Role of Signaling Molecules Sodium Nitroprusside and Arginine in Alleviating Salt-Induced Oxidative Stress in Wheat

Enriched biochars with silicon and calcium nanoparticles mitigated salt toxicity and improved safflower plant performance

Modifying biochar with nano-nutrients is one of the most effective methods in improving the efficiency of biochar in reducing the adverse effects of environmental stresses such as salinity on plant growth and productivity. The possible effects of solid biochar, nano-silicon dioxide enriched biochar, nano-calcium carbonate enriched biochar, and combined application of these enriched biochars on physiological performance of safflower (Carthamus tinctorius L.) were evaluated under different levels of salt stress (non-saline, 6 and 12 dSm-1). Salt stress increased sodium content, reactive oxygen species generation, and antioxidant enzymes activity, but decreased potassium, calcium, magnesium, iron, zinc, silicon, photosynthetic pigments, leaf water content, and seed yield (by about 36%) of safflower plants. The addition of biochar forms to the saline soil improved growth (up to 24.6%) and seed yield (up to 37%) of safflower by reducing sodium accumulation (by about 32%) and ROS generation and enhancing nutrient uptake, photosynthetic pigments, and water contents of leaves. The combined forms of enriched biochars were the best treatment on reducing salt stress effects on safflower plants. Therefore, application of enriched biochars has a high potential to reduce the harmful effects of salt stress on plants.

Integrative analysis of the transcriptome and metabolome reveals Bacillus atrophaeus WZYH01-mediated salt stress mechanism in maize (Zea mays L.)

Maize is an important food crop that is affected by salt stress during growth, which can hinder plant growth and result in a significant decrease in yield. The application of plant growth-promoting rhizobacteria can improve this situation to a certain extent. However, the gene network of rhizosphere-promoting bacteria regulating the response of maize to salt stress remains elusive. Here, we used metabolomics and transcriptomics techniques to elucidate potential gene networks and salt-response pathways in maize. Phenotypic analysis showed that the Bacillus atrophaeus treatment improved the plant height, leaf area, biomass, ion, nutrient and stomatal indicators of maize. Metabolomic analysis identified that differentially expressed metabolites (DEMs) were primarily concentrated in the arginine, proline and phytohormone signaling metabolic pathways. 4-Hydroxyphenylacetylglutamic acid, L-histidinol, oxoglutaric acid, L-glutamic acid, L-arginine, and L-tyrosine were significantly increased in the Bacillus atrophaeus treatment. Weighted gene coexpression network analysis (WGCNA) identified several hub genes associated with salt response: Zm00001eb155540 and Zm00001eb088790 (ABC transporter family), Zm00001eb419060 (extra-large GTP-binding protein family), Zm00001eb317200 (calcium-transporting ATPase), Zm00001eb384800 (aquaporin NIP1-4) and Zm00001eb339170 (cytochrome P450). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that genes related to plant hormone signal transduction and the MAPK signaling pathway were involved in the response to the effect of Bacillus atrophaeus under salt stress. In the plant hormone signal transduction pathway, 3 differentially expressed genes (DEGs) encoding EIN3/EILs protein, 3 DEGs encoding GH3, 1 DEG encoding PYR/PYL and 6 DEGs encoding PP2C were all upregulated in Bacillus atrophaeus treatment. In the MAPK signaling pathway, 2 DEGs encoding CAT1 and 2 DEGs encoding WRKY22/WRKY29 were significantly upregulated, and the expression of DEGs encoding RbohD was downregulated by the application of Bacillus atrophaeus. In conclusion, the application of Bacillus atrophaeus under salt stress regulated key physiological and molecular processes in plants, which could stimulate the expression of genes related to ion transport and nutrients in maize, alleviate salt stress and promote maize growth to some extent, deepening our understanding of the application of Bacillus atrophaeus under salt stress to improve the salt-response gene network of maize growth.

Selenium Improves the Control Efficacy of Phytophthora nicotianae by Damaging the Cell Membrane System and Promoting Plant Energy Metabolism

Tobacco black shank (TBS), caused by Phytophthora nicotianae, poses a significant threat to tobacco plants. Selenium (Se), recognized as a beneficial trace element for plant growth, exhibited inhibitory effects on P. nicotianae proliferation, disrupting the cell membrane integrity. This action reduced the energy supply and hindered hyphal transport through membrane proteins, ultimately inducing hyphal apoptosis. Application of 8 mg/L Se through leaf spraying resulted in a notable decrease in TBS incidence. Moreover, Se treatment preserved chloroplast structure, elevated chitinase activities, β-1,3-GA, polyphenol oxidase, phenylalanine ammonia-lyase, and increased hormonal content. Furthermore, Se enhanced flavonoid and sugar alcohol metabolite levels while diminishing amino acid and organic acid content. This shift promoted amino acid degradation and flavonoid synthesis. These findings underscore the potential efficacy of Se in safeguarding tobacco and potentially other plants against P. nicotianae.

Heat and Wheat: Adaptation strategies with respect to heat shock proteins and antioxidant potential; an era of climate change

Extreme changes in weather including heat-wave and high-temperature fluctuations are predicted to increase in intensity and duration due to climate change. Wheat being a major staple crop is under severe threat of heat stress especially during the grain-filling stage. Widespread food insecurity underscores the critical need to comprehend crop responses to forthcoming climatic shifts, pivotal for devising adaptive strategies ensuring sustainable crop productivity. This review addresses insights concerning antioxidant, physiological, molecular impacts, tolerance mechanisms, and nanotechnology-based strategies and how wheat copes with heat stress at the reproductive stage. In this study stress resilience strategies were documented for sustainable grain production under heat stress at reproductive stage. Additionally, the mechanisms of heat resilience including gene expression, nanomaterials that trigger transcription factors, (HSPs) during stress, and physiological and antioxidant traits were explored. The most reliable method to improve plant resilience to heat stress must include nano-biotechnology-based strategies, such as the adoption of nano-fertilizers in climate-smart practices and the use of advanced molecular approaches. Notably, the novel resistance genes through advanced molecular approach and nanomaterials exhibit promise for incorporation into wheat cultivars, conferring resilience against imminent adverse environmental conditions. This review will help scientific communities in thermo-tolerance wheat cultivars and new emerging strategies to mitigate the deleterious impact of heat stress.

Role of Acetic Acid and Nitric Oxide against Salinity and Lithium Stress in Canola (Brassica napus L.)

In this study, canola (Brassica napus L.) seedlings were treated with individual and combined salinity and lithium (Li) stress, with and without acetic acid (AA) or nitric acid (NO), to investigate their possible roles against these stresses. Salinity intensified Li-induced damage, and the principal component analysis revealed that this was primarily driven by increased oxidative stress, deregulation of sodium and potassium accumulation, and an imbalance in tissue water content. However, pretreatment with AA and NO prompted growth, re-established sodium and potassium homeostasis, and enhanced the defense system against oxidative and nitrosative damage by triggering the antioxidant capacity. Combined stress negatively impacted phenylalanine ammonia lyase activity, affecting flavonoids, carotenoids, and anthocyanin levels, which were then restored in canola plants primed with AA and NO. Additionally, AA and NO helped to maintain osmotic balance by increasing trehalose and proline levels and upregulating signaling molecules such as hydrogen sulfide, γ-aminobutyric acid, and salicylic acid. Both AA and NO improved Li detoxification by increasing phytochelatins and metallothioneins, and reducing glutathione contents. Comparatively, AA exerted more effective protection against the detrimental effects of combined stress than NO. Our findings offer novel perspectives on the impacts of combining salt and Li stress.

Regulatory effects of Hemin on prevention and rescue of salt stress in rapeseed (Brassica napus L.) seedlings

BACKGROUND

Salt stress severely restricts rapeseed growth and productivity. Hemin can effectively alleviate salt stress in plants. However, the regulatory effect of Hemin on rapeseed in salt stress is unclear. Here, we analyzed the response and remediation mechanism of Hemin application to rapeseed before and after 0.6% (m salt: m soil) NaCl stress. Experiment using two Brassica napus (AACC, 2n = 38) rapeseed varieties Huayouza 158R (moderately salt-tolerant) and Huayouza 62 (strongly salt-tolerant). To explore the best optional ways to improve salt stress resistance in rapeseed.

RESULTS

Our findings revealed that exogenous application of Hemin enhanced morph-physiological traits of rapeseed and significantly attenuate the inhibition of NaCl stress. Compared to Hemin (SH) treatment, Hemin (HS) significantly improved seedlings root length, seedlings height, stem diameter and accumulated more dry matter biomass under NaCl stress. Moreover, Hemin (HS) significantly improved photosynthetic efficiency, activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and decreased electrolyte leakage (EL) and malondialdehyde (MDA) content, thus resulting in the alleviation of oxidative membrane damage. Hemin (HS) showed better performance than Hemin (SH) under NaCl stress.

CONCLUSION

Hemin could effectively mitigate the adverse impacts of salt stress by regulating the morph-physiological, photosynthetic and antioxidants traits of rapeseed. This study may provide a basis for Hemin to regulate cultivated rapeseed salt tolerance and explore a better way to alleviate salt stress.

Water deficit stress changes in physiological, biochemical and antioxidant characteristics of anise (Pimpinella anisum L.)

This study was designed to evaluate the impact of water deficit stress on the seed yield and its components, physiological functions, fatty acid content and compositions, essential oil (EO) content and compositions, phenolic acids and flavonoids amounts, and antioxidant activities of anise seeds. Plants evaluations were performed under well-watered (WW), moderate water deficit stressed (MWDS), and severe water deficit stressed (SWDS). The results revealed that SWDS significantly reduced seed yield, branch number per plant, seed number, umbel number, and thousand seed weight. Water deficit stress also caused a decrease in chlorophyll content, relative water content, quantum efficiency of photosystem II, and cell membrane stability, while increasing leaf temperature. The analysis of fatty acid composition indicated that petroselinic acid was the main fatty acid and its percentage increased by 8.75% and 14.60% under MWDS and SWDS, respectively. Furthermore, MWDS increased the EO content by 1.48 times, while it decreased by 41.32% under SWDS. The chemotype of EO was altered from t-anethole/estragole in WW seeds to t-anethole/β-bisabolene in treated seeds. Higher levels of total phenolics were detected in stressed seeds. Water deficit stress increased the amount of the major class, naringin, by 1.40 and 1.26 times under MWDS and SWDS. The evaluation of antioxidant activity through reducing power, DPPH, and chelating ability assays indicated that stressed seeds exhibited the highest activity. The study's findings suggest that the application of drought stress before harvesting can regulate the production of bioactive compounds, which can affect the industrial and nutritional values of anise seeds.

Modulation of salt stress through application of citrate capped silver nanoparticles and indole acetic acid in maize

The present study was conducted to determine the effect of indole acetic acid (IAA) and Citrate Capped Silver Nanoparticles (Cit-AgNPs) on various attributes of maize under induced salinity stress. Seeds of the said variety were collected from Cereal Crop Research Institute (CCRI) Pirsabaq, Nowshera, sterilized and sown in earthen pots filled with 2 kg silt and soil (1:2) in triplicates in the green house of the Botany Department, University of Peshawar. Nanoparticles were analyzed by scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Thermo-gravimetric analysis (TGA) and Differential thermal analysis (DTA). Results of SEM revealed spherical morphology of Cit-AgNPs while EDX showed various elemental composition. TGA showed dominant weight loss up to 300 °C while the DTA showed major exothermic peaks at 420 °C. High Salinity concentration (80 mM) imposed significant detrimental impacts by reducing the agronomic attributes, photosynthetic pigments, osmolytes and antioxidant enzymes, which was remarkably ameliorated by the foliar application of Cit-AgNPs and IAA. Agronomic attributes including leaf, root and shoot fresh and dry weight was improved by 52-74%, 43-69% and 36-79% in individual as well as combined treatments of IAA and NPs. Photosynthetic pigments were amplified by 35-63%, total osmolytes were augmented by 39-68% and antioxidant enzymes including SOD and POD were boosted by 42-57% and 37-62% respectively, in combined as well as individual application. Conclusively, Cit-AgNPs are considered as salt mitigating entities that enhance the tolerance level of crop plants along with IAA, which may be beneficial for the plants growing in saline stressed environment.

Seed Treatment with Sodium Nitroprusside Ensures a Long-Term Physiological and Protective Effect on Wheat under Salinity

Although salinity inhibits plant growth, the use of a nitric oxide (NO) gasotransmitter can reduce its negative effects. In this study, the influence of 200 μM sodium nitroprusside (SNP) (donor of NO) on wheat plants (Triticum aestivum L., cv. Salavat Yulaev) in conditions of salinization (100 mM NaCl) was analyzed in pot experiments. Seed priming regulated the level of endogenous NO in normal and salinity conditions throughout the entire experiment (30 and 60 days). Salinity led to the strong accumulation of NO and H₂O₂, which is negative for plants, and significantly reduced leaf area and photosynthetic pigments (chlorophyll a and b and carotenoids). In addition, stress caused a drop in the content of reduced glutathione (GSH) and ascorbic acid (ASA), an accumulation of oxidized glutathione (GSSG), and significantly activated glutathione reductase (GR), ascorbate peroxidase (APX), and lipid peroxidation (LPO) in wheat leaves. SNP treatment significantly attenuated the negative effects of salinity on leaf area and photosynthetic pigments. An important indicator of reducing the damaging effect of salinity on treated plants is the stabilization of the content of GSH and ASA throughout the experiment (60 days). This condition has been associated with long-term modulation of GR and APX activity. Such an effect of 200 μM SNP may be related to its ability to reduce stress-induced accumulation of NO. Additional accumulation of proline also mitigated the negative effect of salinity on plants, and this also evidenced decreased LPO and H₂O₂ in them. For the first time, in natural growing conditions (small-scale field experiments), it was found that pre-sowing seed treatment with 200 μM SNP led to an improvement in the main yield indicators and an increase in the content of essential amino acids in wheat grains. Thus, SNP treatment can be used as an effective approach for prolonged protection of wheat plants under salinity and to improve grain yield and its quality.

Foliar Spraying of NaHS Alleviates Cucumber Salt Stress by Maintaining N+/K+ Balance and Activating Salt Tolerance Signaling Pathways

Hydrogen sulfide (H₂S) is involved in the regulation of plant salt stress as a potential signaling molecule. This work investigated the effect of H₂S on cucumber growth, photosynthesis, antioxidation, ion balance, and other salt tolerance pathways. The plant height, stem diameter, leaf area and photosynthesis of cucumber seedlings were significantly inhibited by 50 mmol·L^-1 NaCl. Moreover, NaCl treatment induced superoxide anion (O₂^·-) and Na⁺ accumulation and affected the absorption of other mineral ions. On the contrary, exogenous spraying of 200 μmol·L^-1 sodium hydrosulfide (NaHS) maintained the growth of cucumber seedlings, increased photosynthesis, enhanced the ascorbate-glutathione cycle (AsA-GSH), and promoted the absorption of mineral ions under salt stress. Meanwhile, NaHS upregulated SOS1, SOS2, SOS3, NHX1, and AKT1 genes to maintain Na⁺/K⁺ balance and increased the relative expression of MAPK3, MAPK4, MAPK6, and MAPK9 genes to enhance salt tolerance. These positive effects of H₂S could be reversed by 150 mmol·L^-1 propargylglycine (PAG, a specific inhibitor of H₂S biosynthesis). These results indicated that H₂S could mitigate salt damage in cucumber, mainly by improving photosynthesis, enhancing the AsA-GSH cycle, reducing the Na⁺/K⁺ ratio, and inducing the SOS pathway and MAPK pathway.

Nitric Oxide, a Key Modulator in the Alleviation of Environmental Stress-Mediated Damage in Crop Plants: A Meta-Analysis

Nitric oxide (NO) is a small, diatomic, gaseous, free radicle, lipophilic, diffusible, and highly reactive molecule with unique properties that make it a crucial signaling molecule with important physiological, biochemical, and molecular implications for plants under normal and stressful conditions. NO regulates plant growth and developmental processes, such as seed germination, root growth, shoot development, and flowering. It is also a signaling molecule in various plant growth processes, such as cell elongation, differentiation, and proliferation. NO also regulates the expression of genes encoding hormones and signaling molecules associated with plant development. Abiotic stresses induce NO production in plants, which can regulate various biological processes, such as stomatal closure, antioxidant defense, ion homeostasis, and the induction of stress-responsive genes. Moreover, NO can activate plant defense response mechanisms, such as the production of pathogenesis-related proteins, phytohormones, and metabolites against biotic and oxidative stressors. NO can also directly inhibit pathogen growth by damaging their DNA and proteins. Overall, NO exhibits diverse regulatory roles in plant growth, development, and defense responses through complex molecular mechanisms that still require further studies. Understanding NO's role in plant biology is essential for developing strategies for improved plant growth and stress tolerance in agriculture and environmental management.

Arbuscular Mycorrhizal Fungi and Compost-Based Biostimulants Enhance Fitness, Physiological Responses, Yield, and Quality Traits of Drought-Stressed Tomato Plants

Climate change-driven water resource constraints cause tomatoes to suffer from drought. The use of biostimulants has emerged as an important approach to enhancing resilience to drought. However, the roles of biostimulants in the physicochemical characteristics of tomatoes in response to drought are poorly understood. In this study, we evaluated the ability of arbuscular mycorrhizal fungi (AMF) and compost (versus NPK application) to improve the agro-physiology, yield, and fruit quality of tomato plants and their tolerance to drought by comparing them with conventional chemical fertilizers (NPK). Under drought conditions, plant growth traits associated with yield and fruit bioactive compounds (carotenoids: 73%; lycopene: 53%; polyphenols: 310%; and flavonoids: 158%) were increased in the AMF-tomato treatment. Compost significantly enhanced sugars (ca. 60%) and protein contents (ca. 20%). Moreover, AMF protected the photosynthetic apparatus from drought-induced oxidative stress, improved photosynthetic efficiency, leaf water potential, and osmolytes, and reduced malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) accumulation by increasing peroxidase (POX) (140%) and polyphenol oxidase (PPO) (340%) activities compared to their controls. Our findings revealed that NPK is an important nutrient-based fertilizer for plant growth and development. However, its efficiency as a fertilizer is quite low. In addition, we highlighted different mechanisms mediated by AMF and compost, inducing drought tolerance in tomato plants.

Application of molecular dynamics simulation for exploring the roles of plant biomolecules in promoting environmental health

Understanding the dynamic changes of plant biomolecules is vital for exploring their mechanisms in the environment. Molecular dynamics (MD) simulation has been widely used to study structural evolution and corresponding properties of plant biomolecules at the microscopic scale. Here, this review (i) outlines structural properties of plant biomolecules, and the crucial role of MD simulation in advancing studies of the biomolecules; (ii) describes the development of MD simulation in plant biomolecules, determinants of simulation, and analysis parameters; (iii) introduces the applications of MD simulation in plant biomolecules, including the response of the biomolecules to multiple stresses, their roles in corrosive environments, and their contributions in improving environmental health; (iv) reviews techniques integrated with MD simulation, such as molecular biology, quantum mechanics, molecular docking, and machine learning modeling, which bridge gaps in MD simulation. Finally, we make suggestions on determination of force field types, investigation of plant biomolecule mechanisms, and use of MD simulation in combination with other techniques. This review provides comprehensive summaries of the mechanisms of plant biomolecules in the environment revealed by MD simulation and validates it as an applicable tool for bridging gaps between macroscopic and microscopic behavior, providing insights into the wide application of MD simulation in plant biomolecules.

Exogenous Calcium Reinforces Photosynthetic Pigment Content and Osmolyte, Enzymatic, and Non-Enzymatic Antioxidants Abundance and Alleviates Salt Stress in Bread Wheat

One of the main environmental stresses that hinder crop development as well as yield is salt stress, while the use of signal molecules such as calcium (Ca) has a substantial impact on reducing the detrimental effects of salt on different crop types. Therefore, a factorial pot experiment in a completely randomized design was conducted to examine the beneficial role of Ca (0, 2.5, and 5 mM) in promoting the physiological, biochemical, and growth traits of the wheat plant under three salt conditions viz. 0, 30, and 60 mM NaCl. Foliar application of Ca increased the growth of salt-stressed wheat plants through increasing photosynthetic pigments, IAA, proline, and total soluble sugars contents and improving antioxidant enzymes in addition to non-enzymatic antioxidants glutathione, phenol and flavonoids, β-carotene, and lycopene contents, thus causing decreases in the over-accumulation of free radicals (ROS). The application of Ca increased the activity of antioxidant enzymes in wheat plants such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), which scavenge reactive oxygen species (ROS) and relieved salt stress. An additional salt tolerance mechanism by Ca increases the non-antioxidant activity of plants by accumulating osmolytes such as free amino acids, proline, and total soluble sugar, which maintain the osmotic adjustment of plants under salinity stress. Exogenous Ca application is a successful method for increasing wheat plants' ability to withstand salt stress, and it has a considerable impact on the growth of wheat under salt stress.

Metabolomic Analysis Reveals the Effect of Insecticide Chlorpyrifos on Rice Plant Metabolism

Pesticides as important agricultural inputs play a vital role in protecting crop plants from diseases and pests; however, the effect of pesticides on crop plant physiology and metabolism is still undefined. In this study, the effect of insecticide chlorpyrifos at three doses on rice plant physiology and metabolism was investigated. Our results revealed that chlorpyrifos cause oxidative stress in rice plants and even inhibit plant growth and the synthesis of protein and chlorophyll at high doses. The metabolomic results suggested that chlorpyrifos could affect the metabolic profiling of rice tissues and a total of 119 metabolites with significant changes were found, mainly including organic acids, amino acids, lipids, polyphenols, and flavonoids. Compared to the control, the content of glutamate family amino acids were significantly disturbed by chlorpyrifos, where defense-related proline and glutathione were significantly increased; however, glutamic acid, N-acetyl-glutamic acid and N-methyl-glutamic acid were significantly decreased. Many unsaturated fatty acids, such as linolenic acid and linoleic acid, and their derivatives lysophospholipids and phospholipids, were significantly accumulated in chlorpyrifos groups, which could act as osmolality substances to help rice cells relieve chlorpyrifos stress. Three organic acids, aminobenzoic acid, quinic acid, and phosphoenolpyruvic acid, involved in plant defenses, were significantly accumulated with the fold change ranging from 1.32 to 2.19. In addition, chlorpyrifos at middle- and high-doses caused the downregulation of most flavonoids. Our results not only revealed the effect of insecticide chlorpyrifos on rice metabolism, but also demonstrated the value of metabolomics in elucidating the mechanisms of plant responses to stresses.

Effect of Stress Signals and Ib-rolB/C Overexpression on Secondary Metabolite Biosynthesis in Cell Cultures of Ipomoea batatas

Ipomoea batatas is a vital root crop and a source of caffeoylquinic acid derivatives (CQAs) with potential health-promoting benefits. As a naturally transgenic plant, I. batatas contains cellular T-DNA (cT-DNA) sequence homologs of the Agrobacterium rhizogenes open reading frame (ORF)14, ORF17n, rooting locus (Rol)B/RolC, ORF13, and ORF18/ORF17n of unknown function. This study aimed to evaluate the effect of abiotic stresses (temperature, ultraviolet, and light) and chemical elicitors (methyl jasmonate, salicylic acid, and sodium nitroprusside) on the biosynthesis of CQAs and cT-DNA gene expression in I. batatas cell culture as a model system. Among all the applied treatments, ultraviolet irradiation, methyl jasmonate, and salicylic acid caused the maximal accumulation of secondary compounds. We also discovered that I. batatas cT-DNA genes were not expressed in cell culture, and the studied conditions weakly affected their transcriptional levels. However, the Ib-rolB/C gene expressed under the strong 35S CaMV promoter increased the CQAs content by 1.5-1.9-fold. Overall, our results show that cT-DNA-encoded transgenes are not involved in stress- and chemical elicitor-induced CQAs accumulation in cell cultures of I. batatas. Nevertheless, overaccumulation of RolB/RolC transcripts potentiates the secondary metabolism of sweet potatoes through a currently unknown mechanism. Our study provides new insights into the molecular mechanisms linked with CQAs biosynthesis in cell culture of naturally transgenic food crops, i.e., sweet potato.