Antifungal properties of haem peroxidase from Acorus calamus

Antibacterial Action of Protein Fraction Isolated from Rapana venosa Hemolymph against Escherichia coli NBIMCC 8785

Natural products and especially those from marine organisms are being intensively explored as an alternative to synthetic antibiotics. However, the exact mechanisms of their action are not yet well understood. The molecular masses of components in the hemolymph fraction with MW 50-100 kDa from Rapana venosa were determined using ImageQuant™ TL v8.2.0 software based on electrophoretic analysis. Mainly, three types of compounds with antibacterial potential were identified, namely proteins with MW at 50.230 kDa, 62.100 kDa and 93.088 kDa that were homologous to peroxidase-like protein, aplicyanin A and L-amino acid oxidase and functional units with MW 50 kDa from R. venous hemocyanin. Data for their antibacterial effect on Escherichia coli NBIMCC 8785 were obtained by CTC/DAPI-based fluorescent analysis (analysis based on the use of a functional fluorescence probe). The fluorescent analyses demonstrated that a 50% concentration of the fraction with MW 50-100 kDa was able to eliminate 99% of the live bacteria. The antimicrobial effect was detectable even at a 1% concentration of the active compounds. The bacteria in this case had reduced metabolic activity and a 24% decreased size. The fraction had superior action compared with another mollusc product-snail slime-which killed 60% of the E. coli NBIMCC 8785 cells at a 50% concentration and had no effect at a 1% concentration. The obtained results demonstrate the high potential of the fraction with MW 50-100 kDa from R. venosa to eliminate and suppress the development of Escherichia coli NBIMCC 8785 bacteria and could be applied as an appropriate component of therapeutics with the potential to replace antibiotics to avoid the development of antibiotic resistance.

In Vitro Antibacterial Activity of Green Synthesized Silver Nanoparticles Using Mangifera indica Aqueous Leaf Extract against Multidrug-Resistant Pathogens

An estimated 35% of the world’s population depends on wheat as their primary crop. One fifth of the world’s wheat is utilized as animal feed, while more than two thirds are used for human consumption. Each year, 17–18% of the world’s wheat is consumed by China and India. In wheat, spot blotch caused by Bipolaris sorokiniana is one of the major diseases which affects the wheat crop growth and yield in warmer and humid regions of the world. The present work was conducted to evaluate the effect of green synthesized silver nanoparticles on the biochemical constituents of wheat crops infected with spot blotch disease. Silver nanoparticles (AgNPs) were synthesized using Mangifera indica leaf extract and their characterization was performed using UV-visible spectroscopy, SEM, XRD, and PSA. Characterization techniques confirm the presence of crystalline, spherical silver nanoparticles with an average size of 52 nm. The effect of green synthesized nanoparticles on antioxidative enzymes, e.g., Superoxide dismutase (SOD), Catalase (CAT), Glutathione Reductase (GR), Peroxidase (POX), and phytochemical precursor enzyme Phenylalanine Ammonia-Lyase (PAL), and on primary and secondary metabolites, e.g., reducing sugar and total phenol, in Bipolaris sorokiniana infected wheat crop were studied. Inoculation of fungal spores was conducted after 40 days of sowing. Subsequently, diseased plants were treated with silver nanoparticles at different concentrations. Elevation in all biochemical constituents was recorded under silver nanoparticle application. The treatment with a concentration of nanoparticles at 50 pp min diseased plants showed the highest resistance towards the pathogen. The efficacy of the green synthesized AgNPs as antibacterial agents was evaluated against multi drug resistant (MDR) bacteria comprising Gram-negative bacteria Escherichia coli (n = 6) and Klebsiella pneumoniae (n = 7) and Gram-positive bacteria Methicillin resistant Staphylococcus aureus (n = 2). The results show promising antibacterial activity with significant inhibition zones observed with the disc diffusion method, thus indicating green synthesized M. indica AgNPs as an active antibacterial agent against MDR pathogens.

Performance of Novel Antimicrobial Protein Bg_9562 and In Silico Predictions on Its Properties with Reference to Its Antimicrobial Efficiency against Rhizoctonia solani

Bg_9562 is a potential broad-spectrum antifungal effector protein derived from the bacteria Burkholderia gladioli strain NGJ1 and is effective against Rhizoctonia solani, the causal agent of sheath blight in rice. In the present study, in vitro antifungal assays showed that Bg_9562 was efficient at 35 °C and 45 °C and ineffective either at high acidic pH (3.0) or alkaline pH (9.5) conditions. Compatibility studies between the native bioagents Trichoderma asperellum TAIK1 and Bacillus subtilis BIK3 indicated that Bg_9562 was compatible with the bioagents. A field study using foliar spray of the Bg_9562 protein indicated the need of formulating the protein before its application. In silico analysis predicted that Bg_9562 possess 111 amino acid residues (46 hydrophobic residues, 12 positive and 8 negative residues) with the high aliphatic index of 89.92, attributing to its thermostability with a half-life of 30 h. Bg_9562 (C491H813N137O166S5) possessed a protein binding potential of 1.27 kcal/mol with a better possibility of interacting and perturbing the membrane, the main target for antimicrobial proteins. The secondary structure revealed the predominance of random coils in its structure, and the best 3D model of Bg_9562 was predicted using an ab initio method with Robetta and AlphaFold 2. The predicted binding ligands were nucleic acids and zinc with confidence scores of 0.07 and 0.05, respectively. The N-terminal region (1-14 residues) and C-terminal region (101 to 111) of Bg_9562 residues were predicted to be disordered regions. Stability and binding properties of the protein from the above studies would help to encapsulate Bg_9562 using a suitable carrier to maintain efficiency and improve delivery against Rhizoctonia solani in the most challenging rice ecosphere.

Integrating host immune status, Labyrinthula spp. load and environmental stress in a seagrass pathosystem: Assessing immune markers and scope of a new qPCR primer set

Recent trends suggest that marine disease outbreaks caused by opportunistic pathogens are increasing in frequency and severity. One such malady is seagrass wasting disease, caused by pathogens in the genus Labyrinthula. It is suspected that pathogenicity is intimately linked to the ability of the host to initiate defense responses; however, supportive evidence is lacking. To address this, we developed two techniques, including 1) a new qPCR-based pathogen detection method, and 2) an immune profiling panel via four host-biomarker assays (measuring peroxidase, exochitinase, polyphenol oxidase, and lysozyme activities). These techniques were then used to experimentally investigate the impact of environmental stressors (namely, elevated temperature and salinity) on host immunity and how immune status might affect susceptibility to Labyrinthula infection. In the first experiment, we subjected individual turtlegrass (Thalassia testudinum) shoots to short-term (7 d) abiotic stressors alone. In a second experiment, the same abiotic stressor conditions were followed by pathogen exposure (7 additional d), simulating a scenario where we attempt to isolate the impact of environmental stressors on the host seagrass species by removing the stressor as the pathogen is introduced. The qPCR assay successfully quantified the abundance of Labyrinthula spp. cells from both pure cultures and seagrass tissues across a broad range of predominately pathogenic strains, with high sensitivity. Immune enzyme assays revealed that all four biomarkers were constitutively active in turtlegrass individuals, but specific activities were largely unaffected by the chosen abiotic stressor conditions. We also identified positive correlations between pathogen load and two biomarkers (peroxidase, exochitinase), regardless of abiotic stress treatment, further demonstrating the potential utility of these biomarkers in future applications.

A Gene Regulatory Network Controlled by BpERF2 and BpMYB102 in Birch under Drought Conditions

Gene expression profiles are powerful tools for investigating mechanisms of plant stress tolerance. Betula platyphylla (birch) is a widely distributed tree, but its drought-tolerance mechanism has been little studied. Using RNA-Seq, we identified 2917 birch genes involved in its response to drought stress. These drought-responsive genes include the late embryogenesis abundant (LEA) family, heat shock protein (HSP) family, water shortage-related and ROS-scavenging proteins, and many transcription factors (TFs). Among the drought-induced TFs, the ethylene responsive factor (ERF) and myeloblastosis oncogene (MYB) families were the most abundant. BpERF2 and BpMYB102, which were strongly induced by drought and had high transcription levels, were selected to study their regulatory networks. BpERF2 and BpMYB102 both played roles in enhancing drought tolerance in birch. Chromatin immunoprecipitation combined with qRT-PCR indicated that BpERF2 regulated genes such as those in the LEA and HSP families, while BpMYB102 regulated genes such as Pathogenesis-related Protein 1 (PRP1) and 4-Coumarate:Coenzyme A Ligase 10 (4CL10). Multiple genes were regulated by both BpERF2 and BpMYB102. We further characterized the function of some of these genes, and the genes that encode Root Primordium Defective 1 (RPD1), PRP1, 4CL10, LEA1, SOD5, and HSPs were found to be involved in drought tolerance. Therefore, our results suggest that BpERF2 and BpMYB102 serve as transcription factors that regulate a series of drought-tolerance genes in B. platyphylla to improve drought tolerance.

Bioactive potential of Indian stinging plants leaf extract against pathogenic fungi

Background & methods We investigated the in vitro antioxidant and antifungal activity by agar disc diffusion assay of leaf extract of some stinging plants namely, Urtica dioica L., Tragia involucrate L., Carduus nutans L. and Mucuna pruriens (L.) DC., against pathogenic fungi causing infections/diseases. Results M. pruriens (Disc 4), T. involucrate (Disc 2), U. dioica (Disc 1) showed significant antifungal activity against all tested pathogens, while C. nutans (Disc 3) showed intermediate activity against only Chaetomium globosum (Cg). The leaf extract of M. Pruriens showed maximum total phenol content (~1004 µg g-1 dry wt) followed by T. involucrate, C. nutans and U. dioica. However, the ascorbate was observed highest in T. involucrate (~10.3 µg g-1 dry wt) followed by M. pruriens (~9.2 µg g-1 dry wt) but the difference was not significant (p ≤ 0.05). Likewise, M. pruriens showed maximum anthocyanin content (~0.3 µg g-1 dry wt). The activity of antioxidant enzymes revealed that M. Pruriens showed maximum ascorbate peroxidase (APX) activity, while the highest guaiacol peroxidase (GPX) and catalase (CAT) activities were observed in C. nutans and U. dioica, respectively. Conclusions M. Pruriens showed potential in vitro antioxidant and antifungal activity against studied pathogens that may be used for ethno-pharmacological uses.

A novel peroxidase purified from Marsdenia megalantha latex inhibits phytopathogenic fungi mediated by cell membrane permeabilization

An antifungal class III peroxidase was purified from Marsdenia megalantha latex (named Mo-POX) using DEAE-cellulose and gel filtration chromatography on a Superose 12 HR 10/30 column. Mm-POX has an apparent molecular mass of 67.0kDa and a pI of 5.2, shares identity with other peroxidases, and follows Michaelis-Menten kinetics. It has a high affinity for guaiacol and hydrogen peroxide. The pH and temperature optima for Mm-POX were 5.0-7.0 and 60°C, respectively. The catalytic activity of Mm-POX was decreased in the presence of classic peroxidase inhibitors including azide, dithiothreitol, ethylenediamine tetraacetic acid, and sodium metabisulfite and high concentrations of Na⁺, Mn⁺, and salicylic acid. In contrast, Ca⁺ and Mg⁺, even at low concentrations, enhanced the Mm-POX enzymatic activity. This protein inhibited the germination of the conidia of the phytopathogenic fungi Fusarium oxysporum and Fusarium solani by acting through a membrane permeabilization mechanism. Mm-POX also induced oxidative stress in F. solani. Mm-POX is the first enzyme to be isolated from the M. megalantha species and it has potential use in the control of plant disease caused by important phytopathogenic fungi. This adds biotechnological value to this enzyme.

Anti-oxidant and anti-microbial properties of some ethno-therapeutically important medicinal plants of Indian Himalayan Region

Therapeutic potential of medicinal plants as a source of noble natural anti-oxidants and anti-microbial agents has been well recognised all across the globe. In this study, phenolic compounds, in vitro anti-oxidant activity and anti-microbial properties have been investigated in five Himalayan medicinal plants, (e.g., Acorus calamus, Habenaria intermedia, Hedychium spicatum, Roscoea procera and Valeriana jatamansi) in different solvent systems. R. procera exhibited significantly (p < 0.05) higher phenolics; while H. spicatum was rich in flavonoids and V. jatamansi in anti-oxidant activity. Also, R. procera and H. spicatum were found rich in gallic acid; V. jatamansi in catechin, hydroxylbenzoic acid and caffeic acid and H. intermedia in hydroxyl benzoic acid. Solvent systems showed species specific response for extraction of total flavonoids and anti-oxidant activity. All the extracts were found effective against different bacterial and fungal strains in a dose dependent manner and maximum antimicrobial activity was found in R. procera as compared to other species. All the plant extracts showed greater activity against bacterial strains as compared to fungal strains. The results of this study suggest that extract of these species can be used as natural anti-oxidant to reduce free radical mediated disorders and as natural alternative for food preservation.

Transcriptome and proteome analyses provide insight into laticifer's defense of Euphorbia tirucalli against pests

The cytoplasm of laticifers, which are plant cells specialized for rubber production and defense against microbes and herbivores, is a latex. Although laticifers share common functions, the protein constituents of latexes are highly variable among plant species and even among organs. In this study, transcriptomic and proteomic analyses of Euphorbia tirucalli's (Euphorbiaceae) latex were conducted to determine the molecular basis of the laticifer's functions in this plant. The hybrid de novo assembly of Illumina mRNA-seq and expressed sequence tags obtained by Sanger's sequencing revealed 26,447 unigenes. A unigene similar to Arabidopsis embryo-specific protein 3 (AT5G62200), which is a PLAT domain-containing protein, and rubber elongation factor showed the highest expression levels. The proteome analysis, studied by liquid chromatography-mass spectrometry with the de novo assembled unigenes as the database, revealed 161 proteins in the latex, 107 of which were not detected in the stem. A gene ontology analysis indicated that the laticifer's proteome was enriched with proteins related to proteolysis, phosphatase, defense against various environmental stresses and lipid metabolisms. D-mannose-binding lectin, ricin (which lacked the N-terminal conserved ribosome-inactivating protein domain), chitinase and peroxidase were highly accumulated, as confirmed by two-dimensional polyacrylamide gel electrophoresis. Thus, the lectins and chitinase may be the major defensive proteins against pests, and the other defense-related proteins and transcripts detected in latex may work in coordination with them. Highly expressing unigenes with unknown functions are candidate novel defense- or rubber production-related genes.

Friends or foes? Emerging insights from fungal interactions with plants

Fungi interact with plants in various ways, with each interaction giving rise to different alterations in both partners. While fungal pathogens have detrimental effects on plant physiology, mutualistic fungi augment host defence responses to pathogens and/or improve plant nutrient uptake. Tropic growth towards plant roots or stomata, mediated by chemical and topographical signals, has been described for several fungi, with evidence of species-specific signals and sensing mechanisms. Fungal partners secrete bioactive molecules such as small peptide effectors, enzymes and secondary metabolites which facilitate colonization and contribute to both symbiotic and pathogenic relationships. There has been tremendous advancement in fungal molecular biology, omics sciences and microscopy in recent years, opening up new possibilities for the identification of key molecular mechanisms in plant-fungal interactions, the power of which is often borne out in their combination. Our fragmentary knowledge on the interactions between plants and fungi must be made whole to understand the potential of fungi in preventing plant diseases, improving plant productivity and understanding ecosystem stability. Here, we review innovative methods and the associated new insights into plant-fungal interactions.

Plant antifungal proteins and their applications in agriculture

Fungi are far more complex organisms than viruses or bacteria and can develop numerous diseases in plants that cause loss of a substantial portion of the crop every year. Plants have developed various mechanisms to defend themselves against these fungi which include the production of low-molecular-weight secondary metabolites and proteins and peptides with antifungal activity. In this review, families of plant antifungal proteins (AFPs) including defensins, lectins, and several others will be summarized. Moreover, the application of AFPs in agriculture will also be analyzed.

The effect on the transcriptome of Anemone coronaria following infection with rust (Tranzschelia discolor)

In order to understand plant/pathogen interaction, the transcriptome of uninfected (1S) and infected (2I) plant was sequenced at 3'end by the GS FLX 454 platform. De novo assembly of high-quality reads generated 27,231 contigs leaving 37,191 singletons in the 1S and 38,393 in the 2I libraries. ESTcalc tool suggested that 71% of the transcriptome had been captured, with 99% of the genes present being represented by at least one read. Unigene annotation showed that 50.5% of the predicted translation products shared significant homology with protein sequences in GenBank. In all 253 differential transcript abundance (DTAs) were in higher abundance and 52 in lower abundance in the 2I library. 128 higher abundance DTA genes were of fungal origin and 49 were clearly plant sequences. A tBLASTn-based search of the sequences using as query the full length predicted polypeptide product of 50 R genes identified 16 R gene products. Only one R gene (PGIP) was up-regulated. The response of the plant to fungal invasion included the up-regulation of several pathogenesis related protein (PR) genes involved in JA signaling and other genes associated with defense response and down regulation of cell wall associated genes, non-race-specific disease resistance1 (NDR1) and other genes like myb, presqualene diphosphate phosphatase (PSDPase), a UDP-glycosyltransferase 74E2-like (UGT). The DTA genes identified here should provide a basis for understanding the A. coronaria/T. discolor interaction and leads for biotechnology-based disease resistance breeding.

Allelic diversity in the transcriptomes of contrasting rust-infected genotypes of Lathyrus sativus, a lasting resource for smart breeding

BACKGROUND

Grass pea (Lathyrus sativus L.) is a valuable resource for potentially durable partial resistance to rust. To gain insight into the resistance mechanism and identify potential resistance genes, we generated the first comprehensive transcriptome assemblies from control and Uromyces pisi inoculated leafs of a susceptible and a partially rust-resistant grass pea genotype by RNA-seq.

RESULTS

134,914 contigs, shared by both libraries, were used to analyse their differential expression in response to rust infection. Functional annotation grouped 60.4% of the contigs present in plant databases (37.8% of total) to 33 main functional categories, being "protein", "RNA", "signalling", "transport" and "stress" the most represented. Transcription profiles revealed considerable differences in regulation of major phytohormone signalling pathways: whereas Salicylic and Abscisic Acid pathways were up-regulated in the resistant genotype, Jasmonate and Ethylene pathways were down-regulated in the susceptible one. As potential Resistance-genes we identified a mildew resistance locus O (MLO)-like gene, and MLO-related transcripts. Also, several pathogenesis-related genes were up-regulated in the resistant and exclusively down regulated in the susceptible genotype. Pathogen effectors identified in both inoculated libraries, as e.g. the rust Rtp1 transcript, may be responsible for the down-regulation of defence-related transcripts. The two genotypes contained 4,892 polymorphic contigs with SNPs unevenly distributed between different functional categories. Protein degradation (29.7%) and signalling receptor kinases (8.2%) were the most diverged, illustrating evolutionary adaptation of grass pea to the host/pathogens arms race.

CONCLUSIONS

The vast array of novel, resistance-related genomic information we present here provides a highly valuable resource for future smart breeding approaches in this hitherto under-researched, valuable legume crop.

The pathogenesis-related protein PR-4b from Theobroma cacao presents RNase activity, Ca(2+) and Mg(2+) dependent-DNase activity and antifungal action on Moniliophthora perniciosa

BACKGROUND

The production and accumulation of pathogenesis-related proteins (PR proteins) in plants in response to biotic or abiotic stresses is well known and is considered as a crucial mechanism for plant defense. A pathogenesis-related protein 4 cDNA was identified from a cacao-Moniliophthora perniciosa interaction cDNA library and named TcPR-4b.

RESULTS

TcPR-4b presents a Barwin domain with six conserved cysteine residues, but lacks the chitin-binding site. Molecular modeling of TcPR-4b confirmed the importance of the cysteine residues to maintain the protein structure, and of several conserved amino acids for the catalytic activity. In the cacao genome, TcPR-4b belonged to a small multigene family organized mainly on chromosome 5. TcPR-4b RT-qPCR analysis in resistant and susceptible cacao plants infected by M. perniciosa showed an increase of expression at 48 hours after infection (hai) in both cacao genotypes. After the initial stage (24-72 hai), the TcPR-4b expression was observed at all times in the resistant genotypes, while in the susceptible one the expression was concentrated at the final stages of infection (45-90 days after infection). The recombinant TcPR-4b protein showed RNase, and bivalent ions dependent-DNase activity, but no chitinase activity. Moreover, TcPR-4b presented antifungal action against M. perniciosa, and the reduction of M. perniciosa survival was related to ROS production in fungal hyphae.

CONCLUSION

To our knowledge, this is the first report of a PR-4 showing simultaneously RNase, DNase and antifungal properties, but no chitinase activity. Moreover, we showed that the antifungal activity of TcPR-4b is directly related to RNase function. In cacao, TcPR-4b nuclease activities may be related to the establishment and maintenance of resistance, and to the PCD mechanism, in resistant and susceptible cacao genotypes, respectively.

Isolation and in-silico characterization of Peroxidase isoenzymes from Wheat (Triticum aestivum) against Karnal Bunt (Tilletia indica)

To investigate the role of Peroxidase and its physiological significance under Karnal Bunt (KB) were determined in resistant (HD-29) and susceptible genotype (WH-542) of wheat during different developmental stages. The enzymes were expressed constitutively in both the susceptible and resistant genotype. In gel assay and differential expression analysis of POD was significantly higher (p >0.05) in Sv and S2, than the S1 and S3 stages. in silico analysis of Peroxidase for eg. physico-chemical properties, secondary structural features and phylogenetic classification for comparative analysis. Motif and Domain analysis of Peroxidase by MEME, to be important for the biological functions, and studies of evolution. Our results clearly indicate that the enhanced expression of POD at the WS2 stage, which reinforces its role in stage dependent immunity against Karnal bunt and role of POD metabolism provides genotype and stage dependant structural barrier resistance in wheat against KB.

An overview on traditional uses and pharmacological profile of Acorus calamus Linn. (Sweet flag) and other Acorus species

Acorus calamus (Sweet flag) has a long history of use and has numerous traditional and ethnomedicinal applications. Since ancient times, it has been used in various systems of medicines such as Ayurveda, Unani, Siddha, Chinese medicine, etc. for the treatment of various aliments like nervous disorders, appetite loss, bronchitis, chest pain, colic, cramps, diarrhea, digestive disorders, flatulence, gas, indigestion, rheumatism, sedative, cough, fever, bronchitis, inflammation, depression, tumors, hemorrhoids, skin diseases, numbness, general debility and vascular disorders. Various therapeutic potentials of this plant have been attributed to its rhizome. A number of active constituents from leaves, rhizomes and essential oils of A. calamus have been isolated and characterized. Of the constituents, alpha and beta-asarone are the predominant bioactive components. Various pharmacological activities of A. calamus rhizome such as sedative, CNS depressant, anticonvulsant, antispasmodic, cardiovascular, hypolipidemic, immunosuppressive, anti-inflammatory, cryoprotective, antioxidant, antidiarrheal, antimicrobial, anticancer and antidiabetic has been reported. Genotoxicity and mutagenecity of beta and alpha-asarone is reported, which limits their use at high dosage. Though A. calamus has been used since ancient times, many of its uses are yet to be scientifically validated. In the present review an attempt has been made to explore traditional uses and pharmacological properties of A. calamus.

Activation of Defense Mechanisms against Pathogens in Mosses and Flowering Plants

During evolution, plants have developed mechanisms to cope with and adapt to different types of stress, including microbial infection. Once the stress is sensed, signaling pathways are activated, leading to the induced expression of genes with different roles in defense. Mosses (Bryophytes) are non-vascular plants that diverged from flowering plants more than 450 million years ago, allowing comparative studies of the evolution of defense-related genes and defensive metabolites produced after microbial infection. The ancestral position among land plants, the sequenced genome and the feasibility of generating targeted knock-out mutants by homologous recombination has made the moss Physcomitrella patens an attractive model to perform functional studies of plant genes involved in stress responses. This paper reviews the current knowledge of inducible defense mechanisms in P. patens and compares them to those activated in flowering plants after pathogen assault, including the reinforcement of the cell wall, ROS production, programmed cell death, activation of defense genes and synthesis of secondary metabolites and defense hormones. The knowledge generated in P. patens together with comparative studies in flowering plants will help to identify key components in plant defense responses and to design novel strategies to enhance resistance to biotic stress.

Neuroprotective effect of saponin rich extract of Acorus calamus L. in rat model of chronic constriction injury (CCI) of sciatic nerve-induced neuropathic pain

ETHNOPHARMACOLOGICAL RELEVANCE

Traditionally, Acorus calamus has been used for the treatment and management of headache, migraine, body ache and severe inflammatory pain in the Unani, Ayurveda and Indian system of medicine.

AIM OF THE STUDY

Present study focuses on the evaluation of saponin rich extract of Acorus calamus (SRE-AC) in chronic constriction injury (CCI) of sciatic nerve induced neuropathic pain and neuronal functional changes in rats.

MATERIALS AND METHODS

The pain sensitive tests, i.e., thermal and mechanical hyperalgesia and sciatic functional index test, were performed on the different days, i.e., days 0, 1, 7, 14, and 21. The motor and sensory nerve conduction velocity was also measured on the 21st day. Tissue total protein, superoxide anion generation, total calcium, myeloperoxidase and TNF-α levels were estimated to assess biochemical changes. Histopathological evaluations were also performed. SRE-AC (20 and 40 mg/kg) and pregabalin (10mg/kg, serving as a positive control) were administered orally for 14 consecutive days from the day of surgery.

RESULTS

CCI produced significant (P<0.05) increase in thermal and mechanical hyperalgesia, rise in sciatic functional index, decrease in nerve conduction velocity, along with biochemical and histopathological changes. Oral administration of SRE-AC and pregabalin significantly (P<0.05) ameliorated CCI-induced nociceptive pain threshold, sciatic functional and electrophysiological changes in a dose dependent manner. Further, tissue biochemical and histopathological changes were also attenuated.

CONCLUSION

SRE-AC has shown ameliorative effect in CCI-induced neuropathic pain which may be attributed to its multiple actions including anti-oxidative, anti-inflammatory and neuroprotective actions.

The synthetic strigolactone GR24 influences the growth pattern of phytopathogenic fungi

Strigolactones that are released by plant roots to the rhizosphere are involved in both plant symbiosis with arbuscular mycorrhizal fungi and in plant infection by root parasitic plants. In this paper, we describe the response of various phytopathogenic fungi to the synthetic strigolactone GR24. When GR24 was embedded in the growth medium, it inhibited the growth of the root pathogens Fusarium oxysporum f. sp. melonis, Fusarium solani f. sp. mango, Sclerotinia sclerotiorum and Macrophomina phaseolina, and of the foliar pathogens Alternaria alternata, Colletotrichum acutatum and Botrytis cinerea. In the presence of this synthetic strigolactone, intense branching activity was exhibited by S. sclerotiorum, C. acutatum and F. oxysporum f. sp. melonis. Slightly increased hyphal branching was observed for A. alternata, F. solani f. sp. mango and B. cinerea, whereas suppression of hyphal branching by GR24 was observed in M. phaseolina. These results suggest that strigolactones not only affect mycorrhizal fungi and parasitic plants, but they also have a more general effect on phytopathogenic fungi.

Terpenoid composition and antifungal activity of three commercially important essential oils against Aspergillus flavus and Aspergillus niger

Hydro-distilled essential oils extracted from three commercially important aromatic plants were analysed by capillary gas chromatography-flame ionization detector and gas chromatography/quadrupole mass spectrometry and subjected to antifungal activity. Fifteen compounds, which accounted for 97.8% of Acorus calamus root oil composition have been identified. Besides the major constituent (Z)-asarone (81.1-92.4%), (Z)-methyl isoeugenol (1.8-2.1%), (Z)-isoelemicin (1.2-1.3%), (E)-asarone (1.0-2.6%), (E)-methyl isoeugenol (0.2-0.4%), (Z)-β-ocimene (0.2-0.4%), elemicin (0.2-0.3%), linalool (0.1-0.9%) and kessane (t-0.2%) were identified. Monoterpenes constituted the main fraction of Origanum vulgare essential oil attaining 90.5% of the total oil composition. p-Cymene (10.3%) was the major component of the monoterpene hydrocarbon fraction while thymol (53.2%) and carvacrol (3.9%) were the most abundant oxygenated monoterpenes among the 33 identified constituents. Cinnamomum tamala leaf oil contained (E)-cinnamaldehyde as the principal component. Quantitative variations in (Z)-cinnamaldehyde (5.8-7.1%), linalool (6.4-8.5%) and (E)-cinnamyl acetate (4.7-5.2%) were significant. The antifungal activity of the hydro-distilled essential oils of A. calamus, O. vulgare and C. tamala were evaluated against Aspergillus flavus and Aspergillus niger. Disc diffusion method was used for the determination of the inhibitory effect. O. vulgare essential oil exhibited the highest activity. Moreover, all three essential oils inhibit the growth of A. flavus and A. niger.

Structural-functional features of plant isoperoxidases

Current data on structural--functional features of plant peroxidases and their involvement in functioning of the pro-/antioxidant system responding to stress factors, especially those of biotic origin, are analyzed. The collection of specific features of individual isoforms allows a plant to withstand an aggressive influence of the environment. Expression of some genes encoding different isoperoxidases is regulated by pathogens (and their metabolites), elicitors, and hormone-like compounds; specific features of this regulation are considered in detail. It is suggested that isoperoxidases interacting with polysaccharides are responsible for a directed deposition of lignin on the cell walls, and this lignin in turn is concurrently an efficient strengthening material and protects the plants against pathogens.

Implementation of bio-fungicides and seed treatment in organic rice cv. KDML 105 farming

This study was aimed to evaluate the several chemical compounds of relatively composite structure with antifungal activity from Thai local medical plants. The antifungal activity of Stemona curtisii HK. f., Stemona tuberose L., Acorus calamus L., Eugenia caryophyllus, Memmea siamensis Kost. and an eugenol active compound were studied in vitro. Four pathogenic seed borne fungi, Alternaria solani, Colletotrichum sp., Fusarium moniliforme and Rhizoctonia solani were used as target organisms. The agar overlay technique and spore inhibition techniques were applied for the determination of their essential oil and active compound antifungal activity at various concentration; 0.10, 0.25, 0.50 and 1.00% (v/v) and untreated as control (0% v/v). Eugenol active compound showed the strongest antifungal activity on all species of tested fungal species. On the other hand, the antifungal activity of those bio-fungicides was lined up into a series from strong to low, as follows: Eugenia caryophyllus > Acorus calamus Linn. > Stemona tuberosa L. > Stemona curtisii Hk.f, while Mammea siamensis Kost. could not control any fungal species. Moreover, after eugenol application, lysis of spore and inhibition of mycelium growth were detected. Microscopic analysis exhibited complete lysis of spores after 24 h at a concentration of 1.00% v/v. Moreover, at the same concentration and 96 h incubation the mycelia growth was completely inhibited.

Quickly-released peroxidase of moss in defense against fungal invaders

Mosses (Bryophyta) are nonvascular plants that constitute a large part of the photosynthesizing biomass and carbon storage on Earth. Little is known about how this important portion of flora maintains its health status. This study assessed whether the moss, Physcomitrella patens, responds to treatment with chitosan, a fungal cell wall-derived compound inducing defense against fungal pathogens in vascular plants. Application of chitosan to liquid culture of P. patens caused a rapid increase in peroxidase activity in the medium. For identification of the peroxidase(s), matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF)/MS, other methods and the whole-genome sequence of P. patens were utilized. Peroxidase gene knock-out mutants were made and inoculated with fungi. The peroxidase activity resulted from a single secreted class III peroxidase (Prx34) which belonged to a P. patens specific phylogenetic cluster in analysis of the 45 putative class III peroxidases of P. patens and those of Arabidopsis and rice. Saprophytic and pathogenic fungi isolated from another moss killed the Prx34 knockout mutants but did not damage wild-type P. patens. The data point out the first specific host factor that is pivotal for pathogen defense in a nonvascular plant. Furthermore, results provide conclusive evidence that class III peroxidases in plants are needed in defense against hostile invasion by fungi.