Salicylic acid-mediated changes in photosynthesis,nutrients content and antioxidant metabolism in two mustard (<Emphasis Type="Italic">Brassica juncea</Emphasis> L.) cultivars differing in salt tolerance

Mustard (Brassica juncea L.) cultivars Alankar (salt-tolerant) and PBM16 (salt-sensitive) plants were grown with 50 mM NaCl and were sprayed with 0.1, 0.5, and 1.0 mM salicylic acid (SA) to study the physiological processes determining salt tolerance and to observe the influence of SA application on the alleviation of NaCl-induced adverse effects. The content of leaf Na⁺, Cl⁻, H₂O₂, TBARS, and electrolyte leakage and the activity of SOD were higher in PBM16 than Alankar. In contrast, nutrients content, activity of APX and GR, glutathione content, photosynthetic and growth characteristics were higher in Alankar. Treatment of 50 mM NaCl resulted in increase of Na⁺ and Cl⁻, oxidative stress, activity of antioxidant enzymes and glutathione content, while nutrients content, photosynthetic, and growth characteristics decreased in both the cultivars. Application of 0.5 mM SA alleviated the negative effects of 50 mM NaCl maximally, but 1.0 mM SA proved inhibitory. The effect of SA was more conspicuous in Alankar than PBM16. It is concluded that the higher tolerance of Alankar was due to its lower leaf Na⁺ and Cl⁻ content, higher nutrients content, and efficient antioxidant metabolism. The application of 0.5 mM SA substantially alleviated salt-induced adverse effects in Alankar.     

Influence of salicylic acid and Glomus fasciculatum on fusarial wilt of tomato and brinjal

Wilt of tomato caused by Fusarium oxysporum f.sp. lycopersici and wilt of brinjal caused by Fusarium solani are very common in different agricultural fields of West Bengal, India. The study on the effect of salicylic acid (SA) on in vitro growth of the pathogens revealed that SA completely checks the growth at 0.7 mM concentration and above. On the other hand, the percentage of mycorrhisation in the host plants with an arbuscular mycorrhizal (AM) fungus, Glomus fasciculatum was found to be decreased in the presence of SA in the plants with or without pathogenic infection. Treatment of tomato and brinjal plants either singly with AM fungus or with SA (0.5 and 1.0 mM) and also with their combined treatment showed amelioration of plant height, length of root, fresh weight of root and fresh weight of plants. However, the AM fungus-treated plants showed highest growth responses. The result also reveals that integrated treatment with AM plus SA has significant effect on reduction of infection where application of AM + SA (1.0 mM) resulted in 67.16 and 69.70% reduction of fusarial wilt infection in tomato and brinjal plants, respectively.     

Effect of salicylic acid pretreatment on drought stress responses of zoysiagrass (Zoysia japonica)

The present study was carried out to examine the effects of exogenous salicylic acid (SA) on growth, activities of antioxidant enzymes, and some physiological and biochemical characteristics of zoysiagrass (Zoysia japonica Steud.) plants subjected to drought. Aqueous 0.1, 0.5, or 1.0 mM SA solution was sprayed on the leaves of zoysiagrass for 3 days. Drought was induced by withholding watering for 16 days after SA application. Biomass, chlorophyll content, net photosynthetic rate (P _n), activities of antioxidant enzymes (e.g., superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), MDA and proline contents were determined. Pretreatments with 0.1 and 0.5 mM SA significantly increased fresh and dry weights and chlorophyll content, while 1 mM SA pretreatment did not show significant change compared to controls. SA pretreatments showed a marked increase in P _n compared with controls from the 7th to 16th day after drought start. Activities of SOD, POD, and CAT were increased by SA pretreatments. MDA and proline contents after 0.1 and 0.5 mM pretreatments were lower than those of controls from the 6th to 12th day of drought, while 1 mM SA pretreatment did not show significant change from the 0th to 9th day of drought. This work suggests that suitable exogenous SA (0.5 mM) helps zoysiagrass to perform better under drought stress by enhancing the net photosynthetic rate and antioxidant enzyme activities while decreasing lipid peroxidation as compared to the controls. SA could be used as a potential growth regulator for improving plant growth under drought stress.     

Seed treatment with salicylic acid invokes defence mechanism of Helianthus annuus against Orobanche cumana

The root holoparasitic angiosperm sunflower broomrape (Orobanche cumana) specifically affects sunflower (Helianthus annuus) growth and causes severe damage all over the world. This investigation was designed to examine the protective effects of salicylic acid (SA) treatment to the seeds of an O. cumana‐susceptible cultivar of sunflower (TK0409). Sunflower seeds were pretreated with different concentrations (0, 0.5 and 1 mM) of SA and inoculated with O. cumana for 4 weeks. O. cumana infection resulted in reduction in plant biomass, endogenous SA level, and the expression of SA‐related genes including pal, chs and NPR1. By contrast, O. cumana infection enhanced the production of reactive oxygen species, activities of antioxidant enzymes as well as contents of phenolics and lignin. Seed treatment with 1 mM SA increased sunflower biomass in terms of plant height, fresh weight and dry weight by 10%, 13% and 26%, respectively, via reducing the number and biomass of established O. cumana. The increase of hydrogen peroxide contents by 14% in the 1 mM SA treated sunflower plants appeared to be because of the inhibition of ascorbate peroxidase and catalase by exogenous SA. The enhanced expression of pathogenesis‐related genes (PR3 and PR12, encoding chitinase and defensin, respectively) after 4 weeks of inoculation indicated that systemic acquired resistance was induced in the SA treated sunflower in which the level of endogenous SA was also elevated in a dose‐dependent manner. The increased expression of a hypersensitive‐responsive (HR) gene hsr indicated that the resistance of sunflowers might be associated with a hypersensitive reaction which was activated by exogenous SA treatment.     

Exogenous salicylic acid regulates reactive oxygen species metabolism and ascorbate–glutathione cycle in <Emphasis Type="Italic">Nitraria tangutorum</Emphasis> Bobr. under salinity stress

The effect of 0.5–1.5 mM salicylic acid (SA) on modulating reactive oxygen species metabolism and ascorbate–glutathione cycle in NaCl-stressed Nitraria tangutorum seedlings was investigated. The individual plant fresh weight (PFW) and plant dry weight (PDW) significantly increased under 100 mM NaCl while remained unchanged or decreased under 200–400 mM NaCl compared to the control. Superoxide anion (O ₂ ^·? ), hydrogen peroxide (H₂O₂), thiobarbituric acid reactive substances (TBARS), reduced ascorbate (AsA), dehydroascorbate (DHA), reduced glutathione (GSH) and oxidized glutathione (GSSG) increased whereas the ratios of AsA/DHA and GSH/GSSG decreased under varied NaCl treatments. Ascorbate peroxidase (APX) and glutathione reductase (GR) activities were enhanced while dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activities remained unvaried under 100–400 mM NaCl stresses. In addition, exogenous SA further increased PFW, PDW and root/shoot ratio. SA effectively diminished O ₂ ^·? accumulation. H₂O₂ and TBARS decreased under 0.5 and 1.0 mM SA treatments compared to those without SA. 0.5 mM of SA increased while 1.0 and 1.5 mM SA decreased APX activities. DHAR activities were elevated by 0.5 and 1.0 mM SA but not by 1.5 mM SA. MDHAR and GR activities kept constant or significantly increased at varying SA concentrations. Under SA treatments, AsA and GSH contents further increased, DHA and GSSG levels remained unaltered, while the decreases in AsA/DHA and GSH/GSSG ratios were inhibited. The above results demonstrated that the enhanced tolerance of N. tangutorum seedlings conferred by SA could be attributed mainly to the elevated GR and DHAR activities as well as the increased AsA/DHA and GSH/GSSG ratios.     

Salicylic acid activates artemisinin biosynthesis in <Emphasis Type="Italic">Artemisia annua</Emphasis> L.

This paper provides evidence that salicylic acid (SA) can activate artemisinin biosynthesis in Artemisia annua L. Exogenous application of SA to A. annua leaves was followed by a burst of reactive oxygen species (ROS) and the conversion of dihydroartemisinic acid into artemisinin. In the 24 h after application, SA application led to a gradual increase in the expression of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene and a temporary peak in the expression of the amorpha-4,11-diene synthase (ADS) gene. However, the expression of the farnesyl diphosphate synthase (FDS) gene and the cytochrome P450 monooxygenase (CYP71AV1) gene showed little change. At 96 h after SA (1.0 mM) treatment, the concentration of artemisinin, artemisinic acid and dihydroartemisinic acid were 54, 127 and 72% higher than that of the control, respectively. Taken together, these results suggest that SA induces artemisinin biosynthesis in at least two ways: by increasing the conversion of dihydroartemisinic acid into artemisinin caused by the burst of ROS, and by up-regulating the expression of genes involved in artemisinin biosynthesis.     

Salicylic Acid Application Mitigates Oxidative Damage and Improves the Growth Performance of Barley under Drought Stress

Drought is a severe environmental constraint, causing a significant reduction in crop productivity across the world. Salicylic acid (SA) is an important plant growth regulator that helps plants cope with the adverse effects induced by various abiotic stresses. The current study investigated the potential effects of SA on drought tolerance efficacy in two barley (Hordeum vulgare) genotypes, namely BARI barley 5 and BARI barley 7. Ten-day-old barley seedlings were exposed to drought stress by maintaining 7.5% soil moisture content in the absence or presence of 0.5, 1.0 and 1.5 mM SA. Drought exposure led to severe damage to both genotypes, as indicated by phenotypic aberrations and reduction of dry biomass. On the other hand, the application of SA to drought-stressed plants protected both barley genotypes from the adverse effects of drought, which was reflected in the improvement of phenotypes and biomass production. SA supplementation improved relative water content and proline levels in drought-stressed barley genotypes, indicating the osmotic adjustment functions of SA under water-deficit conditions. Drought stress induced the accumulation of reactive oxygen species (ROS), such as hydrogen peroxide (H₂O₂) and superoxide (O₂ ^•− ), and the lipid peroxidation product malondialdehyde (MDA) in the leaves of barley plants. Exogenous supply of SA reduced oxidative damage by restricting the accumulation of ROS through the stimulation of the activities of key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX). Among the three-applied concentrations of SA, 0.5 mM SA exhibited better mitigating effects against drought stress considering the phenotypic performance and biochemical data. Furthermore, BARI barley 5 showed better performance under drought stress than BARI barley 7 in the presence of SA application. Collectively, our results suggest that SA played a crucial role in improving water status and antioxidant defense strategy to protect barley plants from the deleterious effects of water deficiency.     

Effects of salicylic acid and salinity on apoplastic antioxidant enzymes in two wheat cultivars differing in salt tolerance

The effects of salicylic acid (SA) and salinity on the activity of apoplastic antioxidant enzymes were studied in the leaves of two wheat (Triticum aestivam L.) cultivars: salt-tolerant (Gerek-79) and salt-sensitive (Bezostaya). The leaves of 10-d-old seedlings grown at nutrient solution with 0 (control), 250 or 500 mM NaCl were sprayed with 0.01 or 0.1 mM SA. Then, the activities of catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) were determined in the fresh leaves obtained from 15-d-old seedlings. The NaCl applications increased CAT and SOD activities in both cultivars, compared to those of untreated control plants. In addition, the NaCl increased POX activity in the salt-tolerant while decreased in the salt-sensitive cultivar. In control plants of the both cultivars, 0.1 mM SA increased CAT activity, while 0.01 mM SA slightly decreased it. SA treatments also stimulated SOD and POX activity in the salt-tolerant cultivar but significantly decreased POX activity and had no effect on SOD activity in the saltsensitive cultivar. Under salinity, the SA treatments significantly inhibited CAT activity, whereas increased POX activity. The increases in POX activity caused by SA were more pronounced in the salt-tolerant than in the salt-sensitive cultivar. SOD activity was increased by 0.01 mM SA in the salt-tolerant while increased by 0.1 mM SA treatment in the salt-sensitive cultivar.     

The role of salicylic acid in response of two rice cultivars to chilling stress

Two rice (Oryza sativa L.) cultivars differing in chilling sensitivity, Changbaijiu (chilling-tolerant) and Zhongjian (chilling-sensitive) were pre-treated with 0.5, 1.0 and 2.0 mM salicylic acid (SA) for 24 h before chilling at 5°C for 1 d. Chilling induced SA accumulation, particularly conjugated SA in both leaves and roots of the two rice cultivars. After SA administration, SA accumulated in the roots of both cultivars at a concentration-dependent manner, whereas only a slight increase was observed in their leaves. Conjugated SA accounted for most of the increase. The beneficial effect of SA treatment on protecting rice seedlings from chilling injury was not observed at any concentration in either cultivar. Pre-treatment with SA even decreased their chilling tolerance confirmed by increased electrolyte leakage and lipid peroxidation. Further, most of the activities of antioxidant enzymes decreased or remained unchanged in leaves and roots of SA pre-treated seedlings after chilling. These results implied that down-regulation of antioxidant defence might be involved in the reduction of chilling tolerance in SA-pre-treated plants.     

Salicylic acid induces stomatal closure by modulating endogenous hormone levels in cucumber cotyledons

Salicylic acid (SA) is one of the most important signaling molecules in plant growth and defense responses to biotic and abiotic stresses. Here, the effect of exogenous SA on the stomatal movements was investigated in cotyledons of cucumber (Cucumis sativus L.) seedlings. Application of different SA concentrations could induce the reduction in stomatal aperture and conductance, especially at a concentration of 0.5 mM. Using the isolated epidermal strips, stomata were found to close notably in response to exogenous SA, even at a concentration as low as 0.001 mM. Further study showed that a SA-induced decrease in the stomatal aperture was intensified by the higher SA concentrations, longer exposure, and lower pH of the medium. In addition, to understand the relationship between stomatal closure and endogenous hormone contents, the levels of ABA, IAA, and gibberellin (GA₃) were assayed under SA treatment. SA significantly increased endogenous ABA but not IAA and GA₃ content. A significant negative correlation (p ≤ 0.01) was observed between stomatal conductance and the ratio of ABA to (GA₃ + IAA) during SA application. It was suggested that exogenous SA could change the balance of endogenous hormones and thereby induce stomatal closure in cotyledons of cucumber seedlings.     

A chlorophyll fluorescence analysis of photosynthetic efficiency, quantum yield and photon energy dissipation in PSII antennae of Lactuca sativa L. leaves exposed to cinnamic acid

This study investigated the effects of cinnamic acid (CA) on growth, biochemical and physiological responses of Lactuca sativa L. CA (0.1, 0.5, 1.0 and 1.5 mM) treatments decreased plant height, root length, leaf and root fresh weight, but it did not affect the leaf water status. CA treatment (1.5 mM) significantly reduced F_v, F_m, photochemical efficiency of PSII (F_v/F_m) and quantum yield of PSII (ΦPSII) photochemistry in L. sativa. The photochemical fluorescence quenching (qP) and non-photochemical quenching (NPQ) were reduced after treatment with 1.5 mM CA. Fraction of photon energy absorbed by PS II antennae trapped by “open” PS II reaction centers (P) was reduced by CA (1.5 mM) while, portion of absorbed photon energy thermally dissipated (D) and photon energy absorbed by PSII antennae and trapped by “closed” PSII reaction centers (E) was increased. Carbon isotope composition ratios (δ¹³C) was less negative (−27.10) in CA (1.5 mM) treated plants as compared to control (−27.61). Carbon isotope discrimination (Δ¹³C) and ratio of intercellular CO₂ concentration (ci/ca) from leaf to air were also less in CA treated plants. CA (1.5 mM) also decreased the leaf protein contents of L. sativa as compared to control.     

Hydroponic treatment with salicylic acid decreases the effects of chilling injury in maize (Zea mays L.) plants

The addition of 0.5 mM salicylic acid (SA) to the hydroponic growth solution of young maize (Zea mays L.) plants under normal growth conditions provided protection against subsequent low-temperature stress. This observation was confirmed by chlorophyll fluorescence parameters and electrolyte leakage measurements. In addition, 1 d of 0.5 mM SA pre-treatment decreased net photosynthesis, stomatal conductivity and transpiration at the growth temperature (22/20 °C). Since there was only a slight decrease in the ratio of variable to maximal fluorescence (F_v/F_m) the decrease in photosynthetic activity is not due to a depression in photosystem II. The analysis of antioxidant enzymes showed that whereas SA treatment did not cause any change in ascorbate peroxidase (EC 1.11.1.11) and superoxide dismutase (EC 1.15.1.1) activities, there was a decrease in catalase (EC 1.11.1.6) activity, and an increase in guaiacol peroxidase (EC 1.11.1.7) and glutathione reductase (EC 1.6.4.2) activities after the 1-d SA treatment at 22/20 °C. In native polyacrylamide gels there was, among the peroxidase isoenzymes, a band which could be seen only in SA-treated plants. It is suggested that the pre-treatment of maize plants with SA at normal growth temperature may induce antioxidant enzymes which lead to increased chilling tolerance. Received: 4 June 1998 / Accepted: 23 November 1998     

Acetyl salicylic acid (Aspirin) and salicylic acid induce multiple stress tolerance in bean and tomato plants

The hypothesis that physiologically activeconcentrations of salicylic acid (SA) and itsderivatives can confer stress tolerance in plants wasevaluated using bean (Phaseolus vulgaris L.) andtomato (Lycopersicon esculentum L.). Plantsgrown from seeds imbibed in aqueous solutions (0.1--0.5 mM) of salicylic acid or acetyl salicylic acid(ASA) displayed enhanced tolerance to heat, chillingand drought stresses. Seedlings acquired similarstress tolerance when SA or ASA treatments wereapplied as soil drenches. The fact that seedimbibition with SA or ASA confers stress tolerance inplants is more consistent with a signaling role ofthese molecules, leading to the expression oftolerance rather than a direct effect. Induction ofmultiple stress tolerance in plants by exogenousapplication of SA and its derivatives may have asignificant practical application in agriculture,horticulture and forestry.     

Efficient induction of microspore embryogenesis using abscisic acid,jasmonic acid and salicylic acid in Brassica napus L

The stress hormones abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) play an important role in the regulation of physiological processes and are often used in tissue culture to promote somatic embryogenesis and to enhance the quality of somatic embryos. Despite many studies on Brassica napus microspore culture, the effects of stress hormones (ABA, JA and SA) on microspore embryogenesis are not well explored. In this study, the effects of three incubation periods (6, 12 and 24 h) at different levels of ABA, JA and SA (0, 0.2, 0.5, 1.0, 2.0 and 5.0 mg l^?1) on microspore embryogenesis of rapeseed (B. napus L.) cv. ‘Regent’ were investigated. ABA (0.5 mg l^?1 for 12 h) enhanced microspore embryogenesis by about threefold compared with untreated cultures and increased normal plantlet regeneration by 68 %. ABA treatment also effectively reduced secondary embryo formation at all concentrations tested but enhanced callusing at high levels, for example 67 % at 1.0 mg l^?1 for 24 h. Highest embryo yield (286.0 embryos Petri dish^?1) was achieved using 1.0 mg l^?1 JA for 24 h and highest normal plantlet regeneration (54 %) was observed in cultures exposed to 0.5 mg l^?1 JA for 12 h. JA (5.0 mg l^?1 for 24 h) also reduced the germination of microspore-derived embryos on regeneration medium by 21 %. SA at 0.2 and 0.5 mg l^?1 for 6 h increased microspore embryogenesis (184.0 and 193.4 embryos Petri dish^?1) relative to the control (136.2 embryos Petri dish^?1). However, SA did not improve normal regeneration, secondary embryo formation or callusing. Microspore embryogenesis and plant regeneration could be improved by ABA, JA as well as SA when the appropriate level and duration of incubation were selected.     

Combined Effect of Salicylic Acid and Nitrogen Oxide Donor on Stress-Protective System of Wheat Plants under Drought Conditions

Presowing treatment of wheat (Triticum aestivum L.) seeds with 10 or 100 μM salicylic acid (SA) reduced the inhibition of 14-day-old plant growth under soil drought. The same effect was caused by the spraying of 7-day-old seedlings with 0.5 or 2 mM nitrogen oxide donor (sodium nitroprusside, SNP) before drought. The protective effect was enhanced by the combination of seed treatment with 10 μM SA and plant spraying with 0.5 mM SNP, while their combinations in higher concentrations caused weaker effects. SA treatment in both concentrations and 0.5 mM SNP under drought conditions increased the antioxidant enzyme activity (superoxide dismutase, catalase, and guaiacol peroxidase) in leaves. This effect was especially significant when 10 μM SA was combined with 0.5 mM SNP. Spraying with 2 mM SNP and its combination with seed presowing with 100 μM SA did not significantly change the antioxidant enzyme activity; however, the proline content in the leaves increased. It is concluded that the SA stress-protective action on plants can be modified with exogenous nitrogen oxide.     

Induction of astaxanthin formation by reactive oxygen species in mixotrophic culture of Chlorococcum sp.

The induction of astaxanthin formation by reactive oxygen species in mixotrophic culture of Chlorococcum sp. was investigated. H₂O₂ (0.1 mM) enhanced the total astaxanthin formation from 5.8 to 6.5 mg g^–1 cell dry wt. Fe²⁺ (0.5 mM) added to the medium with H₂O₂ (0.1 mM) further promoted astaxanthin formation to 7.1 mg g^–1 cell dry wt. Similarly, Fe²⁺ (0.5 mM) together with methyl viologen (0.01 mM) promoted astaxanthin formation to 6.3 mg g^–1 cell dry wt. In contrast, an addition of KI (1 mM), a specific scavenger for hydroxyl radicals (OH), together with H₂O₂ (0.1 mM) and Fe²⁺ (0.5 mM), to the medium decreased astaxanthin formation to 1.8 mg g^–1 cell dry wt. KI (1 mM) also inhibited the enhancement of carotenogenesis by superoxide anion radicals (O₂ ^–), with a decrease of astaxanthin formation to 1.7 mg g^–1 cell dry wt. This suggested that O₂ ^– might be transformed to OH before promoting carotenogenesis in Chlorococcum sp.     

Treatment with acetyl salicylic acid protects muskmelon seedlings against drought stress

Salicylic acid (SA) is a common plant-produced signal molecule that is responsible for inducing tolerance to a number of biotic and abiotic stresses. An experiment was, therefore, conducted to test whether acetyl salicylic acid (ASA) application at various concentrations through seed soaking or foliar spray would protect muskmelon [Cucumis melo L. (reticulatus group)] seedlings, subjected to drought stress. Twenty-three-day-old plants pre-treated with ASA (0, 0.1, 0.25, 0.50 or 1.0 mM) were subjected to drought stress for 1 week in a greenhouse. ASA applied either through seed soaking or through foliar spray was effective within the range of 0.1–1 mM in providing drought stress protection in muskmelon seedlings; however, there was no difference between application methods indicating that both methods provided similar levels of protection. ASA significantly affected all seedling growth and stress indicator variables measured except leaf number and root dry weight. The best protection appeared to be obtained from seedlings pre-treated with lower concentrations of ASA. Even though both methods provided similar means of protection, due to its simplicity and practicality, soaking muskmelon seeds prior to sowing in up to 0.5 mM ASA would be a more desirable method.     

The effect of methyl salicylate on the induction of direct and indirect plant defense mechanisms in poplar (Populus × euramericana ‘Nanlin 895’)

The objective of this study was to investigate the effect of different concentrations of methyl salicylate (MeSA) on direct defense and indirect defense in poplar cuttings (Populus × euramericana ‘Nanlin 895’). Four defense-related enzyme activities, such as superoxide dismutase (SOD, EC1.15.1.1), oxydoreductases peroxidase (POD, EC1.11.1.7), catalase (CAT, EC1.11.1.6), and polyphenol oxidase (PPO, EC 1.14.18.1), were measured. The results showed that the SOD activities were induced by 1.0 and 10.0 mM MeSA and the POD activities were induced by MeSA. The CAT activity was induced at low concentrations of MeSA but was inhibited by high concentrations, and the PPO activity was affected by 0.1, 1.0, and 10.0 mM MeSA. Furthermore, the volatiles were detected using gas chromatography–mass spectrometry and gas chromatography. Twenty-one volatile compounds were tentatively identified in the emissions from plant leaves. Of these volatile compounds, (Z)-3-hexen-1-ol and cis-3-hexenyl acetate emissions were the highest. (Z)-3-Nonen-1-ol, (E)-2-hexen-1-ol, 1-octanol, (E,Z)-3,6-nonadien-1-ol, β-ionone, and hexadecanamide were six compounds that were only produced after treatment by 10.0 mM MeSA. These results showed that direct and indirect defense mechanisms in poplars were induced by MeSA.     

Production of potential anti-inflammatory compounds in cell suspension cultures of <Emphasis Type="Italic">Sphaeralcea angustifolia</Emphasis> (Cav.) G. Don

Sphaeralcea angustifolia is used in Mexican traditional medicine to treat inflammatory processes. SCopoletin (SC), TOmentin (TO), and sphaeralcic acid (SA) were reported as the main anti-inflammatory compounds in this species. The aim of this study was to establish in vitro conditions for the development of calli and cell suspension cultures that are the producers of these active compounds. Callus cultures of plant leaf explants were set up using different auxin levels of α-naphthalene acetic acid (NAA) in combination with a constant concentration (0.1 mg L^?1) of Kinetin (Kn) in Murashige and Skoog (MS) medium. Optimal combinations for callus induction were 1.0 and 2.0 mg L^?1 of NAA. SC, TO, and SA were not detected in callus tissues. Employing a 4 % inoculum in fresh biomass, cell suspension was established from friable callus with 1.0 mg L^?1 of NAA in combination with 0.1 mg L^?1 of Kn in MS liquid medium (27.4 mM nitrate). The cellular suspension synthesized SC and SA, SC was excreted into the culture medium, while SA was excreted into the culture medium and accumulated in biomass. To improve SC and SA production, total nitrate content was reduced in MS medium. On diminishing nitrate content to 2.74 mM, cellular suspension growth was not modified. SC concentration (0.04 %) was 60-fold higher than that detected in the wild plant (0.00067 %), TO was produced (0.096 %), and SA content (0.0036 %) was not improved. SA production in MS medium with 0.274 mM nitrate (0.004 %) was enriched 12-fold (0.0003 %) in relation to that of the wild plant. The anti-inflammatory effects at 5 h of intraperitoneal (i.p.) administration (100 mg per kg BW) of dichloromethane extracts from the medium (42 ± 3 %) and biomass (39 ± 9.3 %) of S. angustifolia cell suspensions cultivated in MS with 2.74 mM nitrate were similar. The effect of the biomass dichloromethane extract was dose dependent with a median Effective Dose (ED₅₀) of 137.63 mg per kg BW.