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.

Date palm (Phoenix dactylifera L.) is an important crop in arid regions and it is well adapted to desert ecosystems. To understand its remarkable ability to grow and yield in water-limited environments, we conducted experiments in which water was withheld for up to 4 weeks. In response to drought, root, rather than leaf, osmotic strength increased, with organic solutes such as sugars and amino acids contributing more to the osmolyte increase than minerals. Consistently, carbon and amino acid metabolism was acclimated toward biosynthesis at both the transcriptional and translational levels. In leaves, a remodeling of membrane systems was observed, suggesting changes in thylakoid lipid composition which, together with the restructuring of the photosynthetic apparatus, indicated an acclimation preventing oxidative damage. Thus, xerophilic date palm avoids oxidative damage under drought by combined prevention and rapid detoxification of oxygen radicals. Although minerals were expected to serve as cheap key osmotics, date palm also relies on organic osmolytes for osmotic adjustment in the roots during early drought acclimation. The diversion of these resources away from growth is consistent with the date palm strategy of generally slow growth in harsh environments and clearly indicates a trade-off between growth and stress-related physiological responses. Osmotic strength of date palm roots increases with soil desiccation, for which the accumulation of organic osmolytes, such as sugars and amino acids, is essential to complement energetically cheap mineral osmotics.

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.

Maize is highly susceptible to drought, which affects growth and yield. This study investigated how bacterial volatile organic compounds (BVOCs) affect maize drought tolerance. Drought reduced shoot size but increased root length, an adaptation for accessing deeper soil moisture. BVOCs from strain D12 significantly increased root length and shoot growth under drought conditions. Drought also altered root biochemistry, decreasing enzyme activity, and increased osmolyte levels. BVOCs from strains F11 and FS4-14 further increased osmolyte levels but did not protect membranes from oxidative damage, while BVOCs from strains D12 and D7 strains reduced osmolyte levels and cell damage. In shoots, drought increased the levels of osmolytes and oxidative stress markers. BVOCs from FS4-14 had minimal effects on shoot biochemistry. BVOCs from D12 and F11 partially restored metabolic activity but did not reduce cell damage. BVOCs from D7 reduced metabolic activity and cell damage. These results suggest that BVOCs can modulate the biochemical response of maize to drought, with some strains evidencing the potential to enhance drought tolerance.

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.

The global agricultural productivity has been significantly impaired due to the extensive use of heavy metal. Cadmium (Cd) is now recognized as a significant soil and environmental contaminant that is primarily spread by human activity. This study investigates the possible impact of melatonin (ME) in mitigating the toxicity caused by Cd in pepper (Capsicum annuum L.) seedlings. There were three groups of plants used in the experiment: control (CK) plants, Cd-stressed plants and ME-pretreated + Cd-stressed plants. The concentration of ME and Cd was 1 mu M and 0.1 mM, respectively, and applied as root application. The results described that Cd treatment remarkably reduced growth parameters, impaired pigment concentration, hindered gas exchange traits. In contrast, ME supplementation significantly recovered these parameters by increase in growth and biomass production of pepper seedlings under Cd toxicity. In addition, ME application considerably increased osmolyte production and protein level in pepper leaves and roots. Furthermore, ME positively upregulated the antioxidant enzymes activity and effectively decreased the oxidative damage in pepper leaves and roots. The enhanced antioxidant enzymes activity performed a significant role in the reduction of H2O2 and MDA concentration in plants under Cd stress. The findings indicated that the application of ME to plants effectively alleviates the stress caused by Cd exposure. Moreover, ME demonstrates significant efficacy in mitigating the adverse impacts of Cd on pepper plants.

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.