Relative Membrane Permeability Research Articles

Effects of SNP, MgSO4, and MgO-NPs foliar application on Spinacia oleracea L. growth and physio-biochemical responses under cadmium stress

The effects of foliar application of sodium nitroprusside (SNP), magnesium sulfate (MgSO4) and magnesium oxide nanoparticles (MgO-NPs) on the growth, physiology, and gas exchange parameters of two varieties of spinach (Spinacia oleracea L.) under cadmium (Cd) stress were examined. The experiment was arranged in a completely randomized design with 72 pots. Two varieties of S. oleracea (Desi Palak & Lahori Palak) were used. Two concentrations of Cd (0 µM and 150 µM) in the form of cadmium chloride (CdCl2) were used. Two levels of SNP (0 ppm and 100 ppm) and two levels for each form of Mg i.e. MgSO4 and MgO-NPs (0 and 200 ppm) were foliar sprayed on plants in control and Cd stress. Both varieties behaved similarly under Cd stress and caused reductions in growth, physiology, gas exchange, water content parameters and inorganic ion uptake. However, the biochemical parameters like relative membrane permeability (RMP), malondialdehyde (MDA), and hydrogen peroxide (H2O2) contents were increased. However, all foliar spray treatments increased growth, physiological and gas exchange parameters, water content and inorganic ion uptake. However, this reduced the MDA, RMP, and H2O2 contents. Desi Palak showed the more positive results under foliar application of MgO-NPs. However, Lahori palak showed more positive results under the SNP + MgO-NP treatment. It is concluded that foliar application of SNP, MgSO4 and MgO-NPs could be an innovative approach to alleviated the heavy metals (Cd) toxicity in crop plants.

Comparative Physiological and Gene Expression Analyses Reveal Mechanisms Involved in Maintaining Photosynthesis Capacity, Alleviating Ion Toxicity and Oxidative Stress of Kentucky Bluegrass under NaCl Treatment.

Kentucky bluegrass (Poa pratensis L.), a widely used cool-season turfgrass, shows a high sensitivity to soil salinity. Clarifying the adaptative mechanisms of Kentucky bluegrass that serve to improve its salt tolerance in saline environments is urgent for the application of this turfgrass in salt-affected regions. In this study, physiological responses of the Kentucky bluegrass cultivars "Explorer" and "Blue Best" to NaCl treatment, as well as gene expressions related to photosynthesis, ion transport, and ROS degradation, were analyzed. The results showed that the growth of "Explorer" was obviously better compared to "Blue Best" under 400 mM NaCl treatment. "Explorer" exhibited a much stronger photosynthetic capacity than "Blue Best" under NaCl treatment, and the expression of key genes involved in chlorophyll biosynthesis, photosystem II, and the Calvin cycle in "Explorer" was greatly induced by salt treatment. Compared with "Blue Best", "Explorer" could effectively maintain Na+/K+ homeostasis in its leaves under NaCl treatment, which can be attributed to upregulated expression of genes, such as HKT1;5, HAK5, and SKOR. The relative membrane permeability and contents of O2- and H2O2 in "Explorer" were significantly lower than those in "Blue Best" under NaCl treatment, and, correspondingly, the activities of SOD and POD in the former were significantly higher than in the latter. Moreover, the expression of genes involved in the biosynthesis of enzymes in the ROS-scavenging system of "Explorer" was immediately upregulated after NaCl treatment. Additionally, free proline and betaine are important organic osmolytes for maintaining hydration status in Kentucky bluegrass under NaCl treatment, as the contents of these metabolites in "Explorer" were significantly higher than in "Blue Best". This work lays a theoretical basis for the improvement of salt tolerance in Kentucky bluegrass.

Pervasive influence of heavy metals on metabolic pathways is potentially relieved by hesperidin to enhance the phytoremediation efficiency of Bassia scoparia.

Hesperidin (HSP), a flavonoid, is a potent antioxidant, metal chelator, mediator of signaling pathways, and regulator of metal uptake in plants. The study examined the ameliorative effects of HSP (100 μM) on Bassia scoparia grown under excessive levels of heavy metals (zinc (500 mg kg-1), copper (400 mg kg-1), cadmium (100 mg kg-1), and chromium (100 mg kg-1)). The study clarifies the underlying mechanisms by which HSP lessens metabolic mayhem to enhance metal stress tolerance and phytoremediation efficiency of Bassia scoparia. Plants manifested diminished growth because of a drop in chlorophyll content and nutrient acquisition, along with exacerbated deterioration of cellular membranes reflected in elevated reactive oxygen species (ROS) production, lipid peroxidation, and relative membrane permeability. Besides the colossal production of cytotoxic methylglyoxal, the activity of lipoxygenase was also higher in plants under metal toxicity. Conversely, hesperidin suppressed the production of cytotoxic ROS and methylglyoxal. Hesperidin improved oxidative defense that protected membrane integrity. Hesperidin caused a more significant accumulation of osmolytes, non-protein thiols, and phytochelatins, thereby rendering metal ions non-toxic. Hydrogen sulfide and nitric oxide endogenous levels were intricately maintained higher in plants treated with HSP. Hesperidin increased metal accumulation in Bassia scoparia and thereby had the potential to promote the reclamation of metal-contaminated soils.

Effect of hesperidin on growth, photosynthesis, antioxidant systems and uptake of cadmium, copper, chromium and zinc by Celosia argentea plants

Rapid industrialization and extensive agricultural practices are the major causes of soil heavy metal contamination, which needs urgent attention to safeguard the soils from contamination. However, the phytotoxic effects of excessive metals in plants are the primary obstacle to efficient phytoextraction. The present study evaluated the effects of hesperidin (HSP) on metals (Cu, Cd, Cr, Zn) phytoextraction by hyperaccumulator (Celosia argentea L.) plants. For this purpose, HSP, a flavonoid compound with strong antioxidant potential to assist metal phytoextraction was used under metal stress in plants. Celosia argentea plants suffered significant (P ≤ 0.001) oxidative damage due to the colossal accumulation of metals (Cu, Cd, Cr, Zn). However, HSP supplementation notably (P ≤ 0.001) abated ROS generation (O2•‒, •OH, H2O2), lipoxygenase activity, methylglyoxal production, and relative membrane permeability that clearly indicated HSP-mediated decline in oxidative injury in plants. Exogenous HSP improved (P ≤ 0.001) the production of non-protein thiol, phytochelatins, osmolytes, and antioxidant compounds. Further, HSP enhanced (P ≤ 0.001) H2S and NO endogenous production, which might have improved the GSH: GSSG ratio. Consequently, HSP-treated C. argentea plants had higher biomass alongside elevated metal accumulation mirrored as profound modifications in translocation factor (TF), bioaccumulation coefficient (BAC), and bioconcentration factor (BCF). In this context, HSP significantly enhanced TF of Cr (P ≤ 0.001), Cd (P ≤ 0.001), and Zn (P ≤ 0.01), while BAC of Cr (P ≤ 0.001), Cd (P ≤ 0.001), and Zn (P ≤ 0.001). Further, BCF was significant (P ≤ 0.05) only in plants grown under Cr-spiked soil. Overall, HSP has the potential for phytoremediation of metals by C. argentea, which might be a suitable strategy for metal-polluted soils.

Bio-inoculation with Serratia CP-13 enhances Cd detoxification via modulation of phytohormone, gas exchange attributes and nutrient acquisition in maize cultivars cultivated in Cd-stressed soil

Heavy metals contamination of soil is increasing rapidly due to prompt in urbanization and industrialization. Recently, cadmium (Cd) pollution has emerged as a severe menace to plant and human health, while the use of plant growth promoting rhizobacteria (PGPR) has appeared as an economical approach for bioremediation of Cd toxicity in crop plants. In this study, the effect of Serratia sp. CP-13 inoculation on two maize cultivars in pre-Cd (0, 5, 12, 18, 26, 30 µM) spiked soil was evaluated. The combined effect of soil Cd and CP-13 application was assessed through the analysis of seed germination, plant biomass, phytohormones, gas exchange attributes, antioxidant production, plant Cd, and nutrient uptake in two (Sahiwal-2002, MMRI-Yellow) maize cultivars. Our outcomes exposed that single treatment of Cd-spiked soil significantly downregulates seed germination, plant biomass, plant nutrients, photosynthetic pigments, indole acetic acid (IAA), total protein, proline, total soluble sugar (TSS), stomatal conductance, transpiration rate, net photosynthesis, and antioxidant production, together with upregulating malondialdehyde (MDA), relative membrane permeability (RMP), abscisic acid (ABA), and Cd uptake in maize cultivars. However, this response of the maize crop against Cd-spiked soil was found to be maximal in Sahiwal-2002 at 30 µM Cd. Furthermore, the inoculation of Cd-resistant CP-13 significantly upregulates the plant accumulation of biomass, seed germination, antioxidants, IAA, gas exchange attributes, photosynthetic pigments, plant physiology, and nutrient uptake and downregulates the MDA, RMP, ABA, and root/shoot Cd accretion in two cultivars of maize. Moreover, this CP-13 based upregulation of plant growth was found to be cultivar (Sahiwal-2002) and Cd treatment (30 µM) specific by controlling the accumulation of lipid peroxidation, phytohormone content, and Cd detoxification. Further, our results indicate that the CP-13 might be a promising and cost effective future biofertilizer for bioremediation of soil Cd.

Coumarin regulated redox homeostasis to facilitate phytoremediation of saline and alkaline soils by bitter gourd (Momordica charantia L.).

The use of coumarin (COU) to alleviate the phytotoxic effects of salinity has great potential in improving the phytoremediation of saline and alkaline soils. 30-day bitter gourd plants were exposed to 15 dS m‒1 salinity of neutral (NaCl and Na2SO4) and alkaline (Na2CO3 and NaHCO3) salts. 60-day plants were harvested to record different growth, physiological and biochemical attributes. Salinity significantly subsided plant growth, chlorophyll, photosynthesis, and nutrient acquisition. Salinity induced notable oxidative damage in plants that displayed higher relative membrane permeability (RMP), accumulated elevated ROS (H2O2 and O2•‒) and MDA levels alongside intensified lipoxygenase (LOX) activity. The production of cytotoxic methylglyoxal was also significantly higher in plants under salinity. COU seed priming (50, 100 and 150mg L‒1) promoted plant growth by circumventing oxidative injury and intensifying oxidative defense. Further, COU maintained the intricate balance between reduced (GSH) and oxidized (GSSG) glutathione to diminish ion excess toxicity, thereby facilitating the phytoremediation of saline soils. The lower doses of COU promoted methylglyoxal and ROS detoxification systems that, in turn, lessened the phytotoxic effects of salinity. COU restored ions homeostasis by augmenting osmotic adjustment in plants under salinity.

Effect of seed priming by taurine on growth and chromium (Cr) uptake in canola (Brassica napus L.) under Cr stress.

Taurine is a recently recognized plant growth regulator under abiotic stress. However, the information on taurine-mediated plant defense responses is scarce, particularly on taurine-mediated regulation of the glyoxalase system. There is currently no report available on the use of taurine as seed priming under stress. Chromium (Cr) toxicity considerably subsided growth characteristics, photosynthetic pigments, and relative water content. Furthermore, plants encountered intensified oxidative injury due to a significant increase in relative membrane permeability, H2O2, O2•‒, and MDA production. The amount of antioxidant compounds and the functioning of antioxidant enzymes rose, but imbalance due to over ROS generation frequently depleted antioxidant compounds. Taurine seed priming (50, 100, 150, and 200mg L‒1) notably diminished oxidative injury, strengthened the antioxidant system, and conspicuously subsided methylglyoxal levels through enhanced activities of glyoxalase enzymes. The accumulation of Cr content was minimal in plants administered taurine as seed priming. In conclusion, our research demonstrates that taurine priming effectively mitigated the adverse effects of Cr toxicity on canola. Taurine reduced oxidative damage, leading to improved growth, enhanced chlorophyll levels, optimized ROS metabolism, and enhanced methylglyoxal detoxification. These findings highlight the potential of taurine as a promising strategy to enhance the tolerance of canola plants to Cr toxicity.

Putrescine transformation to other forms of polyamines in filling grain embryos functioned in enhancing the resistance of maize plants to drought stress

Polyamines (PAs), one of plant growth regulators, play an important role in the plant resistance to drought stress. However, the precise function of putrescine (Put) transformation to other forms of PAs is not clear in filling maize grain embryos. In this study, two maize (Zea mays L.) cultivars, Yedan No. 13 (drought-resistant) and Xundan No. 22 (drought-sensitive), were used as experimental materials. Maize was planted in big plastic basins during whole growth period, and from the 25th day after fertilization, the plants were treated with drought (−1.0 MPa), PAs and inhibitors for 12 d. The experiments were performed during three consecutive years. The changes in the levels of three main free PAs, Put, spermidine (Spd) and spermine (Spm), covalently conjugated PAs (perchloric acid-soluble), covalently bound PAs (perchloric acid-insoluble), the activities of arginine decarboxylase, S-adenosylmethionine decarboxylase, and transglutaminase were investigated in embryos of filling grains. During drought stress, free Put increased from 109 to 367 nmol g−1 FW and from 107 to 142 nmol g−1 FW in Xundan 22 and in Yedan 13, respectively. Meanwhile, free Spd, free Spm and bound Put increased 2.7, 3.0 and 4.2 times in Yedan 13, respectively, and they merely increased about 1.5 times in Xundan 22. These results suggested that free Spd/Spm and bound Put, which were transformed from free Put, were possibly involved in drought resistance. Exogenous Spd treatment enhanced the drought-induced increase in endogenous free Spd/Spm content in drought-sensitive Xundan 22, coupled with the increase in drought resistance, as judged by the decrease in ear leaf relative plasma membrane permeability and increases in ear leaf relative water content, 1000-grain weight and grain number per ear. The suggestion was further testified with methylglyoxal-bis guanylhydrazone and o-phenanthrolin treatments. Collectively, it could be inferred that transformation of free Put to free Spd/Spm and bound Put in filling grain embryos functioned in enhancing the resistance of maize plants to soil drought.

Seed treatments with salicylic and succinic acid to mitigate drought stress in flowering kale cv. 'Red Pigeon F1'

Drought, which is increasingly in important worldwide because of climate change, has also become an existential threat to bedding plants. This study aimed to determine the effect of salicylic and succinic acid on the physiological and biochemical traits of flowering kale plants grown under drought stress. Seeds of the Brassica oleracea (Acephala group) cv. 'Red Pigeon F1′ were used as plant material. The seeds were treated with 3 different concentrations of succinic acid (0.5 mM, 1.0 mM, and 2.0 mM) and salicylic acid (0.5 mM, 1.0 mM, 2.0 mM). In the early seedling stage, the untreated seedlings (the negative control) and seedlings treated with succinic and salicylic acid were exposed to severe drought stress conditions while the positive control (no treatment) was watered to 100% of its field capacity. The experiment was terminated when symptoms of drought stress were observed in 50% of the seedlings in the negative control group. Relative chlorophyll content, stomatal conductance, leaf temperature, leaf relative water content, leaf area, membrane permeability, lipid peroxidation, proline content and antioxidant enzyme activity were recorded. As a result of the study, succinic and salicylic acid were found to be effective in countering stress mechanisms of flowering kale seedlings. The MDA content (58.56 nmol g−1 FW) and membrane injury (43.12%) reached the highest value in untreated seedlings under drought conditions. Antioxidant enzyme activities, relative chlorophyll content and proline content of seedlings treated with succinic and salicylic acid were higher than both the negative control and positive control. The 2.0 mM succinic acid and 2.0 mM salicylic acid treatments improved the stomatal conductance by 69.39% and 68.43%. Leaf relative water content was also better in drought-stressed seedlings treated with succinic and salicylic acid compared to the negative control. The results of the study showed that drought stress tolerance increased in flowering kale after both salicylic and succinic acid treatments. Succinic acid can be an elicitor candidate and it might be used to increase stress tolerance in plants.

Effect of exogenous taurine on pea (Pisum sativum L.) plants under salinity and iron deficiency stress

Soil salinity and Fe deficiency affect plant growth and survival by changing nutrient availability and disrupting water balance. Natural and human activities, such as evaporation and deforestation, can intensify these soil conditions. Taurine, a novel growth regulator, holds promise in mediating plant defense responses. Its effects on defense responses are still unclear. Previously, taurine showed potential in improving clover tolerance to alkaline stress and manganese toxicity. Taurine impact on plant growth under Fe deficiency and salinity stress remains uninvestigated. A pot experiment was conducted to evaluate the effects of taurine on pea plant growth, ion uptake, and defense strategies in response to salt stress and Fe deficiency. Iron deficiency was established by substituting 0.1 mM FeSO4 for 0.1 mM Fe-EDTA in the nutrient solution. Salinity stress was induced by incorporating a mixture of NaCl, MgCl2, KCl, Na2SO4, Na2CO3, NaHCO3 and CaCl2 in a 1:1:1:1:1:1:1 ratio to produce a salinity concentration of 100 mM. The simultaneous imposition of salinity and Fe deficiency significantly exacerbated oxidative stress, as evidenced by elevated levels of relative membrane permeability, hydrogen peroxide (H2O2), superoxide radical (O2•−), methylglyoxal (MG), malondialdehyde (MDA), and increased activity of lipoxygenase (LOX). Salinity stress alone and the combination of salinity and Fe deficiency resulted in substantial accumulation of Na+ ions that impeded acquisition of essential nutrients. Taurine (100 and 200 mg L−1) notably improved osmotic adjustment and oxidative defense to diminish water imbalance and oxidative injury in plants under stress. These results suggest that exogenous taurine may serve as a promising means of mitigating the detrimental effects of salt stress and Fe deficiency in plants.

Flowering Time and Physiological Reaction of Dendrobium nobile Lindl in Response to TDZ Application

The objective of this work was to analyze the effect of Thidiazuron (TDZ) treatment on floral initiation, flowering time, ornamental characteristics and physiological metabolism of potted Dendrobium nobile. Three TDZ concentrations (200, 500 and 1000 mg L−1) were applied as solution to water the root zone of the plants. Control plants (plants watered with water) showed a good vegetative development but no floral branches. TDZ greatly influenced the flowering process. For all the tested TDZ concentrations, the first flower bud occurred at 55–60 days after the last irrigation (DAI), the highest TDZ concentration showing the major delay in its occurrence. The initial flowering (30% of flowered plants) began 47 days after the first flower bud initiation with no statistical differences among the treatments. Plants treated with TDZ 500–1000 mg L−1 showed the longest period of flowering (about 32 days) and the single flowers delayed the withering of about 2–3 days compared to the lowest TDZ treatment (200 mg L−1). The number of flowers, floral branches and flowering percentage were distinctly influenced by the TDZ concentration. The highest percentage of flowering (40%) was scored when plants were watered with a TDZ solution at 500 mg L−1 and this was a performant treatment providing the best morphological flower features for the ornamental value of this plant. Among the physiological factors affecting the flowering, this study showed that TDZ increased the relative membrane permeability which facilitated the transport of macromolecular flower-forming substances into and out of the membrane. Therefore, the membrane permeability change could be an indicator of shifts in physiologically active substances during the flowering transition process in Dendrobium nobile plants.

Exogenous α-Tocopherol Regulates the Growth and Metabolism of Eggplant (Solanum melongena L.) under Drought Stress.

The present investigation was designed to improve drought stress tolerance in eggplant (Solanum melongena L.) through the exogenous application of α-tocopherol (TOC). For exogenous application, two modes, i.e., foliar spray (FS) and pre-sowing seed treatment (PS), were used. Water deficiency treatment (50% field capacity (FC)) was applied on 32-day-old seedlings of two eggplant cultivars, i.e., Janak and Black Beauty. Five levels of TOC (0 mg/L, 50 mg/L PS, 100 mg/L PS, 50 mg/L FS, and 100 mg/L FS) were applied as PS and FS. Pre-sowing seed treatment was conducted before seed sowing, while FS treatment after 30 days of drought stress treatment. After 15 days of TOC as an FS application, it was observed that drought stress significantly reduced plant growth (5-15%) and chlorophyll contents (4-10%), while it increased proline (4-6%), glycine betaine (GB) (5-10%), malondialdehyde (MDA) (10.8%), hydrogen peroxide (15-16%), relative membrane permeability (RMP) (5-8%), and the activities of peroxidase (7-8%) and superoxide dismutase (12-15%) in both eggplant cultivars. The TOC application (FS and PS) exhibited a positive role in overcoming the adverse effect of water stress on eggplants. Plant growth increased (15-18%) as a result of the application of TOC, which could be linked with improved chlorophyll, ascorbic acid (AsA), GB, proline, total soluble proteins (TSP), and the activities of peroxidase (POD) and superoxide dismutase (SOD) activities. The reactive oxygen species H2O2 was also decreased by TOC application. Overall, TOC as a foliar spray was more effective in improving the accumulation of proline, GB, AsA, and activities of SOD and POD enzymes, while PS treatment was more effective in reducing RMP and improving the TSP of eggplant. Cv. Black Beauty was comparatively better in root dry weight, chlorophyll a and b, and MDA contents, while cv. Janak in RMP, AsA, TSP, and activity of the POD enzyme. It can be inferred that the application of TOC was useful in counteracting the harmful effects of drought stress on both cultivars of eggplants.

AtVIP1 AND GsNAC2 ENHANCE SALINE-ALKALI STRESS TOLERANCE BY PROMOTING PLANT GROWTH AND INDUCING STRESS RESPONSE GENE DURING THE GERMINATION PERIOD OF SORGHUM

The quality and yields of Sorghum bicolor (L.) plants are seriously affected by saline-alkali conditions. VIP, and NAC (NAM, ATAF, and CUC) transcription factors are specific, and have various functions in plant development and response to various stresses. To study the tolerance to saline-alkali stress of transgenic sorghum overexpressed by AtVIP1 and GsNAC2 genes, sorghum seeds were treated with stress solution (NaHCO3: Na2CO3 = 5: 1, 75 mM, pH 9.63). After the stress treatment, the growth morphological indexes, stress-resistant physiological indexes and stress-related gene expression levels of sorghum buds were measured. The results show that the transgenic sorghum with overexpressing AtVIP1 and GsNAC2 genes had a higher bud length, fresh weight, and moisture content. Compared to the control, lower H2O2 and O2- levels, relative permeability of the plasma membrane, and MDA content, with higher POD, CAT, and SOD activities were found in transgenic sorghum. Gene expression analysis revealed that several stress response genes were up-regulated. Furthermore, these results suggest that AtVIP1 and GsNAC2 gene play potentially important roles in response to saline-alkali stress, and may be used in breeding new varieties to improve sorghum yields under adverse environmental conditions.

GsNAC2 gene enhances saline-alkali stress tolerance by promoting plant growth and regulating glutathione metabolism in Sorghum bicolor.

The quality and yields of Sorghum bicolor plants are seriously affected by saline-alkali conditions. NAC (NAM, ATAF, and CUC) transcription factors are plant specific and have various functions in plant development and response to various stresses. To investigate how GsNAC2 functions in sorghum responses to saline-alkali treatment, the characteristics of GsNAC2 were analysed by bioinformatics methods, and NaHCO3:Na2CO3 (5:1, 75mM, pH 9.63) saline-alkali stress solution was applied when sorghum plants were 2weeks old. The research results show that GsNAC2 belongs to the NAC gene family. GsNAC2 was significantly induced by saline-alkali treatment and strongly expressed in sorghum leaves. GsNAC2-overexpressing sorghum plants had increased plant height, dry weight, moisture content, root activity, leaf length, chlorophyll content, stomatal conductance, relative root activity, relative chlorophyll content, relative stomatal conductance, and relative transpiration rate after saline-alkali treatment. Lower H2O2 and O2- levels, relative permeability of the plasma membrane, and malondialdehyde (MDA) content were found in GsNAC2-overexpressing sorghum. In transcriptome analysis, clusters of orthologous groups (COG) analysis showed that a high proportion of differentially-expressed genes (DEGs) participated in defence mechanisms at each processing time, and 18 DEGs related to synthetic glutathione were obtained. Gene expression analysis revealed that key genes in glutathione biosynthesis pathways were upregulated. GR and GSH-Px activities were increased, and GSH accumulated more with the overexpression of GsNAC2 after saline-alkali treatment. Furthermore, these results suggest that GsNAC2 acts as a potentially important regulator in response to saline-alkali stress and may be used in molecular breeding to improve crop yields under adverse environmental conditions.

Induction of salt tolerance in Brassica rapa by nitric oxide treatment.

Salinity is one of the major plant abiotic stresses increasing over time worldwide. The most important biological role of nitric oxide (NO) in plants is related to their development and growth under abiotic conditions. The present experiment was conducted to study the effect of salt stress (0 and 100mM) and NO (0 and 80μM) on two different ecotypes of Brassica rapa (L.): PTWG-HL and PTWG-PK. The different growth attributes, biochemical and physiological parameters, and the mineral contents were examined. The results indicated increased hydrogen peroxide (H2O2), relative membrane permeability, malondialdehyde (MDA), and Na+ content and decreased plant biomass in both ecotypes (PTWG-PK and PTWG-HL) under salt stress. In contrast, NO treatment resulted in increased plant biomass, chlorophyll content, and total soluble proteins and decreased H2O2, relative membrane permeability, MDA, total phenolic content, catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and Na+. The combined effect of salt stress and NO application increased the chlorophyll a content, total phenolic content, and total soluble proteins, but decreased H2O2, relative membrane permeability, MDA, and Na+. The response of carotenoids, anthocyanins, and K+, Ca2+, and Cl- ions varied in both ecotypes under all treatment conditions. The PTWG-PK ecotype showed maximum overall growth response with the application of NO. Henceforth, it is proposed that the molecular mechanisms associated with NO-induced stress tolerance in plants may be exploited to attain sustainability in agriculture under changing climate scenarios.

Trehalose-Induced Regulations in Nutrient Status and Secondary Metabolites of Drought-Stressed Sunflower (Helianthus annuus L.) Plants.

Trehalose regulates key physio-biochemical parameters, antioxidants, and the yield of plants exposed to a dry environment. A study was conducted to assess the regulatory roles of exogenously applied trehalose in drought-stressed sunflower plants. Two cultivars of sunflowers (Hysun 33 and FH 598) were subjected to drought stress (60% field capacity) and varying (0, 10, 20, and 30 mM) concentrations of trehalose. The data indicated that water stress significantly reduced the shoot length, root length, total soluble proteins, shoot Ca2+, root P, relative water content (RWC), and achene yield per plant. The foliar spray of trehalose was effective at improving plant growth, RWC, total soluble proteins, total soluble sugars, the activities of enzymatic antioxidants, Ca2+ (shoot and root), root K+, and the yield attributes. Exogenously supplemented trehalose considerably suppressed relative membrane permeability (RMP), but did not alter ascorbic acid, malondialdehyde, the total phenolics, shoot K+, or P (shoot and root) in both sunflower cultivars. The cv. Hysun 33 had better ascorbic acid, total soluble sugars, non-reducing sugars, shoot P, and root P than the other cultivar, whereas cv. FH 598 was relatively better at regulating RMP, malondialdehyde, peroxidase, and root Ca2+ concentration. Overall, exogenously supplemented trehalose, particularly at 10 mM, was effective at improving the physiochemical parameters and yield of sunflower plants under stress conditions. Therefore, a better performance of sunflower cv. Hysun 33 under drought stress can be suggested as a trehalose-induced enhancement of yield and oxidative defense potential.

Exogenous Nitric Oxide and Silicon Applications Alleviate Water Stress in Apricots.

Many plants confront several environmental stresses including heat, water stress, drought, salinity and high-metal concentrations that are crucial in defining plant productivity at different stages of their life cycle. Nitric oxide (NO) and Silicon (Si) are very effective molecules related in most of them and in varied biochemical events that have proven to be protective during cellular injury caused by some stress conditions like water stress. In the current work, we studied the effect of Si and NO alone and NO + Si interactive application on the response of plants exposed to water deficiency and well-watered plants for the Milord apricot variety. Water stress caused a reduce in chlorophyll content, dry and fresh weight, leaf area, stomatal conductivity, leaf relative water content and nutrient elements, while it caused an increase in leaf temperature, leaf proline, leaf malondialdehyde (MDA) content and membrane permeability. Si, NO and Si + NO combination treatments under water stress conditions significantly decreased the adverse effects of water stress on leaf temperature, leaf area, dry and fresh weight, stomata conductivity, relative water content, membrane permeability, L-proline and MDA content. The shoot dry weight, chlorophyll content, stomata conductivity and leaf relative water content in Si + NO treated apricot saplings increased by 59%, 55%, 12% and 8%, respectively. Combined treatment (Si + NO) was detected to be more effective than single applications (Si or NO) on some physiological, biochemical, morphological and nutritional properties of apricot under water stress conditions.

Agro-morphological, physiological and biochemical performances of two new durum wheat cultivars under salt stress conditions

Soil salinization requires developing genetically salt-tolerant and high-yielding genotypes, especially in semi-arid and arid regions. In this study, two new Tunisian durum wheat cultivars, INRAT100 and Dhahbi, were tested for the first time in a semi-closed environment against salinity (0, 6 and 12 dS m-1). Dry weight of aerial and root parts, plant height, number of tillers per plant, spike and awn length, grain yield and its components, relative water content, relative membrane permeability, chlorophyll content, leaf chlorophyll fluorescence, i.e., initial fluorescence (F0) and the quantum yield of photosystem II (Fv/Fm), potassium (K+) and sodium (Na+) accumulation and the ratio K+/Na+ were assessed. Overall, most of growth and yield performance, physiological and biochemical attributes were affected by salinity. Notably, INRAT100 was characterized by a higher K+ content, K+/Na+ ion selectivity, relative water content and Fv/Fm, grain yield and lower membrane permeability than that of Dhahbi under saline conditions. However, Dhahbi exhibited higher spike and awn length and a number of spikelets per spike. These findings suggest that INRAT100 is more tolerant to salinity than Dhahbi and might be recommended to farmers of marginal environments.

Synthesis of γ-Aminobutyric Acid-Modified Chitooligosaccharide Derivative and Enhancing Salt Resistance of Wheat Seedlings.

Salinity is one of the major abiotic stresses limiting crop growth and productivity worldwide. Salt stress during germination degenerates crop establishment and declines yield in wheat, therefore alleviating the damage of salt stress to wheat seedlings is crucial. Chitooligosaccharide (COS) was grafted with γ-aminobutyric acid based on the idea of bioactive molecular splicing, and the differences in salt resistance before and after grafting were compared. The expected derivative was successfully synthesized and exhibited better salt resistance-inducing activity than the raw materials. By activating antioxidant enzymes such as superoxide dismutases (SOD), catalase (CAT) and phenylalanine ammonia-lyase (PAL) and subsequently eliminating reactive oxygen species (ROS) in a timely manner, the rate of O−2 production and H2O2 content of wheat seedlings were reduced, and the dynamic balance of free radical metabolism in the plant body was maintained. A significantly reduced MDA content, reduced relative permeability of the cell membrane, and decreased degree of damage to the cell membrane were observed. A significant increase in the content of soluble sugar, maintenance of osmotic regulation and the stability of the cell membrane structure, effective reduction in the salt stress-induced damage to wheat, and the induction of wheat seedling growth were also observed, thereby improving the salt tolerance of wheat seedlings.

Transcriptomic Profiling Provides Molecular Insights Into Hydrogen Peroxide-Enhanced Arabidopsis Growth and Its Salt Tolerance.

Salt stress is an important environmental factor limiting plant growth and crop production. Plant adaptation to salt stress can be improved by chemical pretreatment. This study aims to identify whether hydrogen peroxide (H2O2) pretreatment of seedlings affects the stress tolerance of Arabidopsis thaliana seedlings. The results show that pretreatment with H2O2 at appropriate concentrations enhances the salt tolerance ability of Arabidopsis seedlings, as revealed by lower Na+ levels, greater K+ levels, and improved K+/Na+ ratios in leaves. Furthermore, H2O2 pretreatment improves the membrane properties by reducing the relative membrane permeability (RMP) and malonaldehyde (MDA) content in addition to improving the activities of antioxidant enzymes, including superoxide dismutase, and glutathione peroxidase. Our transcription data show that exogenous H2O2 pretreatment leads to the induced expression of cell cycle, redox regulation, and cell wall organization-related genes in Arabidopsis, which may accelerate cell proliferation, enhance tolerance to osmotic stress, maintain the redox balance, and remodel the cell walls of plants in subsequent high-salt environments.