Calcium oxide nanoparticles mitigate lead stress in Abelmoschus esculentus though improving the key antioxidative enzymes, nutritional content and modulation of stress markers.

Lead (Pb) is thought to be one of most injurious metals on the earth. Lead stress in plants enhances synthesis of highly toxic reactive oxygen species (ROS). During present research, impact of calcium-oxide nanoparticles (CaO-NPs) was observed on antioxidative defense mechanism in Abelmoschus esculentus plants prone to Pb stress. A CRD experiment was employed with 5 replicates having four treatments (T0 = Control, T1 = Pb stress (200 ppm), T2 = CaO-NPs and T3 = Pb + CaO-NPs). Pb-stressed seedlings exhibited decreased root growth, shoot growth, chlorophyll concentration and biomass accumulation. Moreover, higher synthesis of hydrogen-peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) resulting in cellular injuries were noted in plants growing in Pb spiked conditions. Similarly, stressed plants showed higher accumulation of total soluble sugar and proline content besides elevated activity of antioxidative enzymes counting catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and ascorbate peroxidase (APX). On the contrary side, CaO-NPs alleviated the Pb induced phytotoxicity through improving activity of antioxidative enzymes. The elevated activity of antioxidant enzymes reduced biosynthesis of H2O2 and MDA which was revealed through the increased growth parameters. In addition, CaO-NPs persuaded enhancement in plant defence machinery by decreased chlorophyll deprivation and augmented the uptake of plant nutrients including K and Ca content. Hence, CaO-NPs can be potent regulators of the antioxidative enzymes and stress markers to ameliorate abiotic stresses.

28-Homobrassinolide Primed Seed Improved Lead Stress Tolerance in Brassica rapa L. through Modulation of Physio-Biochemical Attributes and Nutrient Uptake.

Brassinosteroids (BRs) influence a variety of physiological reactions and alleviate different biotic and abiotic stressors. Turnip seedlings were grown with the goal of further exploring and expanding their function in plants under abiotic stress, particularly under heavy metal toxicity (lead stress). This study's objective was to ascertain the role of applied 28-homobrassinolide (HBL) in reducing lead (Pb) stress in turnip plants. Turnip seeds treated with 1, 5, and 10 µM HBL and were grown-up in Pb-contaminated soil (300 mg kg-1). Lead accumulation reduces biomass, growth attributes, and various biochemical parameters, as well as increasing proline content. Seed germination, root and shoot growth, and gas exchange characteristics were enhanced via HBL treatment. Furthermore, Pb-stressed seedlings had decreased total soluble protein concentrations, photosynthetic pigments, nutrition, and phenol content. Nonetheless, HBL increased chlorophyll a and chlorophyll b levels in plant, resulting in increased photosynthesis. As a result, seeds treated with HBL2 (5 µM L-1) had higher nutritional contents (Mg+2, Zn+2, Na+2, and K+1). HBL2-treated seedlings had higher DPPH and metal tolerance indexes. This led to the conclusion that HBL2 effectively reduced Pb toxicity and improved resistance in lead-contaminated soil.

Exogenous application of glutathione enhanced growth, nutritional orchestration and physiochemical characteristics of Brassica oleracea L. under lead stress.

A major obstacle to agricultural production and yield quality is heavy metal contamination of the soil and water, which leads to lower productivity and quality of crops. The situation has significantly worsened as a result of the growing population and subsequent rise in food consumption. The growth of nutrient-rich plants is hampered by lead (Pb) toxicity in the soil. Brassica oleracea L. (broccoli) is a prominent vegetable crop in the Brassicaceae family subjected to a number of biotic and abiotic stresses that dramatically lower crop yields. Seed priming is a novel, practicable, and cost-effective method that can improve various abiotic stress tolerances. Many plant metabolic activities depend on the antioxidant enzyme glutathione (GSH), which also chelates heavy metals. Keeping in view the stress mitigation potential of GSH, current research work was designed to inspect the beneficial role of seed priming with GSH on the growth, morphological and gas exchange attributes of broccoli seedlings under Pb stress. For this purpose, broccoli seeds were primed with 25, 50, and 75 µM L-1 GSH. Plant growth and photosynthetic activity were adversely affected by Pb stress. Furthermore, Pb stress enhanced proline levels along with reduced protein and phenol content. The application of GSH improved growth traits, total soluble proteins, chlorophyll content, mineral content, and gas exchange parameters. The involvement of GSH in reducing Pb concentrations was demonstrated by an improved metal tolerance index and lower Pb levels in broccoli plants. The results of the current study suggest that GSH can be used as a strategy to increase broccoli tolerance to Pb by enhancing nutrient uptake, growth and proline.

Selenium-Priming mediated growth and yield improvement of turnip under saline conditions.

Salt toxicity is one of the foremost environmental stresses that declines nutrient uptake, photosynthetic activity and growth of plants resulting in a decrease in crop yield and quality. Seed priming has become an emergent strategy to alleviate abiotic stress and improve plant growth. During the current study, turnip seed priming with sodium selenite (Na2SeO3) was investigated for its ability to mitigate salt stress. Turnip (Brassica rapa L. var. Purple Top White Globe) seeds primed with 75, 100, and 125 µML-1 of Se were subjected to 200 mM salt stress under field conditions. Findings of the current field research demonstrated that salt toxicity declined seed germination, chlorophyll content, and gas exchange characteristics of B. rapa seedling. Whereas, Se-primed seeds showed higher germination rate and plant growth which may be attributed to the decreased level of hydrogen peroxide (H2O2) and malondialdehyde (MDA) decreased synthesis of proline (36%) and besides increased total chlorophyll (46%) in applied turnip plants. Higher expression levels of genes encoding antioxidative activities (CAT, POD, SO,D and APX) mitigated oxidative stress induced by the salt toxicity. Additionally, Se treatment decreased Na+ content and enhanced K+ content resulting in elevated K+/Na+ ratio in the treated plants. The in-silico assessment revealed the interactive superiority of Se with antioxidant enzymes including CAT, POD, SOD, and APX as compared to sodium chloride (NaCl). Computational study of enzymes-Se and enzymes-NaCl molecules also revealed the stress ameliorative potential of Se through the presence of more Ramachandran-favored regions (94%) and higher docking affinities of Se (-6.3). The in-silico studies through molecular docking of Na2SeO3, NaCl, and ROS synthesizing enzymes (receptors) including cytochrome P450 (CYP), lipoxygenase (LOX), and xanthine oxidase (XO), also confirmed the salt stress ameliorative potential of Se in B. rapa. The increased Ca, P, Mg, and Zn nutrients uptake nutrients uptake in 100 µML-1 Se primed seedlings helped to adjust the stomatal conductivity (35%) intercellular CO2 concentration (32%), and photosynthetic activity (41%) resulting in enhancement of the yield attributes. More number of seeds per plant (6%), increased turnip weight (115 gm) root length (17.24 cm), root diameter (12 cm) as well as turnip yield increased by (9%tons ha-1) were recorded for 100 µML-1 Se treatment under salinity stress. Findings of the current research judiciously advocate the potential of Se seed priming for salt stress alleviation and growth improvement in B. rapa.

According to our best of knowledge, it is the first time that seed primed with Selenium have been evaluated regarding NaCl stress mitigation in turnip. Salinity toxicity negatively affected physiochemical activities and growth of B.rapa.Seed priming with Selenium (Na₂SeO₃) mitigated salinity stress.Selenium (Se) enhanced nutrition, photosynthetic and antioxidant activity of applied plants.Selenium treated plants exhibited improved growth and reduced salinity content.

Burkholderia cepacia CS8 improves phytoremediation potential of Calendula officinalis for tannery solid waste polluted soil.

Microbes have shown potential for the bioremediation of tannery waste polluted soil. During our previous study, it was observed that heavy metal resistant Burkholderia cepacia CS8 augmented growth and phytoremediation capability of an ornamental plant. Objective of the present research work was to evaluate the capability of B. cepacia CS8 assisted Calendula officinalis plants for the phytoremediation of tannery solid waste (TSW) polluted soil. The TSW treatment significantly reduced growth attributes and photosynthetic pigments in C. officinalis. However, supplementation of B. cepacia CS8 which exhibited substantial tolerance to the TSW amended soil, augmented growth traits, carotenoid, proline, and antioxidant enzymes level in C. officinalis under toxic and nontoxic regimes. Inoculation of B. cepacia CS8 augmented plant growth (shoot length 13%, root length 11%), physiological attributes (chlorophyll a 14%, chlorophyll b 17%), antioxidant enzyme activities (peroxidase 24%, superoxide dismutase 31% and catalase 19%), improved proline 36%, phenol 32%, flavonoids 14% and declined malondialdehyde (MDA) content 15% and hydrogen peroxide (H2O2) level 12% in C. officinalis at TSW10 stress compared with relevant un-inoculated plants of TSW10 treatment. Moreover, B. cepacia CS8 application enhanced labile metals in soil and subsequent metal uptake, such as Cr 19%, Cd 22%, Ni 35%, Fe 18%, Cu 21%, Pb 34%, and Zn 30%, respectively in C. officinalis plants subjected to TSW10 stress than that of analogous un-inoculated treatment. Higher plant stress tolerance and improved phytoremediation potential through microbial inoculation will assist in the retrieval of agricultural land in addition to the renewal of native vegetation.

During the current study, it was observed that combination of Calendula officinalis and metal tolerant Burkholderia cepacia CS8 not only improved plant growth but also helped phyto-extraction of pollutants present in the tannery solid waste polluted soil. According to our information, research work describing the phytoremediation potential of native metal tolerant microbes and ornamental plants has not been reported in Pakistan.

Potassium silicate and zinc oxide nanoparticles modulate antioxidant system, membranous H+-ATPase and nitric oxide content in faba bean (Vicia faba) seedlings exposed to arsenic toxicity.

Current research focused on the potential role of zinc oxide nanoparticles (ZnONPs) and potassium (K+ ) in mitigation of arsenic (As) toxicity in Vicia faba L. seedlings. Faba bean seedlings were grown for 30days in potted soil. As stress curtailed root and shoot length, chlorophyll (Chl) content and net photosynthetic rate in V. faba seedlings. However, ZnONPs and K+ curtailed As stress in faba bean seedling through enhanced activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) enzyme. Furthermore, ZnONPs and K+ significantly enhanced cysteine (Cys) content and serine acetyletransferase (SAT) activity in faba bean seedling exposed to As-toxificated soil. Application of ZnONPs and K+ curtailed superoxide ionic content and hydrogen peroxide (H2 O2 ) accumulation in V. faba seedlings exposed to As-polluted soil. Nitric oxide (NO) content also increased in faba bean seedlings treated with ZnONPs and K+ in normal and As-polluted soil. As stress alleviation was credited to reduce As uptake in faba bean seedlings treated with synergistic application of ZnONPs and K+ . It is proposed that K+ interaction with nanoparticles can be exploited at molecular level to understand the mechanisms involved in abiotic stress tolerance.

BioClay nanosheets infused with GA3 ameliorate the combined stress of hexachlorobenzene and temperature extremes in Brassica alboglabra plants.

Environmental pollutants and climate change are the major cause of abiotic stresses. Hexachlorobenzene (HCB) is an airborne and aero-disseminated persistent organic pollutants (POP) molecule causing severe health issues in humans, and temperature extremes and HCB in combination severely affect the growth and yield of crop plants around the globe. The higher HCB uptake and accumulation by edible plants ultimately damage human health through the contaminated food chain. Hence, confining the passive absorbance of POPs is a big challenge for researchers to keep the plant products safer for human consumption. BioClay functional layered double hydroxide is an effective tool for the stable delivery of acidic molecules on plant surfaces. The current study utilized gibberellic acid (GA3) impregnated BioClay (BioClay GA ) to alleviate abiotic stress in Brassica alboglabra plants. Application of BioClay GA mitigated the deleterious effects of HCB besides extreme temperature stress in B. alboglabra plants. BioClay GA significantly restricted HCB uptake and accumulation in applied plants through increasing the avoidance efficacy (AE) up to 377.61%. Moreover, the exogenously applied GA3 and BioClay GA successfully improved the antioxidative system, physiochemical parameters and growth of stressed B. alboglabra plants. Consequently, the combined application of BioClay and GA3 can efficiently alleviate low-temperature stress, heat stress, and HCB toxicity.

Iron oxide nanoparticles and selenium supplementation improve growth and photosynthesis by modulating antioxidant system and gene expression of chlorophyll synthase (CHLG) and protochlorophyllide oxidoreductase (POR) in arsenic-stressed Cucumis melo.

Current research reveals the positive role of iron oxide nanoparticles (IONPs) and selenium (Se) in extenuation of arsenic (As) induced toxicity in Cucumis melo. C. melo plants grown in As spiked soil (20 mg kg-1 As) showed reduced growth, chlorophyll (Chl) content, photosynthetic rate, stomatal conductivity and transpiration. On the other hand, the alone applications of IONPs or Se improved growth and physiochemical parameters of C. melo plants. Additionally, exogenous application IONPs and Se synergistically improved the activity of antioxidative enzymes and glyoxalase system in C. melo plants. In addition, the collective treatment of IONPs and Se reduced As uptake, enhanced rate of photosynthesis and increased gas exchange attributes of C. melo plants under As stress. Interactive effect of IONPs and Se regulated reduced glutathione (GSH), oxidized glutathione (GSSG) and ascorbate (AsA) content in C. melo plants exposed to As-contaminated Soil. IONPs and Se treatment also regulated expression of respiratory burst oxidase homologue D (RBOHD) gene, chlorophyll synthase (CHLG) and protochlorophyllide oxidoreductase (POR). Therefore, the combined treatment of IONPs and Se may enhance the growth of crop plants by alleviating As stress.

Iron Oxide and Silicon Nanoparticles Modulate Mineral Nutrient Homeostasis and Metabolism in Cadmium-Stressed Phaseolus vulgaris.

The application of nanoparticles (NPs) has been proved as an efficient and promising technique for mitigating a wide range of stressors in plants. The present study elucidates the synergistic effect of iron oxide nanoparticles (IONPs) and silicon nanoparticles (SiNPs) in the attenuation of Cd toxicity in Phaseolus vulgaris. Seeds of P. vulgaris were treated with IONPs (10 mg/L) and SiNPs (20 mg/L). Seedlings of uniform size were transplanted to pots for 40 days. The results demonstrated that nanoparticles (NPs) enhanced growth, net photosynthetic rate, and gas exchange attributes in P. vulgaris plants grown in Cd-contaminated soil. Synergistic application of IONPs and SiNPs raised not only K+ content, but also biosynthesis of polyamines (PAs), which alleviated Cd stress in P. vulgaris seedlings. Additionally, NPs decreased malondialdehyde (MDA) content and electrolyte leakage (EL) in P. vulgaris plants exposed to Cd stress. These findings suggest that stress alleviation was mainly attributed to the enhanced accumulation of K+ content, improved antioxidant defense system, and higher spermidine (Spd) and putrescine (Put) levels. It is suggested that various forms of NPs can be applied synergistically to minimize heavy metal stress, thus increasing crop production under stressed conditions.

Calcium Nanoparticles Impregnated With Benzenedicarboxylic Acid: A New Approach to Alleviate Combined Stress of DDT and Cadmium in Brassica alboglabra by Modulating Bioacummulation, Antioxidative Machinery and Osmoregulators.

At present, the alleviation of stress caused by climate change and environmental contaminants is a crucial issue. Dichlorodiphenyltrichloroethane (DDT) is a persistent organic pollutant (POP) and an organochlorine, which causes significant health problems in humans. The stress caused by cadmium (Cd) and the toxicity of DDT have direct effects on the growth and yield of crop plants. Ultimately, the greater uptake and accumulation of DDT by edible plants affects human health by contaminating the food chain. The possible solution to this challenging situation is to limit the passive absorption of POPs into the plants. Calcium (Ca) is an essential life component mandatory for plant growth and survival. This study used impregnated Ca (BdCa) of benzenedicarboxylic acid (Bd) to relieve abiotic stress in plants of Brassica alboglabra. BdCa mitigated the deleterious effects of Cd and reduced DDT bioaccumulation. By increasing the removal efficacy (RE) up to 256.14%, BdCa greatly decreased pollutant uptake (Cd 82.37% and DDT 93.64%) and supported photosynthetic machinery (86.22%) and antioxidant enzyme defenses (264.73%), in applied plants. Exogenously applied Bd also successfully improved the antioxidant system and the physiochemical parameters of plants. However, impregnation with Ca further enhanced plant tolerance to stress. This novel study revealed that the combined application of Ca and Bd could effectively relieve individual and combined Cd stress and DDT toxicity in B. alboglabra.

Spermine-mediated polyamine metabolism enhances arsenic-stress tolerance in Phaseolus vulgaris by expression of zinc-finger proteins related genes and modulation of mineral nutrient homeostasis and antioxidative system.

The contamination of groundwater and agricultural land by metalloids especially arsenic (As) is one of the most serious threats to people and plants worldwide. Therefore, the present study was design to explore the role of spermine (Spm)- mediated polyamine metabolism in the alleviation of arsenic (As) toxicity in common bean (Phaseolus vulgaris L.). It was noted that As stress caused reduction in the intracellular CO2 concentration, stomatal conductivity and transpiration rate as compared to the control treatment and also impairedplant growth attributes and mineral nutrient homeostasis (sulfur, phosphorus, potassium and calcium). However, the exogenous application of Spm resulted in a considerable enhance in the content of glutathione and nitric oxide, and the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione-reductase (GR), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) in P. vulgaris seedlings grown As-contaminated soil. In addition, Spm application significantly improved the endogenous production of putrescine and spermidine accompanied along with reduction in malondialdehyde, electrolyte leakage, hydrogen peroxide, superoxide level besides enhanced methylglyoxal (MG) detoxification. Moreover, Spm treatment elevated the expression level of zinc-finger proteins related genes (PvC3H24, PvC3H25, PvC3H26 and PvC3H27) involved in abiotic stress response. The study concluded that Spm acted as an enhancing agent and improved tolerance to As-toxicity by upregulating the expression of zinc-finger proteins related genes, polyamine metabolism, Mg detoxification and antioxidant system in P. vulgaris.

Alleviation of cadmium phytotoxicity in triacontanol treated Coriandrum sativum L. by modulation of physiochemical attributes, oxidative stress biomarkers and antioxidative system.

Cadmium (Cd) is a hazardous metal that has a significant risk of transfer from soil to edible parts of food crops including shoots and seeds. Reduction of Cd accumulation is required to lower the risk of Cd exposure in humans and animals feeding on metal contaminated parts of such plants. Coriandrum sativum L. (coriander) exposed to Cd showed stress symptoms such as stunted growth, reduced photosynthetic activity and synthesis of chlorophyll pigments. Growth inhibition in Cd-treated plants was attributed to induction of oxidative stress as demonstrated by higher level of stress biomarkers such as electrolyte leakage, lipid peroxidation and hydrogen peroxide. Primary objective of the current study was to observe the ameliorative role of triacontanol (Tria) in Cd-stressed coriander seedlings. For this purpose, coriander seeds were primed with Tria concentrations of 5, 10, and 20 µmol L-1. Seedlings developed from Tria treated seeds exhibited reduced loss of photosynthetic pigments; mitigated oxidative stress caused by Cd, through improved efficacy of antioxidant machinery comprising superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT) enzymes besides non-enzymatic antioxidants including proline, phenolics and flavonoids. Triacontanol treated seedlings showed enhanced yield attributes suggesting that exogenous Tria could be employed to improve plant tolerance to Cd stress.

Selenium seed priming enhanced the growth of salt-stressed Brassica rapa L. through improving plant nutrition and the antioxidant system.

Various abiotic stresses may affect the germination, growth, and yield of direct-seeded vegetable crops. Seed priming with effective antioxidant mediators may alleviate these environmental stresses by maintaining uniformity in seed germination and improving the subsequent health of developing seedlings. Salt-induced stress has become a limiting factor for the successful cultivation of Brassica rapa L., especially in Southeast Asian countries. The present study was performed to elucidate the efficacy of seed priming using selenium (Se) in mitigating salt-induced oxidative stress in turnip crops by reducing the uptake of Na+. In this study, we administered three different levels of Se (Se-1, 75 µmol L-1; Se-2, 100 µmol L-1; and Se-3, 125 µmol L-1) alone or in combination with NaCl (200 mM). Conspicuously, salinity and Se-2 modulated the expression levels of the antioxidant genes, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX). The upregulated expression of stress-responsive genes alleviated salt stress by scavenging the higher reactive oxygen species (ROS) level. The stress ameliorative potential of Se (Se-2 = 100 µmol L-1) enhanced the final seed germination percentage, photosynthetic content, and seedling biomass production up to 48%, 56%, and 51%, respectively, under stress. The advantageous effects of Se were attributed to the alleviation of salinity stress through the reduction of the levels of malondialdehyde (MDA), proline, and H2O2. Generally, treatment with Se-2 (100 µmo L-1) was more effective in enhancing the growth attributes of B. rapa compared to Se-1 (75 µmo L-1) and Se-3 (125 µmo L-1) under salt-stressed and non-stressed conditions. The findings of the current study advocate the application of the Se seed priming technique as an economical and eco-friendly approach for salt stress mitigation in crops grown under saline conditions.

Titanium dioxide nanoparticles mitigate cadmium toxicity in Coriandrum sativum L. through modulating antioxidant system, stress markers and reducing cadmium uptake.

Anthropogenic activities are the foremost reason of metal pollution in soils of the cultivated areas, resulting abnormal physiochemical processes in plants. Among metals contaminants, cadmium (Cd) is one of the most injurious contaminants that deleteriously affect physiological activities, growth and yield of the crop plants. Keeping in view the stress mitigation potential of titanium dioxide (TiO2), the existing research work was premeditated to inspect the beneficial role of seed priming with titanium dioxide nanoparticles (TiO2-NPs) on biochemical, morphological and physiological characteristics of Coriandrum sativum L. (coriander) plants under Cd stress. For this purpose, C. sativum seeds were primed with 0, 40, 80 and 160 mg L-1 TiO2-NPs. Cadmium stress triggered a significant decrease in chlorophyll a content (49%), chlorophyll b content (44%), photosynthetic rate (62%) and plant growth (51%) as compared with control. Tanium dioxide nanoparticles treated seedlings exhibited reduced Cd contents besides improved agronomic traits (seedlings biomass, number of seeds and yield). The TiO2-NPs treatment declined the magnitude of EL and MDA by 1.5 fold and 1.71 fold, respectively. Furthermore, TiO2-NPs diminished oxidative injuries in plants exposed to Cd stress. Additionally, TiO2-NPs enhanced the biosynthesis of osmatic regulators (proline) by 47% which helped in the mitigation of Cd persuaded toxicity in plants. Briefly, treatment of 80 mg L-1 TiO2-NPs perhaps ameliorates the deleterious influence of Cd stress and enhance the yield of coriander.

Synergistic application of silver nanoparticles and indole acetic acid alleviate cadmium induced stress and improve growth of Daucus carota L.

Cadmium (Cd) is one of the major hazardous elements that is very toxic to the health of both human and plants. The toxicity of Cd causes plants to suffer by disabling their overall physiological mechanisms. Therefore, present study was intended to investigate the synergistic role of AgNPs and IAA in improving the resilience against Cd toxicity and underlaying physiological and biochemical mechanisms in carrot (Daucus carota L.) plants. Also, the existence of genotypic variation for Cd tolerance in D. carota was also studied. The results revealed that Cd stress decreased plant growth attributes like root diameter, root length, root weight, shoot weight, shoot length, leaves fresh weight and leaves dry weight. Nonetheless, AgNPs and IAA mitigated Cd stress by detoxifying reactive oxygen species (ROS). Additionally, the application of AgNPs and IAA boosted plant growth through reducing the level of malondialdehyde (MDA). Enhancement in the activity of phenol synthesizing and oxidizing enzymes including peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase was also observed by application of AgNPs and IAA. The increased activities of antioxidant enzymes including POX, PPO and PAL by the combined application of AgNPs and IAA advocate stress ameliorative role against Cd stress in plants. The enhanced Cd content was detected in the roots as compared to shoots of treated plants. Pre breed 22 was found as a Cd tolerant genotype.

Role of magnesium oxide nanoparticles in the mitigation of lead-induced stress in Daucus carota: modulation in polyamines and antioxidant enzymes.

During the current study, the effects of magnesium oxide nanoparticles (5 mmol/L) were observed on the growth and mineral nutrients of Daucus carota under lead (Pb) stress. The results demonstrated that Pb stress decreased the growth and photosynthetic rate of D. carota plants. Furthermore, Pb stressed plants showed decreased uptake of mineral nutrients including Zn, Na, Fe, K, Ca, Mg, K, and Cu. Similarly, Pb stressed plants showed enhanced electrolyte leakage (EL) and malondialdehyde (MDA) content. However, magnesium oxide nanoparticles detoxified ROS to mitigate Pb stress and improved the growth of plants. Magnesium oxide nanoparticles also escalated the activity of antioxidant enzymes including superoxide dismutase (SOD) and Catalase (CAT). A higher amount of Pb content was observed in the roots as compared to the shoot of plants. Lead toxicity reduced manganese accumulation in D. carota plants. The increased concentration of iron, manganese, copper, and zinc advocates stress the ameliorative role of Pb stress in plants. Novelty statementThe role of MgONPs in the alleviation of Pb-toxicity in Daucus carota has never been exploited. In addition, the potential of MgONPs to enhance nutritional content in D. carota via modulation in antioxidant system and polyamines have never been reported.

Role of exogenously applied putrescine in amelioration of cadmium stress in Coriandrum sativum by modulating antioxidant system.

Abiotic stress reduces the plant growth and biomass production. Putrescine (Put) may be applied to alleviate numerous types of abiotic stresses in plants. The present research was intended to evaluate the role of exogenously applied Put in extenuation of cadmium (Cd) stress in coriander plants. Coriander seeds primed with 0.25, 0.5, and1 mM Put were allowed to grow in 50 mg kg-1 Cd contaminated soil for one month. Put treatment improved seed germination, gas exchange attributes, root growth and shoot growth of coriander. The improved activity of stress-responsive enzymes such as superoxide dismutase, catalase and peroxidase, besides amplification of proline was observed in Put treated seedlings under Cd stress. In addition, a reduced amount of total soluble protein and sugars content were noticed in Cd stressed seedlings. Nevertheless, Put reduced MDA level in treated plants. Our results demonstrated that Put mitigated Cd induced stress by modulating antioxidants and photosynthetic activity of coriander plants.Novelty statement Most of the researchers have studied the role of endogenous putrescine in alleviation of plant stress. However, during current study, we primed coriander seeds with putrescine. Our results elucidated very promising role of exogenously applied putrescine in stress mitigation and growth improvement of coriander seedlings under Cd stress. The findings of current study advocate the application of putrescine for stress alleviation in crop plants.

Selenium nanoparticles reduced cadmium uptake, regulated nutritional homeostasis and antioxidative system in Coriandrum sativum grown in cadmium toxic conditions.

Nanotechnology has become a valuable novel approach to manage several environmental challenges through providing innovative and effective solutions. Heavy metal stress is an important abiotic limiting factor. Seed priming with selenium (Se) alleviates various kinds of environmental stresses; yet, the potential of seed priming with selenium nanoparticles (SeNPs) under cadmium (Cd) stress for coriander crop has never been evaluated. This research work was designed to explore the effects of seed priming with three levels (0, 5, 10 and 15 mg L-1) of SeNPs solution on the physio-biochemical characteristics, nutrition, antioxidative defense system and growth of coriander under Cd stress. Cadmium toxicity reduced chlorophyll content, photosynthetic activity and growth of treated plants. Moreover, Cd stressed plants exhibited modulations in proline level, together with decreased water potential, and leaf osmotic potential. However, SeNPs increased growth attributes, chlorophyll content, total soluble sugars, leaf relative water content, and gas exchange parameters in treated plants which were conversely decreased by Cd toxicity. The seeds priming with SeNPs promoted antioxidant response by increasing catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX) activity and safeguarding cellular structures through scavenging free radicals and reactive oxygen species. Furthermore, Cd stressed plants displayed an upper level of MDA (1.91 fold) while SeNPs improved membranous integrity through detoxification of hydrogen peroxide. Additionally, SeNPs enhanced nutrients contents (P, K, Ca, Mg, Zn), metal tolerance index and diminished Cd content in plants resulting in the improved growth and development of Cd affected coriander plants.