Action Of Salicylic Acid Research Articles

Salicylic acid alleviates cadmium-induced stress responses through the inhibition of Cd-induced auxin-mediated reactive oxygen species production in barley root tips

Auxin is a master regulator of root growth by modulating its development under the constantly changing environment. Recently, an antagonistic interaction was suggested between SA and IAA signaling. Therefore, the purpose of this work was to analyze and compare the effect of the indole-3-acetic acid (IAA) signaling inhibitor p-chlorophenoxyisobutyric acid (PCIB) and salicylic acid (SA) as a potential IAA signaling inhibitor on the root growth, enzyme activity and reactive oxygen species (ROS) production in Cd- and IAA-treated barley root tips. Exposure of plants to Cd resulted in a more than threefold increase of IAA content in the root apex even 3h after the treatment. In addition, exogenously applied IAA evoked root responses such as root growth inhibition and swelling, ROS generation and activation of lipoxygenase or glutathione peroxidase identical to those induced by Cd. Furthermore, both Cd- and IAA-induced stress responses were markedly reversed by PCIB or SA post-treatment. Similarly to PCIB, SA did not affect the IAA content of root tips, suggesting the action of SA on the IAA signaling pathway in barley roots. SA probably does not alleviate the Cd toxicity in roots, but rather prevents or partially inhibits the root defense response to the presence of Cd through the inhibition of Cd-induced IAA-mediated ROS generation in roots.

Salicylic acid signaling inhibits apoplastic reactive oxygen species signaling.

BackgroundReactive oxygen species (ROS) are used by plants as signaling molecules during stress and development. Given the amount of possible challenges a plant face from their environment, plants need to activate and prioritize between potentially conflicting defense signaling pathways. Until recently, most studies on signal interactions have focused on phytohormone interaction, such as the antagonistic relationship between salicylic acid (SA)-jasmonic acid and cytokinin-auxin.ResultsIn this study, we report an antagonistic interaction between SA signaling and apoplastic ROS signaling. Treatment with ozone (O3) leads to a ROS burst in the apoplast and induces extensive changes in gene expression and elevation of defense hormones. However, Arabidopsis thaliana dnd1 (defense no death1) exhibited an attenuated response to O3. In addition, the dnd1 mutant displayed constitutive expression of defense genes and spontaneous cell death. To determine the exact process which blocks the apoplastic ROS signaling, double and triple mutants involved in various signaling pathway were generated in dnd1 background. Simultaneous elimination of SA-dependent and SA-independent signaling components from dnd1 restored its responsiveness to O3. Conversely, pre-treatment of plants with SA or using mutants that constitutively activate SA signaling led to an attenuation of changes in gene expression elicited by O3.ConclusionsBased upon these findings, we conclude that plants are able to prioritize the response between ROS and SA via an antagonistic action of SA and SA signaling on apoplastic ROS signaling.

Defense suppression benefits herbivores that have a monopoly on their feeding site but can backfire within natural communities

BackgroundPlants have inducible defenses to combat attacking organisms. Hence, some herbivores have adapted to suppress these defenses. Suppression of plant defenses has been shown to benefit herbivores by boosting their growth and reproductive performance.ResultsWe observed in field-grown tomatoes that spider mites (Tetranychus urticae) establish larger colonies on plants already infested with the tomato russet mite (Aculops lycopersici). Using laboratory assays, we observed that spider mites have a much higher reproductive performance on russet mite-infested plants, similar to their performance on the jasmonic acid (JA)-biosynthesis mutant def-1. Hence, we tested if russet mites suppress JA-responses thereby facilitating spider mites. We found that russet mites manipulate defenses: they induce those mediated by salicylic acid (SA) but suppress those mediated by JA which would otherwise hinder growth. This suppression of JA-defenses occurs downstream of JA-accumulation and is independent from its natural antagonist SA. In contrast, spider mites induced both JA- and SA-responses while plants infested with the two mite species together display strongly reduced JA-responses, yet a doubled SA-response. The spider mite-induced JA-response in the presence of russet mites was restored on transgenic tomatoes unable to accumulate SA (nahG), but russet mites alone still did not induce JA-responses on nahG plants. Thus, indirect facilitation of spider mites by russet mites depends on the antagonistic action of SA on JA while suppression of JA-defenses by russet mites does not. Furthermore, russet mite-induced SA-responses inhibited secondary infection by Pseudomonas syringae (Pst) while not affecting the mite itself. Finally, while facilitating spider mites, russet mites experience reduced population growth.ConclusionsOur results show that the benefits of suppressing plant defenses may diminish within communities with natural competitors. We show that suppression of defenses via the JA-SA antagonism can be a consequence, rather than the cause, of a primary suppression event and that its overall effect is determined by the presence of competing herbivores and the distinct palette of defenses these induce. Thus, whether or not host-defense manipulation improves an herbivore’s fitness depends on interactions with other herbivores via induced-host defenses, implicating bidirectional causation of community structure of herbivores sharing a plant.

Induced systemic resistance: an innovative control method to manage branched broomrape (Orobanche ramosa L.) in tomato

The biochemical responses of tomato ( Lycopersicon esculentum Mill.) roots to different concentrations of the hormonal elicitors, salicylic acid (SA) and indole acetic acid (IAA), as presoaking treatments, on the healthy and Orobanche ramosa -infected plants were studied in pot experiment under control conditions. Application of SA and IAA activate the production of proline and soluble proteins in tomato roots, where their levels were more pronounced in the infected than the healthy plants. Moreover, both elicitors increased the levels of phenolics and flavonoids accompanied by stimulations in the activities of phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO) in tomato roots, where the magnitude of induction were more obvious in infected plants than healthy one. Also, microscopic examination revealed the anatomical differences observed in both untreated healthy and infected plants as well as in plants treated with SA and IAA. The present results indicate the effectiveness of SA and IAA in enhancing resistance of tomato to retard the incidence of infestation by Orobanche. These biochemical and histological changes involved in plant defense mechanisms may be one of the basic ways participate in the action of SA and IAA for increasing resistance in tomato against Orobanche ramosa . Keywords : Orobanche ramosa ; tomato, Induced resistance, Phenolics, PR-proteins . *Corresponding author : Shahnaz Al-Wakeel (e-mail: shahnazalwakeel@yahoo.com) (Received: 12.04.2012 Accepted: 17.07.2012)

Crosstalk between intracellular and extracellular salicylic acid signaling events leading to long-distance spread of signals

It is well recognized that salicylic acid (SA) acts as a natural signaling molecule involved in both local and systemic plant defense responses upon attacks by pathogens. Recently, cellular SA receptors and a number of SA-related phloem-mobile signals were identified. Here, we compare the old and up-to-date concepts of plant defense signaling events involving SA. Finally, the crosstalk between intracellular and extracellular SA signaling events leading to long-distance spread of signals was outlined by focusing on the modes of both the short- and long-distance signaling events involving the actions of SA. For the above purpose, two distinct conceptual models for local SA perception and signaling mechanisms in the intracellular and extracellular paths (referred to as models i and ii, respectively) were proposed. In addition to two local SA perception models, we propose that the long-distance SA action could be attributed to three different modes, namely, (iii) local increase in SA followed by transport of SA and SA intermediates, (iv) systemic propagation of SA-derived signals with both chemical and electrical natures without direct movement of SA, and (v) integrated crosstalk allowing alternately repeated secondary signal propagation and biosynthesis of SA and/or conversion of inert SA intermediates to free SA finally contributing to the systemic spread of SA-derived signals. We review here that the long-distance SA signaling events (models iii-v), inevitably involve the mechanisms described in the local signaling models (models i and ii) as the key pieces of the crosstalk.

Composite Medicine “Azisal” Based on Azithromycin and Salicylic Acid

Salicylic acid essentially is obtained under the pressure by the method of Kolbe-Schmidt. One of the biggest drawbacks of this method is the necessity of synthesizing sodium phenolate in advance which involves considerable technological difficulties: water predistillation under vacuum and also the dry sodium phenolate getting very hygroscopic. It is therefore of interest to look for more convenient alternative pathways for the synthesis of salicylic acid, excluding the use of sodium phenolate and this drawback is eliminated by using sodium and potassium salts of ethyl carbonic acid as carboxylation body. Consequently, according to the more convenient method we obtained the salicylic acid. In medicine, 1% solution of salicylic acid in 70 % alcohol called salicylic alcohol is used as an antiseptic. We investigated the antimicrobial activity of a 1% solution of salicylic acid in various concentrations of ethanol (40%, 50%, 60%, 70%, 80% and 90%) in order to determine the effect of different concentrations of ethanol on the antimicrobial activity of salicylic acid. The experiment proved that 1% solution of salicylic acid in various concentrations of ethanol (40-90%) to the appropriate strains of bacteria acts with the same activity regardless of the concentration of ethanol (40%, 50%, 60%, 70%, 80% and 90%). These actions of the acid are due to its solubility in alcohols of different concentrations and complete disintegration of salicylic acid molecules into ions. Thus, on the basis of antimicrobial research the necessity of preparation of 1% solution of salicylic acid in 40% alcohol is proved as the drug is cheaper and cost-effective to produce. The technology of the new composition of the drug “Azisal” consisting of 0.25 g azithromycin and 1.0 g salicylic acid in 60% ethanol was developed, in a similar way solution of azithromycin in different concentrations 0.25, 0.5, 0.75, 1.0% in 60% ethanol were prepared and their antimicrobial activities were defined. The comparison of their antimicrobial activity shows the effectiveness of the composite product called “Azisal”.

Diverse Responses Are Involved in the Defence of Arabidopsis thaliana against Turnip Crinkle Virus

Plant hormones play pivotal roles as signals of plant-pathogen interactions. Here, we report that exogenous application of salicylic acid (SA), jasmonic acid (JA), ethephon (ETH), and abscisic acid (ABA) can reduce Turnip crinkle virus (TCV) accumulation in systemic leaves of Arabidopsis thaliana during early infection. SA and ABA are more efficient and confer a longer-lasting resistance against TCV than JA and ETH, and the plant hormones interact in effecting the plant defence. Synergistic actions of SA and JA, and SA and ET, and an antagonistic action of SA and ABA have been observed in the Arabidopsis-TCV interaction. ABA can down-regulate the expression of the pathogenesis-related genes PR1 and PDF1.2, and compared to the wild type, it drastically reduces TCV accumulation in NahG transgenic plants and the eds5-p1 mutant, both of which do not accumulate SA. This indicates that SA signaling negatively regulates the ABA-mediated defence. ABA-induced resistance against TCV is independent of SA. We also found that mitogen-activated protein kinase 5 (MPK5) may be involved in ABA-mediated defence. These results indicate that Arabidopsis can activate distinct signals to inhibit virus accumulation. Cooperative or antagonistic crosstalk between them is pivotal for establishing disease resistance. These results show potential to enhance the plant defence against viruses by manipulating diverse hormones.

Inhibition of green mould in blood orange (Citrus sinensis var. Moro) with salicylic acid treatment

The aim of this study was to find an alternative to synthetic fungicides currently used in the control of devastating fungal pathogen Penicillium digitatum Sacc, the causal agent of green mould disease of blood orange. Antifungal activities of salicylic acid (SA) were investigated against P. digitatum. Treatments consisted of five concentrations (0, 1, 2, 4 and 5 mM). The SA application significantly decreased weight loss percentage and increased life storage of fruits. Also, SA positively affected on post-harvest quality factors including total soluble solids (TSS), titrable acidity, anthocyanin, antioxidant content and pH value. It was observed that treated fruits at a concentration of 5 mM had the highest TSS, titrable acidity, anthocyanin and antioxidant content, and it had the lowest decay and acidity. Thus, these results showed that SA has strong impact on post-harvest decay and fruit quality of blood orange.

Long-distance communication and signal amplification in systemic acquired resistance

Systemic acquired resistance (SAR) is an inducible defense mechanism in plants that confers enhanced resistance against a variety of pathogens. SAR is activated in the uninfected systemic (distal) organs in response to a prior (primary) infection elsewhere in the plant. SAR is associated with the activation of salicylic acid (SA) signaling and the priming of defense responses for robust activation in response to subsequent infections. The activation of SAR requires communication by the primary infected tissues with the distal organs. The vasculature functions as a conduit for the translocation of factors that facilitate long-distance intra-plant communication. In recent years, several metabolites putatively involved in long-distance signaling have been identified. These include the methyl ester of SA (MeSA), the abietane diterpenoid dehydroabietinal (DA), the dicarboxylic acid azelaic acid (AzA), and a glycerol-3-phosphate (G3P)-dependent factor. Long-distance signaling by some of these metabolites also requires the lipid-transfer protein DIR1 (DEFECTIVE IN INDUCED RESISTANCE 1). The relative contribution of these factors in long-distance signaling is likely influenced by environmental conditions, for example light. In the systemic leaves, the AGD2-LIKE DEFENSE RESPONSE PROTEIN1 (ALD1)-dependent production of the lysine catabolite pipecolic acid (Pip), FLAVIN-DEPENDENT MONOOXYGENASE1 (FMO1) signaling, as well as SA synthesis and downstream signaling are required for the activation of SAR. This review summarizes the involvement and interaction between long-distance SAR signals and details the recently discovered role of Pip in defense amplification and priming that allows plants to acquire immunity at the systemic level. Recent advances in SA signaling and perception are also highlighted.

Diverse Responses Are Involved in the Defence of Arabidopsis thaliana against Turnip Crinkle Virus

Plant hormones play pivotal roles as signals of plant-pathogen interactions. Here, we report that exogenous application of salicylic acid (SA), jasmonic acid (JA), ethephon (ETH), and abscisic acid (ABA) can reduce Turnip crinkle virus (TCV) accumulation in systemic leaves of Arabidopsis thaliana during early infection. SA and ABA are more efficient and confer a longer-lasting resistance against TCV than JA and ETH, and the plant hormones interact in effecting the plant defence. Synergistic actions of SA and JA, and SA and ET, and an antagonistic action of SA and ABA have been observed in the Arabidopsis-TCV interaction. ABA can down-regulate the expression of the pathogenesis-related genes PR1 and PDF1.2, and compared to the wild type, it drastically reduces TCV accumulation in NahG transgenic plants and the eds5-p1 mutant, both of which do not accumulate SA. This indicates that SA signaling negatively regulates the ABA-mediated defence. ABA-induced resistance against TCV is independent of SA. We also found that mitogen-activated protein kinase 5 (MPK5) may be involved in ABA-mediated defence. These results indicate that Arabidopsis can activate distinct signals to inhibit virus accumulation. Cooperative or antagonistic crosstalk between them is pivotal for establishing disease resistance. These results show potential to enhance the plant defence against viruses by manipulating diverse hormones.

Induction of Systemic Acquired Resistance by Heat Shock Treatment inArabidopsis

Systemic acquired resistance (SAR) is a potent innate immunity system in plants and has been used in rice fields. Development of SAR, involving priming, is achieved by activation of salicylic acid (SA)-mediated pathway. To determine whether heat shock (HS) treatment can induce SAR, we analyzed the effects of HS on Arabidopsis. HS treatment induced disease resistance, expression of SAR marker genes, and SA accumulation in wild-type but not in SA-deficient sid2 and NahG plants, indicating induction of SAR. Time course analysis of the effects of HS indicated that SAR was activated transiently, differently from biological induction, with a peak at 2-3 d after HS, and that it ceased in several days. Production of reactive oxygen species was observed before SA biosynthesis, which might be a trigger for SAR activation. The data presented here suggest that HS can induce SAR, but there exist unknown regulation mechanisms for the maintenance of SAR.

The combined use of photoaffinity labeling and surface plasmon resonance‐based technology identifies multiple salicylic acid‐binding proteins

Salicylic acid (SA) is a small phenolic molecule that not only is the active ingredient in the multi-functional drug aspirin, but also serves as a plant hormone that affects diverse processes during growth, development, responses to abiotic stresses and disease resistance. Although a number of SA-binding proteins (SABPs) have been identified, the underlying mechanisms of action of SA remain largely unknown. Efforts to identify additional SA targets, and thereby elucidate the complex SA signaling network in plants, have been hindered by the lack of effective approaches. Here, we report two sensitive approaches that utilize SA analogs in conjunction with either a photoaffinity labeling technique or surface plasmon resonance-based technology to identify and evaluate candidate SABPs from Arabidopsis. Using these approaches, multiple proteins, including the E2 subunit of α-ketoglutarate dehydrogenase and the glutathione S-transferases GSTF2, GSTF8, GSTF10 and GSTF11, were identified as SABPs. Their association with SA was further substantiated by the ability of SA to inhibit their enzymatic activity. The photoaffinity labeling and surface plasmon resonance-based approaches appear to be more sensitive than the traditional approach for identifying plant SABPs using size-exclusion chromatography with radiolabeled SA, as these proteins exhibited little to no SA-binding activity in such an assay. The development of these approaches therefore complements conventional techniques and helps dissect the SA signaling network in plants, and may also help elucidate the mechanisms through which SA acts as a multi-functional drug in mammalian systems.

Potential of salicylic acid activity derived from stress-induced (water) Tomato against Meloidogyne incognita

Plants have evolved several types of sophisticated defence mechanisms to protect themselves from enemies in which the signalling molecules such as salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) often play crucial roles. An experiment was conducted to investigate the water induced stress in young tomato plants (Lycopersicon esculentum var. Pusa Ruby) during water deprivation and after relief from stress in association with salicylic acid. Application of SA or certain analogues such as aspirin induces expression of pathogenesis-related proteins (PR) in plants which serve as molecular markers for the systemic acquired response (SAR). In plants, the production of reactive oxygen species (ROS), such as superoxide radical (O2), hydroxyl radical (OH) and hydrogen peroxide (H2O2), is also common in metabolic and physiological processes. Similar to the defence-regulating compounds such as SA and JA, plant-derived ET is also known to be involved in disease resistance. The role of ROS or ET could be investigated which was carried out in the present study to know the osmotic stress mediated resistance by SA against Meloidogyne incognita in tomato plants.

The Long-Sought-After Salicylic Acid Receptors

The Long-Sought-After Salicylic Acid Receptors

Insights into salicylic acid responses in cucumber (Cucumis sativus L.) cotyledons based on a comparative proteomic analysis

To investigate the response of cucumber seedlings to exogenous salicylic acid (SA) and gain a better understanding of SA action mechanism, we generated a proteomic profile of cucumber (Cucumis sativus L.) cotyledons treated with exogenous SA. Analysis of 1500 protein spots from each gel revealed 63 differentially expressed proteins, 59 of which were identified successfully. Of the identified proteins, 97% matched cucumber proteins using a whole cucumber protein database based on the newly completed genome established by our laboratory. The identified proteins were involved in various cellular responses and metabolic processes, including antioxidative reactions, cell defense, photosynthesis, carbohydrate metabolism, respiration and energy homeostasis, protein folding and biosynthesis. The two largest functional categories included proteins involved in antioxidative reactions (23.7%) and photosynthesis (18.6%). Furthermore, the SA-responsive protein interaction network revealed 13 key proteins, suggesting that the expression changes of these proteins could be critical for SA-induced resistance. An analysis of these changes suggested that SA-induced resistance and seedling growth might be regulated in part through pathways involving antioxidative reactions and photosynthesis.

Interactive effects of salicylic acid and nitric oxide on soybean plants under NaCl salinity

The effects of salicylic acid (SA), sodium nitroprusside (SNP), a nitric oxide donor, and their combination (SA+SNP) on some physiological parameters of 23-day-old soybean seedlings grown under saline and nonsaline conditions were studied. The changes in the leaf area, shoot fresh and dry weights, contents of chlorophylls and carotenoids, amounts of MDA and hydrogen peroxide showed that the addition of 100 μM SA and/or 100 μM SNP markedly declined the oxidative damage to soybean plants induced by 50 and 100 μM NaCl. Our results proved that combined action of SA and nitric oxide donor significantly activated catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX), which contributed to the decay of H2O2 in soybean leaves under NaCl toxicity. The protective action of (SA+SNP) against saltinduced oxidative damage was often more efficient than effects of SA and SNP alone. We also observed that the accumulation of proline was apparently accelerated by these substances under salt stress. As well, it was observed that the interaction between SA and nitric oxide had synergistic effects in decreasing of the damages induced by NaCl salinity.

Effect of salicylic acid on the proton translocation activity of plasmalemma of potato tuber cells

Action of salicylic acid (SA) on the activity of membrane bound H(+)-ATPase and passive proton permeability of plasmalemma membrane vesicles (PMV) from parenchyma cells of potato tubers was detected. A correlation between SA action and germination of tubers and activity of plasmalemma H(+)-ATPase was revealed: the application of growth-stimulating concentrations of SA (10(-10)-10(-8) M) in the system in vitro resulted in activation of plasmalemma H(+)-ATPase, while the utilization of growth-inhibiting concentrations (10(-4), 10(-5) M) provoked inhibition of the enzyme activity. Addition of jasmonic acid (JA) to the incubation mix resulted in increase of SA effect on the accumulation of H+ in PMV.

Accumulation of Isochorismate-derived 2,3-Dihydroxybenzoic 3-O-β-d-Xyloside in Arabidopsis Resistance to Pathogens and Ageing of Leaves

An intricate network of hormone signals regulates plant development and responses to biotic and abiotic stress. Salicylic acid (SA), derived from the shikimate/isochorismate pathway, is a key hormone in resistance to biotrophic pathogens. Several SA derivatives and associated modifying enzymes have been identified and implicated in the storage and channeling of benzoic acid intermediates or as bioactive molecules. However, the range and modes of action of SA-related metabolites remain elusive. In Arabidopsis, Enhanced Disease Susceptibility 1 (EDS1) promotes SA-dependent and SA-independent responses in resistance against pathogens. Here, we used metabolite profiling of Arabidopsis wild type and eds1 mutant leaf extracts to identify molecules, other than SA, whose accumulation requires EDS1 signaling. Nuclear magnetic resonance and mass spectrometry of isolated and purified compounds revealed 2,3-dihydroxybenzoic acid (2,3-DHBA) as an isochorismate-derived secondary metabolite whose accumulation depends on EDS1 in resistance responses and during ageing of plants. 2,3-DHBA exists predominantly as a xylose-conjugated form (2-hydroxy-3-beta-O-D-xylopyranosyloxy benzoic acid) that is structurally distinct from known SA-glucose conjugates. Analysis of DHBA accumulation profiles in various Arabidopsis mutants suggests an enzymatic route to 2,3-DHBA synthesis that is under the control of EDS1. We propose that components of the EDS1 pathway direct the generation or stabilization of 2,3-DHBA, which as a potentially bioactive molecule is sequestered as a xylose conjugate.

Salicylic acid improves podophyllotoxin production in cell cultures of Linum album by increasing the expression of genes related with its biosynthesis

Treatment of Linum album cell cultures with 10 μM salicylic acid (SA) for 3 days improved podophyllotoxin (PTOX) production up to 333 μg/g dry weight (DW): over three times that of the control cultures. qPCR analyses showed that in SA-treated cells, the expression of the genes coding for phenylalanine ammonia-lyase (PAL), cinnamoyl-CoA reductase (CCR) and cinnamyl-alcohol dehydrogenase (CAD), all involved in the first steps of PTOX biosynthesis, also increased reaching a peak 8-12 h after the treatment. Expression of the pinoresinol-lariciresinol reductase gene (PLR), which is involved in one of the last biosynthetic steps, was not affected by SA. The selective action of SA on these genes can be applied to control the biotechnological production of this anticancer agent.

Alteration in phosphate uptake potential of wheat plants co-cultivated with salicylic acid

The phosphate uptake potential was significantly stimulated with low concentration of salicylic acid (SA). In one of the wheat cultivars ( Triticum aestivum Var. Sonalika), 50 μM SA stimulated phosphate (PO 4 3−) uptake. At higher concentrations of SA (500 and 1000 μM), the rate of uptake was reduced. These findings underscore the light and dose-dependent biphasic action of SA: a low 50 μM stimulated, and high concentrations 500 and 1000 μM inhibited, PO 4 3− uptake.