Under waterlogging, priming suppressed fermentative activity and increased carbohydrate content. This demonstrates that soybean plants activate their defence systems more promptly when subjected to priming.