Mechanism Of Salicylic Acid Research Articles

Anti-Oomycete Effect and Mechanism of Salicylic Acid on Phytophthora infestans.

Pathogenic oomycetes infect a wide variety of organisms, including plants, animals, and humans, and cause massive economic losses in global agriculture, aquaculture, and human health. Salicylic acid (SA), an endogenous phytohormone, is regarded as an inducer of plant immunity. Here, the potato late blight pathogen Phytophthora infestans was used as a model system to uncover the inhibitory mechanisms of SA on pathogenic oomycetes. In this research, SA significantly inhibited the mycelial growth, sporulation, sporangium germination, and virulence of P. infestans. Inhibition was closely related to enhanced autophagy, suppression of translation initiation, and ribosomal biogenesis in P. infestans, as shown by multiomics analysis (transcriptomics, proteomics, and phosphorylated proteomics). Monodansylcadaverine (MDC) staining and Western blotting analysis showed that SA promoted autophagy in P. infestans by probably targeting the TOR signaling pathway. These observations suggest that SA has the potential to control late blight caused by P. infestans.

Mechanism of salicylic acid in promoting the rhizosphere benzo[a]pyrene biodegradation as revealed by DNA-stable isotope probing

Benzo[a]pyrene (BaP) is a typical high-molecular-weight PAH with carcinogenicity. Rhizoremediation is commonly applied to remove soil BaP, but its mechanism remains unclear. The role of inducers in root exudates in BaP rhizoremediation is rarely studied. Here, to address this problem, we firstly investigated the effect of the inducer salicylic acid on BaP rhizoremediation, rhizosphere BaP degraders, and PAH degradation-related genes by combining DNA-stable-isotope-probing, high-throughput sequencing, and gene function prediction. BaP removal in the rhizosphere was significantly increased by stimulation with salicylic acid, and the rhizosphere BaP-degrading microbial community structure was significantly changed. Fourteen microbes were responsible for the BaP metabolism, and most degraders, e.g. Aeromicrobium and Myceligenerans, were firstly linked with BaP biodegradation. The enrichment of the PAH-ring hydroxylating dioxygenase (PAH-RHD) gene in the heavy fractions of all 13C-treatments further indicated their involvement in the BaP biodegradation, which was also confirmed by the enrichment of dominant PAH degradation-related genes (e.g. PAH dioxygenase and protocatechuate 3,4-dioxygenase genes) based on gene function prediction. Overall, our study demonstrates that salicylic acid can enhance the rhizosphere BaP biodegradation by altering the community structure of rhizosphere BaP-degrading bacteria and the abundance of PAH degradation-related genes, which provides new insights into BaP rhizoremediation mechanisms in petroleum-contaminated sites.

Haematococcus pluvialis Accumulated Lipid and Astaxanthin in a Moderate and Sustainable Way by the Self-Protection Mechanism of Salicylic Acid Under Sodium Acetate Stress.

To elucidate the mechanism underlying increased fatty acid and astaxanthin accumulation in Haematococcus pluvialis, transcriptome analysis was performed to gain insights into the multiple defensive systems elicited by salicylic acid combined with sodium acetate (SAHS) stresses with a time course. Totally, 112,886 unigenes and 61,323 non-repeat genes were identified, and genes involved in carbon metabolism, primary and secondary metabolism, and immune system responses were identified. The results revealed that SA and NaAC provide both energy and precursors to improve cell growth of H. pluvialis and enhance carbon assimilation, astaxanthin, and fatty acids production in this microalga with an effective mechanism. Interestingly, SA was considered to play an important role in lowering transcriptional activity of the fatty acid and astaxanthin biosynthesis genes through self-protection metabolism in H. pluvialis, leading to its adaption to HS stress and finally avoiding massive cell death. Moreover, positive correlations between 15 key genes involved in astaxanthin and fatty acid biosynthesis pathways were found, revealing cooperative relation between these pathways at the transcription level. These results not only enriched our knowledge of the astaxanthin accumulation mechanism in H. pluvialis but also provided a new view on increasing astaxanthin production in H. pluvialis by a moderate and sustainable way in the future.

Identification of Salicylic Acid Mechanism against Leaf Blight Disease in Oryza sativa by SR-FTIR Microspectroscopic and Docking Studies.

The present study was to investigate the application and mechanism of salicylic acid (SA) as SA-Ricemate for the control of leaf blight disease using a Synchrotron Radiation-based Fourier-Transform Infra-Red (SR-FTIR) microspectroscopy and docking studies. After treating rice plants cv. KDML 105 with SA-Ricemate, the leaves were inoculated with Xanthomonas oryzae pv. oryzae, the causal agent of leaf blight, and disease severity were assessed. The leaves were also used to detect changes in endogenous SA content. The results indicated that SA-Ricemate, as an activated compound, reduced disease severity by 60% at three weeks post-inoculation and increased endogenous content by 50%. The SR-FTIR analysis of changes in the mesophyll of leaves (treated and untreated) showed that the groups of lipids, pectins, and proteins amide I and amide II occurred at higher values, and polysaccharides were shown at lower values in treated compared to untreated. Besides, docking studies were used to model a three-dimensional structure for Pathogenesis-related (PR1b) protein and further identify its interaction with SA. The results showed that ASP28, ARG31, LEU32, GLN97, and ALA93 are important residues that have strong hydrogen bonds with SA. The docking results showed that SA has a good interaction, confirming its role in expression.

Defense Responses of Salicylic Acid in Mango Fruit Against Postharvest Anthracnose, Caused by Colletotrichum gloeosporioides and its Possible Mechanism

AbstractThe effects and mechanisms of salicylic acid (SA) on defense response to Colletotrichum gloeosporioides from mango fruits were investigated by in vitro and in vivo test. In vitro experiment results showed that SA significantly reduced mycelial growth of C. gloeosporioides in a concentration‐dependent manner. SA effectively controlled anthracnose decay on inoculated mango fruit, as well as natural infection. Disease incidence and lesion diameter in SA‐treated fruit were significantly lower than those of the control fruit. SA treatment increased the activities of chitinase, β‐1,3‐glucanase, phenylalanine ammonia‐lyase and polyphenoloxidase, and the content of total phenolic compounds and lignin in mango fruit. Moreover, SA treatment effectively maintained fruit firmness by suppressing conversion of insoluble protopectin into water soluble pectin. And correlation analysis showed there is a higher negative correlation between fruit firmness and disease incidence. These findings suggest that the effect of SA on postharvest diseases was attributed to its direct antimicrobial activity and the elicitation of resistant responses, as well maintaining the firmness in mango fruit. Therefore, SA treatment is a promising measure for controlling postharvest anthracnose rot in mango.Practical ApplicationsInduction of fruit resistance against pathogenic infection with biological or chemical elicitors has been thought to be a promising approach for controlling of postharvest diseases and reducing the use of synthetic fungicides. Anthracnose, caused by Colletotrichum gloeosporioides is the predominant postharvest disease in mango production that causes severe postharvest losses and fruit quality deterioration. SA is a natural plant substance involved in plant defense responses to biotic stresses. The present results from in vitro and in vivo experiment suggested that SA treatment could effectively inhibit mycelial growth of C. gloeosporioides, enhance resistance of mango fruit against the pathogen and reduce anthracnose rot, as well maintain fruit firmness. Hence, SA can be applied in mango storage and preservation.

Direct and indirect inactivation of tumor cell protective catalase by salicylic acid and anthocyanidins reactivates intercellular ROS signaling and allows for synergistic effects.

Salicylic acid and anthocyanidins are known as plant-derived antioxidants, but also can provoke paradoxically seeming prooxidant effects in vitro. These prooxidant effects are connected to the potential of salicylic acid and anthocyanidins to induce apoptosis selectively in tumor cells in vitro and to inhibit tumor growth in animal models. Several epidemiological studies have shown that salicylic acid and its prodrug acetylsalicylic acid are tumor-preventive for humans. The mechanism of salicylic acid- and anthocyanidin-dependent antitumor effects has remained enigmatic so far. Extracellular apoptosis-inducing reactive oxygen species signaling through the NO/peroxynitrite and the HOCl signaling pathway specifically induces apoptosis in transformed cells. Tumor cells have acquired resistance against intercellular reactive oxygen species signaling through expression of membrane-associated catalase. Here, we show that salicylic acid and anthocyanidins inactivate tumor cell protective catalase and thus reactive apoptosis-inducing intercellular reactive oxygen species signaling of tumor cells and the mitochondrial pathway of apoptosis Salicylic acid inhibits catalase directly through its potential to transform compound I of catalase into the inactive compound II. In contrast, anthocyanidins provoke a complex mechanism for catalase inactivation that is initiated by anthocyanidin-mediated inhibition of NO dioxygenase. This allows the formation of extracellular singlet oxygen through the reaction between H(2)O(2) and peroxynitrite, amplification through a caspase8-dependent step and subsequent singlet oxygen-mediated inactivation of catalase. The combination of salicylic acid and anthocyanidins allows for a remarkable synergistic effect in apoptosis induction. This effect may be potentially useful to elaborate novel therapeutic approaches and crucial for the interpretation of epidemiological results related to the antitumor effects of secondary plant compounds.

Control of spot blotch in barley plants with fungicide and Bauhinia variegata Linn. leaf extract

In barley plants (BRS-195), the disease detected as spot blotch is caused by Bipolaris sorokiniana, and is the most deleterious disease for the producers and the beer industry. For fungicides mediated control of this disease can cause risks to environment and human health. To eliminate these drawbacks, one of the methods considered is the use natural products. The purpose of the present study was to investigate the use of extract of leaves from Bauhinia variegata Link. and Opera® fungicide (active ingredient: pyraclostrobin) for controlling Bipolaris sorokiniana in barley plants. In Brazil there are two species of Bauhinia are seen, namely Bauhinia forficata and B. variegate. Extracts from B. variegata didn't show fungitoxic action but B. forficata the action exist. The barley plant showed protection of 92 to 100% in local and systemic action. The chemical TLC assays showed the presence of phenols (rutin, coumaric acid, kaempferol) that can be related to a signal for activation of the defense responses against pathogen or mechanism of salicylic acid. Treatment with fungicide Opera® gave another mechanism and have only 60% of protection.

Tell me more: roles of NPRs in plant immunity

Plants and animals maintain evolutionarily conserved innate immune systems that give rise to durable resistances. Systemic acquired resistance (SAR) confers plant-wide immunity towards a broad spectrum of pathogens. Numerous studies have revealed that NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR) is a key regulator of SAR. Here, we review the mechanisms of NPR1 action in concert with its paralogues NPR3 and NPR4 and other SAR players. We provide insights into the mechanisms of salicylic acid (SA) perception. We discuss the binding of NPR3 and NPR4 with SA that modulates NPR1 coactivator capacity, leading to diverse immune outputs. Finally, we highlight the function of NPR1 as a bona fide SA receptor and propose a possible model of SA perception in planta.

Systemic resistance and growth promotion of chili pepper induced by an antibiotic producing Bacillus vallismortis strain BS07

In the present study, the ability of plant growth-promoting rhizobacterium (PGPR), Bacillus vallismortis strain BS07 (BS07) was evaluated as one of the potential biocontrol agents against multiple pathogens in chili pepper. Under greenhouse conditions, chili pepper seedlings treated with BS07 or chemical control, benzothiadiazole (BTH) by soil drench suppressed the soft rot incidence significantly by reducing the percent disease lesion area per leaf disk compared to negative control. The treatment with BS07 or BTH induced plant resistance against phytophthora blight caused by Phytophthora capsici upon pathogen challenge. There was a greater reduction of anthracnose infection caused by Colletotrichum acutatum on matured fruits in BS07 or BTH treated plants when compared to untreated control. Under field conditions, percent of soft rot incidence and disease severity of phytophthora blight were significantly reduced in BS07 and BTH treated plants when compared to untreated control. In the case of anthracnose disease, the significant reduction of disease was observed during the two years on matured fruits, when compared to untreated control. The study also clearly showed that there was a significant increase of fruit yield in BS07 treated plants, and it has also been observed that BS07 treated plants showed higher chlorophyll content in the fresh leaves compared to untreated control. Reverse transcriptase (RT)-PCR analyses of Arabidopsis thaliana leaves revealed up-regulation of PR1a gene expression in Col-0, while there was no expression in Nag-G plants treated with BS07 suspensions. This suggests that the systemic resistance might be evolved by the mechanism of salicylic acid (SA) dependent pathway.

Photoionization and Photoexcitation Mechanisms of Salicylic Acid

Salicylic acid(SA),the active ingredient of aspirin,is effective in various medical treatments such as cosmetology and anticancer therapy.We investigated the photophysical and photochemical behavior of SA using 266 nm laser flash photolysis.Results demonstrate that SA can be photoionized and photoexcited by 266 nm photons to give SA+ and 3SA*.SA is highly photosensitive and can be photoionized via a monophotonic process with a quantum yield of 0.21.Under the aerobic conditions we find that in cells,hydrated electrons easily combine with oxygen to generate O-20,which can kill cancer cells.SA+ can be converted into neutral radicals by deprotonation and its pKa value is 2.95.SA also can be oxidized by SO-40 and the rate constant is 2.28×109 L.mol-1.s-1,which further confirms the photoionization ability of SA.In addition,SA can be excited to 3SA*,which then generates 1O2*.This research provides introductory theory for the potential of SA to be used as an anticancer drug.

Electric field assisted transdermal drug delivery from salicylic acid-loaded polyacrylamide hydrogels

The apparent diffusion coefficients, Dapp, and the release mechanisms of salicylic acid from polyacrylamide hydrogels through pigskin were investigated. Dapp increases with increasing electric field strength and reaches the maximum value at electric field strength of 0.1 V; beyond that it decreases with increasing electric field strength and becomes saturated at 5 V. The increase in Dapp at low electric field strength can be attributed to the combination of iontophoresis, electroporation of matrix pore, and induced pathway in pigskin. Dapp obeys the scaling behavior Dapp/Do = (drug size/pore size)m with m equal to 0.67 and 0.49 at the electric field strengths of 0 and 0.1 V, respectively.

Salicylic acid blocks indomethacin-induced cyclooxygenase inhibition and lesion formation in rat gastric mucosa.

Salicylic acid has been shown to decrease gastric mucosal lesions induced by indomethacin in the rat. In vitro, it has also been shown to counteract the inhibitory effect of indomethacin and aspirin on the cyclooxygenase enzyme system in seminal vesicle microsomes and in platelets and vascular tissue. The hypothesis that the mechanism of salicylic acid "protection" against indomethacin-induced gastric lesions involves interference with indomethacin-induced mucosal cyclooxygenase inhibition was tested. Male, fasted rats were treated with intragastric salicylic acid in doses of 50, 100, 200, 300, or 400 mg/kg concomitantly with a sc injection of 20 mg/kg of indomethacin. Gastric mucosal lesions and mucosal cyclooxygenase activity (as measured by ex vivo prostaglandin F2 alpha synthesis) were examined 3 hr later. Intragastric salicylic acid, 200-400 mg/kg, significantly reduced indomethacin-induced lesion formation, while counteracting significantly indomethacin inhibition of prostaglandin synthesis. Salicylic acid alone did not significantly change cyclooxygenase activity. It is concluded that topical salicylic acid can decrease indomethacin-induced gastric mucosal lesion in the rat, in part, by counteracting the inhibitory effect of indomethacin at the cyclooxygenase level.