Application Of Nitric Oxide Donor Research Articles

Extracellular nitric oxide sustains root surface redox activity and growth under sudden flooding-induced hypoxic conditions in barley root tips

Main conclusionNitric oxide sustains root tip surface redox activity and restricts lipid peroxidation-triggered cell death in the root tips.In order to gain more insight into the involvement of nitric oxide (NO) in plant response to sudden flooding-induced hypoxic stress, we studied the effect of two NO donors, sodium nitroprusside and S-nitroso-L-glutathione, on short-term partial submergence-induced root growth inhibition, alteration in root surface redox activity, lipid peroxidation and cell death in two barley cultivars (cv.) at their early seedling stage. The short-term hypoxic stress induces root growth arrest in cv. Karmel, accompanied by increased lipid peroxidation and cell death. By contrast, in cv. Slaven, short-term hypoxic conditions cause only reduced root growth rate, associated with elevated extracellular NO level in the root tips. The root tip surface redox activity decreases with the increasing timespan of hypoxic conditions in both cultivars; however, this decrease in redox activity started earlier and was greater in the cv. Karmel in comparison with cv. Slaven. Application of NO donors during hypoxic stress sustains the root redox activity and eliminates the hypoxia-induced lipid peroxidation, accompanied by a partial restoration of root growth after short-term hypoxic stress. These results suggest that extracellular NO plays a key role in maintaining the root tip surface redox activity and in the restriction of lipid peroxidation and cell death under short-term hypoxic stress in the root tips of barley seedlings.

Progress in the Application of Nitric Oxide Donors to Promote Cervical Ripening

Progress in the Application of Nitric Oxide Donors to Promote Cervical Ripening

Heavy metal toxicity in plants and the potential NO-releasing novel techniques as the impending mitigation alternatives.

Environmental pollutants like heavy metals are toxic, persistent, and bioaccumulative in nature. Contamination of agricultural fields with heavy metals not only hampers the quality and yield of crops but also poses a serious threat to human health by entering the food chain. Plants generally cope with heavy metal stress by regulating their redox machinery. In this context, nitric oxide (NO) plays a potent role in combating heavy metal toxicity in plants. Studies have shown that the exogenous application of NO donors protects plants against the deleterious effects of heavy metals by enhancing their antioxidative defense system. Most of the studies have used sodium nitroprusside (SNP) as a NO donor for combating heavy metal stress despite the associated concerns related to cyanide release. Recently, NO-releasing nanoparticles have been tested for their efficacy in a few plants and other biomedical research applications suggesting their use as an alternative to chemical NO donors with the advantage of safe, slow and prolonged release of NO. This suggests that they may also serve as potential candidates in mitigating heavy metal stress in plants. Therefore, this review presents the role of NO, the application of chemical NO donors, potential advantages of NO-releasing nanoparticles, and other NO-release strategies in biomedical research that may be useful in mitigating heavy metal stress in plants.

ELO2 Participates in the Regulation of Osmotic Stress Response by Modulating Nitric Oxide Accumulation in Arabidopsis.

The ELO family is involved in synthesizing very-long-chain fatty acids (VLCFAs) and VLCFAs play a crucial role in plant development, protein transport, and disease resistance, but the physiological function of the plant ELO family is largely unknown. Further, while nitric oxide synthase (NOS)-like activity acts in various plant environmental responses by modulating nitric oxide (NO) accumulation, how the NOS-like activity is regulated in such different stress responses remains misty. Here, we report that the yeast mutant Δelo3 is defective in H2O2-triggered cell apoptosis with decreased NOS-like activity and NO accumulation, while its Arabidopsis homologous gene ELO2 (ELO HOMOLOG 2) could complement such defects in Δelo3. The expression of this gene is enhanced and required in plant osmotic stress response because the T-DNA insertion mutant elo2 is more sensitive to the stress than wild-type plants, and ELO2 expression could rescue the sensitivity phenotype of elo2. In addition, osmotic stress-promoted NOS-like activity and NO accumulation are significantly repressed in elo2, while exogenous application of NO donors can rescue this sensitivity of elo2 in terms of germination rate, fresh weight, chlorophyll content, and ion leakage. Furthermore, stress-responsive gene expression, proline accumulation, and catalase activity are also repressed in elo2 compared with the wild type under osmotic stress. In conclusion, our study identifies ELO2 as a pivotal factor involved in plant osmotic stress response and reveals its role in regulating NOS-like activity and NO accumulation.

Endogenous nitric oxide contributes to chloride and sulphate salinity tolerance by modulation of ion transporter expression and reestablishment of redox balance in Brassica napus cultivars

Salinity is an adverse environmental stress for crop plants and the mechanism of salinity tolerance and its interaction with phytohormone like nitric oxide (NO) is still lacking, especially for Na2SO4 in B. napus. Therefore, in the present study, B. napus cultivars were grown under equimolar concentrations of NaCl/Na2SO4 and with their anions (KCl/K2SO4), to discriminate toxic responses of different types of salts on growth, oxidative stress, antioxidant defense, anion concentration and endogenous production of NO. Results showed that plant growth, photosynthetic rate and pigments productions were strongly inhibited under Na+ dominated salt treatments (NaCl/Na2SO4). As a result, production of oxidative stress (H2O2, O2.-, MDA, EL) related parameters were significantly induced under these treatments. The uptake of Na+ was high in B. napus cultivars irrespective of chloride/sulphate anions presence. However, Cl- and SO42- anions accumulation was only high in sensitive cultivars. The differential responses of B. napus cultivars against salinity treatments were associated with endogenous production of NO. The tolerant cultivar maintained higher level of NO, while sensitive cultivars experience a reduction in NO and inhibition of its biosynthesis enzymes, upon exposure to salinity treatments. To prove NO involvement, NO scavenger was applied on the leaves of B. napus cultivars, which significantly induced salt toxicity symptoms, oxidative stress and upregulated gene expression of ion transporters and uptake of Na+, Cl- and SO42-. Conversely, application of NO donor (sodium nitroprusside) reversed the salinity induce oxidative stress, ion accumulation and stimulated antioxidant defense in B. napus cultivars. Thus, the present study shows that endogenous NO level could act as an essential signaling molecule for triggering and activating the salinity adaptive response in rapeseed and Na+ toxicity plays a dominate role in growth inhibition, while the additive effect of chloride/sulphate anions may be cultivar dependent.

Nitric oxide alleviates salt-induced stress damage by regulating the ascorbate–glutathione cycle and Na+/K+ homeostasis in Nitraria tangutorum Bobr

Nitric oxide (NO) is an important signaling molecule involved in mediation of salt stress induced physiological responses in plants. In this study, we investigated the effect of NO on Nitraria tangutorum seedlings exposed to salt stress. Exogenous application of NO donor, sodium nitroprusside (SNP) increased fresh weight, shoot and root elongation and decreased electrolyte leakage and malondialdehyde (MDA) content in N. tangutorum seedlings under salt stress. Simultaneously, leaf senescence and root damage induced by salt stress were alleviated. SNP effectively increased NO content both in leaves and roots of plants under salt stress. Meanwhile, SNP activated the ascorbate-glutathione (AsA-GSH) cycle by increasing antioxidants contents, antioxidant enzymes activities, and related genes expression, thereby scavenging reactive oxygen species (ROS) and alleviating oxidative damage caused by salt stress. SNP alleviated salt stress induced ion toxicity by promoting Na+ efflux and ion transporter gene expression and reducing Na+ content and the Na+/K+ ratio. In addition, application of NO specific scavenger cPTIO and mammalian NO synthase inhibitor L-NAME sifnificantly aggravated stress damage in plant under salt stress. These results show the beneficial impacts of NO as a stress-signaling molecule that positively regulates defense response in N. tangutorum to salt stress.

Involvement of nitric oxide (NO) in plant responses to metalloids

Plants respond to the limited or excess supply of metalloids, boron (B), silicon (Si), selenium (Se), arsenic (As), and antimony (Sb) via complex signaling pathways that are mainly regulated by nitric oxide (NO). The absorption of metalloids from the soil is facilitated by pathways that involve aquaporins, aquaglyceroporins, phosphate, and sulfate transporters; however, their regulation by NO is poorly understood. Using in silico software, we predicted the S-nitrosation of known metalloid transporters, proposing NO-dependent regulation of metalloid transport systems at the posttranslational level. NO intensifies the stress-mitigating effect of Si, whereas in the case of Se, As, and Sb, the accumulation of NO or reactive nitrogen species contributes to toxicity. NO promotes the beneficial effect of low Se concentrations and mitigates the damage caused by B deficiency. In addition, the exogenous application of NO donor, sodium nitroprusside, reduces B, Se, and As toxicity. The primary role of NO in metalloid stress response is to mitigate oxidative stress by activating antioxidant defense at the level of protein activity and gene expression. This review discusses the role of NO in plant responses to metalloids and suggests future research directions.

Alterations in antioxidative machinery and growth parameters upon application of nitric oxide donor that reduces detrimental effects of cadmium in rice seedlings with increasing days of growth

Finding its way into the agricultural lands through various sources Cadmium (Cd) has been proved to be deleterious in plant systems. Cd-induced oxidative stress tampers with both plant's physiology and biochemistry. Nitric oxide (NO) is a key signaling molecule in plant stress response and plays a significant role in many regulatory pathways of plant development. This study investigates the effect on rice seedlings grown under 50 µM Cd/SNP alone or in combination in the growth medium, on roots and shoots of rice cv. HUR 3022 at 1, 4, and 7 days of growth. Plants treated with Cd alone showed diminished growth, decreased length and weight, lower cell viability and less chlorophyll. Application of equimolar quantity of SNP to cadmium-stressed rice within the growth medium repressed Cd-uptake and reversed the Cd-induced detrimental effects. Rice plants treated with only Cd showed high oxidative stress. Specific activity of antioxidant enzymes such as guaiacol peroxidase, ascorbate peroxidase and glutathione reductase were increased. Antioxidants like glutathione and ascorbate had lower levels in cadmium treated plants. A high amount of reactive oxygen species were generated in cadmium treated plants which were supported by the histochemical studies for - hydrogen peroxide and superoxide anion. Application of SNP in rice plants under cadmium-stress in the growth medium mitigated the Cd-induced oxidative stress by elevating the levels of antioxidants and reducing the amount of reactive oxygen species produced. These results were supported by reduced specific activity of oxidative enzymes. The results indicate that NO when supplemented exogenously, diminishes the deleterious effects of Cd in rice plants. Our study presents report from the early days of plant development i.e., 1,4,7 days of growth because physiological and biochemical changes occurring during these early developmental days may provide significant insights into rice plant's adaptation strategy towards any perceived stress.

Exogenous application of nitric oxide donors regulates short-term flooding stress in soybean.

Short-term water submergence to soybean (Glycine max L.) create hypoxic conditions hindering plant growth and productivity. Nitric oxide (NO) is considered a stress-signalling and stress-evading molecule, however, little is known about its role during flooding stress. We elucidated the role of sodium nitroprusside (SNP) and S-nitroso L-cysteine (CySNO) as NO donor in modulation of flooding stress-related bio-chemicals and genetic determinants of associated nitrosative stress to Daewon and Pungsannamul soybean cultivars after 3 h and 6 h of flooding stress. The results showed that exogenous SNP and CysNO induced glutathione activity and reduced the resulting superoxide anion contents during short-term flooding in Pungsannamul soybean. The exo- SNP and CysNO triggered the endogenous S-nitrosothiols, and resulted in elevated abscisic acid (ABA) contents in both soybean cultivars overtime. To know the role of ABA and NO related genes in short-term flooding stress, the mRNA expression of S-nitrosoglutathione reductase (GSNOR1), NO overproducer1 (NOX1) and nitrate reductase (NR), Timing of CAB expression1 (TOC1), and ABA-receptor (ABAR) were assessed. The transcripts accumulation of GSNOR1, NOX1, and NR being responsible for NO homeostasis, were significantly high in response to early or later phases of flooding stress. ABAR and TOC1 showed a decrease in transcript accumulation in both soybean plants treated with exogenous SNP and CySNO. The exo- SNP and CySNO could impinge a variety of biochemical and transcriptional programs that can mitigate the negative effects of short-term flooding stress in soybean.

Nitric oxide and light co-regulate glycine betaine homeostasis in sunflower seedling cotyledons by modulating betaine aldehyde dehydrogenase transcript levels and activity

ABSTRACTGlycine betaine (GB), an osmolyte, is produced in chloroplasts by the action of betaine aldehyde dehydrogenase (BADH) on its precursor betaine aldehyde. The present work highlights the significance of nitric oxide (NO) in GB homeostasis as a long-distance salt (120 mM NaCl) stress-elicited response. In light-grown seedling cotyledons, both the activity and transcript levels of BADH are much higher than in dark-grown seedlings irrespective of salt stress. Significantly high accumulation of GB in dark-grown seedling cotyledons indicates its preferential mobilization from cotyledons to other plant parts in light-grown seedlings. NO donor application (diethylenetriamine) maintains high BADH activity in light, although in dark it is brought down marginally. BADH levels are maintained high in light than in dark in respective treatments. Reversal of the effect of NO donor on age-dependent GB content, BADH activity, and transcript levels by NO scavenger (diethyldithiocarbamate) further demonstrates the impact of NO on GB homeostasis in light- and dark-grown seedlings in an age-dependent manner, major modulation being observed in 4-d-old seedlings. The present work, thus, provides new information on co-regulation of GB homeostasis by NO and light. It also puts forward new information of GB–NO crosstalk in maneuvering salt stress sensing as a long-distance response in seedlings.

Nitric oxide as a messenger between neurons and satellite glial cells in dorsal root ganglia

Abnormal neuronal activity in sensory ganglia contributes to chronic pain. There is evidence that signals can spread between cells in these ganglia, which may contribute to this activity. Satellite glial cells (SGCs) in sensory ganglia undergo activation following peripheral injury and participate in cellular communication via gap junctions and chemical signaling. Nitric oxide (NO) is released from neurons in dorsal root ganglia (DRG) and induces cyclic GMP (cGMP) production in SCGs, but its role in SGC activation and neuronal excitability has not been explored. It was previously reported that induction of intestinal inflammation with dinitrobenzoate sulfonate (DNBS) increased gap junctional communications among SGCs, which contributed to neuronal excitability and pain. Here we show that DNBS induced SGC activation in mouse DRG, as assayed by glial fibrillary acidic protein upregulation. DNBS also upregulated cGMP level in SGCs, consistent with NO production. In vitro studies on intact ganglia from DNBS-treated mice showed that blocking NO synthesis inhibited both SGCs activation and cGMP upregulation, indicating an ongoing NO production. Application of NO donor in vitro induced SGC activation, augmented gap junctional communications, and raised neuronal excitability, as assessed by electrical recordings. The cGMP analog 8-Br-cGMP mimicked these actions, confirming the role of the NO-cGMP pathway in intraganglionic communications. NO also augmented Ca2+ waves propagation in DRG cultures. It is proposed that NO synthesis in DRG neurons increases after peripheral inflammation and that NO induces SGC activation, which in turn contributes to neuronal hyperexcitability. Thus, NO plays a major role in neuron-SGC communication.

Nitric oxide regulates plant responses to drought, salinity, and heavy metal stress

Plants are exposed to diverse abiotic stresses like drought, heat, salinity, and high-metal concentrations at different stages of their life cycle. As protection against stress, plants release signaling molecules that initiate a cascade of stress-adaptation responses leading either to programmed cell death or plant acclimation. Nitric oxide (NO) is a small but important redox signaling molecule that in plants is involved in a diverse range of physiological processes including germination, development, flowering, senescence, and abiotic stress. Although the exact role of NO in plants remains unclear and is species dependent, various studies have suggested a positive correlation between NO accumulations in stress in plants. In this article, we review and discuss the biosynthesis of NO, sources and exogenous application of NO donors under drought, salt, and heavy metal stress. A review of publications indicated that, in general, application of exogenous NO alleviates the negative stress effects in plants and improves antioxidant activity in most plant species. In addition, S-nitrosylation and tyrosine nitration are two NO-mediated posttranslational modification. All these factors are important in protecting plants from diverse stresses and vary with the species. Furthermore, to determine precise mechanisms of action of NO is expected to help in efficient utilization of crop cultivation under stress conditions.

Nitric oxide mediates aluminum-induced citrate secretion through regulating the metabolism and transport of citrate in soybean roots

Citrate secretion is a kind of typical strategy for plant against aluminum (Al) toxicity. However, the signaling process in Al-activated citrate secretion needs to be clarified. Physiological and biochemical methods as well as gene expression analysis were employed to examine the regulatory roles of nitric oxide (NO) in Al-activated citrate secretion in soybean roots. Application of NO donor alleviated root growth inhibition and decreased Al content in Al-treated root apices. Al-induced NO production and citrate secretion were further elevated by NO donor, but inhibited by NO scavenger. Inhibition of citrate synthase (CS) or plasma membrane (PM) H+-ATPase activity significantly decreased Al-induced secretion of citrate, but inhibition of aconitase (ACO) activity enhanced citrate secretion under Al stress. Furthermore, NO mediated Al-stimulated CS and PM H+-ATPase activities, but decreased ACO activity under Al stress. Further investigation showed that NO modulated Al-activated transcriptional expression of CS and PM H+-ATPase as well as GmMATE. Overexpression of GmMATE in soybean hairy roots caused an enhanced Al-induced citrate efflux and Al resistance. Our findings suggest that NO-dependent up-regulation of citrate synthesis and activation of PM H+-ATPase-coupled MATE transporter co-transport system participates in Al-activated citrate exudation, thus conferring plant resistance to Al toxicity.

Hypothalamic paraventricular nucleus neuronal nitric oxide synthase activity is a major determinant of renal sympathetic discharge in conscious Wistar rats.

What is the central question of this study? Does chronic reduction of neuronally generated nitric oxide in the hypothalamic paraventricular nucleus affect the set-point regulation of blood pressure and sympathetic activity destined to the kidneys? What is the main finding and its importance? Within the hypothalamic paraventricular nucleus, nitric oxide generated by neuronal nitric oxide synthase plays a major constitutive role in suppressing long term the levels of both ongoing renal sympathetic activity and arterial pressure in conscious Wistar rats. This finding unequivocally demonstrates a mechanism by which the diencephalon exerts a tonic influence on sympathetic discharge to the kidney and may provide the basis for both blood volume and osmolality homeostasis. The paraventricular nucleus (PVN) of the hypothalamus plays a crucial role in cardiovascular and neuroendocrine regulation. Application of nitric oxide donors to the PVN stimulates GABAergic transmission, and may suppress sympathetic nerve activity (SNA) to lower arterial pressure. However, the role of endogenous nitric oxide within the PVN in regulating renal SNA chronically remains to be established in conscious animals. To address this, we used our previously established lentiviral vectors to knock down neuronal nitric oxide synthase (nNOS) selectively in the PVN of conscious Wistar rats. Blood pressure and renal SNA were monitored simultaneously and continuously for 21days (n=14) using radio-telemetry. Renal SNA was normalized to maximal evoked discharge and expressed as a percentage change from baseline. The PVN was microinjected bilaterally with a neurone-specific tetracycline-controllable lentiviral vector, expressing a short hairpin miRNA30 interference system targeting nNOS (n=7) or expressing a mis-sense as control (n=7). Recordings continued for a further 18days. The vectors also expressed green fluorescent protein, and successful expression in the PVN and nNOS knockdown were confirmed histologically post hoc. Knockdown of nNOS expression in the PVN resulted in a sustained increase in blood pressure (from 95±2 to 104±3mmHg, P<0.05), with robust concurrent sustained activation of renal SNA (>70%, P<0.05). The study reveals a major role for nNOS-derived nitric oxide within the PVN in chronic set-point regulation of cardiovascular autonomic activity in the conscious, normotensive rat.

Nitric oxide production shifts metabolic pathways toward lignification to alleviate Pb stress in Prosopis farcta

The mechanisms through which nitric oxide (NO) can influence plant tolerance to Pb are unknown, but may be based on the accumulation of secondary metabolites such as phenolic compounds and polyamines (PAs). This hypothesis was tested by exposing hydroponically-cultured Prosopis farcta to Pb alone and in combination with sodium nitroprusside (SNP; NO donor), L-NAME (NO synthase inhibitor) and tungstate (TUN; nitrate reductase inhibitor) for a time course of 72h. The inhibitors strongly repressed NO generation, verifying that Pb and Pb+SNP-induced NO is probably mediated by nitrite and arginine-dependent pathways. The results show that the Pb-induced inhibition of growth was alleviated through application of NO donor, which decreased Pb accumulation in the plant samples, but deteriorated with the decrease in NO, which indicates a higher level of Pb absorbed.The elevated contents of phenolic acids under Pb and Pb+SNP treatments was reduced by the NOS and NR inhibitors and was significantly associated with phenylalanine ammonia-lyase (PAL) gene expression patterns. The arginine decarboxylase (ADC) gene in the PAs biosynthesis pathway remained unchanged. Considerable alteration was observed in the conjugated PAs in response to the Pb and Pb+SNP applications when compared with the NR and NOS inhibitors that exhibited an increase in free PAs. The results suggest that Pb-evoked NO promotes homeostasis of metabolic pathways to phenolic acids and conjugated PAs that enhance lignification to strengthen P. farcta against stress.

Exogenous application of nitric oxide modulates osmolyte metabolism, antioxidants, enzymes of ascorbate-glutathione cycle and promotes growth under cadmium stress in tomato.

Experiments were carried out to investigate the role of nitric oxide (NO) in ameliorating the negative effects of cadmium stress in tomato seedlings. Plants treated with cadmium (CdCl2, 150μM) showed reduced growth, biomass yield, pigment content, chlorophyll fluorescence, and gas exchange parameters. Exogenous application of NO donor (sodium nitroprusside) with nutrient solution protected chlorophyll pigments, restored chlorophyll fluorescence and gas exchange parameters, and caused significant enhancements in growth and biomass yield. Cadmium triggered the synthesis of proline and glycine betaine; however, application of NO caused further enhancement of their accumulation, reflecting an obvious amelioration of the cadmium-induced decline in relative water content. Activities of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase, monodehydroascorbate reductase, dehydroascorbate reductase, and other enzymatic activities of ascorbate-glutathione cycle were enhanced following the application of NO, as compared with those in untreated seedlings under control and cadmium stress conditions. NO increased the flavonoid and total phenol content in Cd-stressed tomato plants. Moreover, NO application restricted the uptake of cadmium and enhanced the accumulation of nutrients in different parts of tomato plants. On the basis of the findings of the present study, we propose that NO has a potential role as a growth promoter for tomato under cadmium stress.

“NO way”! Says the plant to abiotic stress

Nitric oxide (NO), a small sized, short lived, highly diffusible natured, gaseous, diatomic and bioactive molecule, has now gained an important position in plant science research, due to its multifunctional roles in physiological as well as pathological responses in plants. A detailed understanding of the molecular mechanisms of plants against various stresses revealed that production of NO and other reactive oxygen species (ROS) are known to interplay an essential role to counter those challenges. NO can directly or indirectly help in the modulation of different protein functions and the reprogramming of defense gene expression by interacting with certain targets. NO might act as a signal in activating ROS-scavenging enzyme activities under various abiotic stresses including drought, salinity, temperature, heavy metal and radiations stress. Furthermore, application of NO donor has tremendous potential to counteract damages in different segments of plants caused by various stresses. This review aims to discuss the overall role of NO in higher plants in response to abiotic stresses.

The Dynamics of the Defense Strategy of Pea Induced by Exogenous Nitric Oxide in Response to Aphid Infestation.

The aim of this study was to investigate the effect of exogenous nitric oxide (NO), i.e., S-nitrosoglutathione (GSNO) and sodium nitroprusside (SNP), on the metabolic status of Pisum sativum L. cv. Cysterski leaves infested by Acyrthosiphon pisum Harris, population demographic parameters and A. pisum feeding activity. A reduction in the level of semiquinone radicals in pea seedling leaves pretreated with exogenous NO occurred 24 h after A. pisum infestation, which was earlier than in non-pretreated leaves. A decrease in the level of O2•− was observed in leaves pretreated with GSNO and infested by aphids at 48 and 72 h post-infestation (hpi). Directly after the pretreatment with GSNO, an increase in the level of metal ions was recorded. NO considerably induced the relative mRNA levels for phenylalanine ammonia-lyase in 24-h leaves pretreated with NO donors, both non-infested and infested. NO stimulated the accumulation of pisatin in leaves until 24 h. The Electrical Penetration Graph revealed a reduction in the feeding activity of the pea aphid on leaves pretreated with NO. The present study showed that foliar application of NO donors induced sequentially defense reactions of pea against A. pisum and had a deterrent effect on aphid feeding and limited the population growth rate.

Potential use and perspectives of nitric oxide donors in agriculture.

Nitric oxide (NO) has emerged in the last 30 years as a key molecule involved in many physiological processes in plants, animals and bacteria. Current research has shown that NO can be delivered via donor molecules. In such cases, the NO release rate is dependent on the chemical structure of the donor itself and on the chemical environment. Despite NO's powerful signaling effect in plants and animals, the application of NO donors in agriculture is currently not implemented and research remains mainly at the experimental level. Technological development in the field of NO donors is rapidly expanding in scope to include controlling seed germination, plant development, ripening and increasing shelf-life of produce. Potential applications in animal production have also been identified. This concise review focuses on the use of donors that have shown potential biotechnological applications in agriculture. Insights are provided into (i) the role of donors in plant production, (ii) the potential use of donors in animal production and (iii) future approaches to explore the use and applications of donors for the benefit of agriculture. © 2016 Society of Chemical Industry.

Nitric oxide-releasing chitosan nanoparticles alleviate the effects of salt stress in maize plants

Nitric oxide (NO) is a signaling molecule involved in plant response to various abiotic stresses. However, the application of NO donors in agriculture is hampered by the instability of these compounds. Despite the successful uses of NO-releasing nanoparticles for biomedical purposes and the variety of nanomaterials developed as carrier systems of agrochemicals, the potential applications of nanocarriers for NO delivery in plants have not yet been tested. Herein, we report the synthesis and characterization of chitosan nanoparticles (CS NPs) containing the NO donor S-nitroso-mercaptosuccinic acid (S-nitroso-MSA). The efficiency of these NO-releasing NPs in mitigating the deleterious effects of salinity on maize plants was compared to that of the non-encapsulated NO donor. The NPs were synthesized through ionotropic gelation process, and mercaptosuccinic acid (MSA), the NO donor precursor, was encapsulated into CS NPs (91.07% encapsulation efficiency). Free thiol groups of MSA-CS NPs were nitrosated, leading to S-nitroso-MSA-CS NPs (NO-releasing NPs). The incorporation of S-nitroso-MSA into CS NPs allowed a sustained NO release. Treatments of salt-stressed maize plants with S-nitroso-MSA-CS NPs resulted in a higher leaf S-nitrosothiols content compared to that of free S-nitroso-MSA. Moreover, S-nitroso-MSA-CS NPs were more efficient than was the free NO donor in the amelioration of the deleterious effects of salinity in photosystem II activity, chlorophyll content and growth of maize plants because the protective action of the nanoencapsulated S-nitroso-MSA was achieved at lower dosages. Overall, these results demonstrate the positive impact of S-nitroso-MSA nanoencapsulation in increasing NO bioactivity in maize plants under salt stress.