Browsing by Author "Pawan K. Singh"

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Anticancer compounds from cyanobacterium Lyngbya species: A review
(Kluwer Academic Publishers, 2015) Shasank S. Swain; Rabindra N. Padhy; Pawan K. Singh
The use of synthetic anticancer drugs and other methods followed in cancer therapy have several side effects; and ineffective methods or drugs give a way to the emergence of drug resistant cancer cells, with the intrinsic metastasis as the aftermath. Anticancer efficacy of many cyanobacterial compounds has been claimed in literature. This review considers 144 compounds isolated and characterized from seven species of the non-nitrogen fixing filamentous cyanobacterium Lyngbya, as the source of antineoplastic agents, which have been screened primarily with cancer cell lines. Structure and information of Lyngbya compounds were retrieved from databases, PubChem, ChemSpider and ChEBI. Information and clinical status of Lyngbya compounds are summarized, and those might be the future anticancer drugs for drug-resistant cancer cells even, as complementary/ adduct drugs, if pursued thoroughly in pharmacology and pharmaceutics. © Springer International Publishing Switzerland 2015.
Characterization of the Biocidal Spectrum of Extracellular Filtrates of Microcystis aeruginosa
(2011) Pranita Jaiswal; Radha Prasanna; Pawan K. Singh
The effect of dichloromethane (DCM) and ethyl acetate (EA) extract of a cyanobacterium, Microcystis aeruginosa was evaluated against unicellular cyanobacteria and the phytopathogenic fungus Rhizoctonia solani. Fractionation of the filtrate showed the presence of five spots of different Rf values on silica gel coated plates indicating the presence of a number of compounds in the extract. A marked reduction in growth (52%) of the fungus was recorded on the plates supplemented with cyanobacterial extract, indicating the involvement of anti-fungal metabolite(s). The extract did not show any negative influence on seed germination and growth of seedlings of wheat, rice and mung, emphasizing the suitability of the compound for use in agriculture. © 2011 Association of Microbiologists of India.
Computational approach for locating effective cyanobacterial compounds against Mycobacterium tuberculosis
(Association of Pharmaceutical Teachers of India, 2017) Shasank S. Swain; Sudhir K. Paidesetty; Rabindra N. Padhy; Pawan K. Singh
Introduction: Mycobacterium tuberculosis has been a grievous pathogen causing staggering infections worldwide; especially its recently drug resistant strains are intractable. The MurA ligase of cell-wall peptidoglycan pathway is the suitable target often used for drug development. Methods: A homology model of MurA enzyme of M. tuberculosis was generated and validated by a Ramachandran plot for use in molecular docking studies with 13 cyano-compounds, along with 4 first-line anti-tuberculosis drugs, isoniazid, pyrazinamide, ethambutol and rifampicin. Results: Docking scores of two most effective cyano-compounds, pitipeptolides F and pitipeptolides D are -13.765 and -13.678 kcal/mol, respectively, whereas that of rifampicin is -9.173 kcal/mol. Computed LD50 values of the majority cyano-compounds were 200 mg/kg in mouse models, whereas that of isoniazid is 133 mg/kg. Most cyano-compounds, isoniazid and rifampicin are of the class III toxicity level or slightly toxic. Isoniazid has the highest LC50 value around 0.7 mmol against fathead minnow fish, but it is carcinogenic and mutagenic, as known from the computational prediction. Conclusion: Effective-most cyano-compounds, pitipeptolides F and pitipeptolides D could be used as alterative/complementary agents against recently reported drug-resistant strains of M. tuberculosis. © 2017, Association of Pharmaceutical Teachers of India. All rights reserved.
Cyanobacteria as a "green" option for sustainable agriculture
(Wiley Blackwell, 2013) Radha Prasanna; Anjuli Sood; Sachitra Kumar Ratha; Pawan K. Singh
The use of indigenous native technologies and environment-friendly supplements forms the basis of "green" technologies for environmentally safe and sustainable agriculture. This article discusses different aspects of the use of cyanobacterial inoculants to enhance crop productivity and improve/sustain soil fertility. The sustaining of fertility of rice fields is due to cyanobacteria, as they perform many roles in the soil ecosystem. The beneficial effects of algalization are attributed to the growth-promoting substances produced by cyanobacteria and the temporary immobilization of added nitrogen. There is a need to develop more effective formulations and useful markers for the widespread use of cyanobacterial biofertilizers. Studies undertaken to characterize the abundance, diversity, and metabolic capabilities of cyanobacteria isolated from the rice rhizosphere reveal that the isolates are efficient in enhancing the germination and growth of wheat and rice seeds. © 2014 John Wiley & Sons, Ltd.
Development and characterization of the 4th CSISA-spot blotch nursery of bread wheat
(Kluwer Academic Publishers, 2015) Pawan K. Singh; Yong Zhang; Xinyao He; Ravi P. Singh; Ramesh Chand; Vinod K. Mishra; Paritosh K. Malaker; Mostofa A. Reza; Mokhlesur M. Rahman; Rabiul Islam; Apurba K. Chowdhury; Prateek M. Bhattacharya; Ishwar K. Kalappanavar; José Crossa; Arun K. Joshi
Spot blotch (SB) caused by Cochliobolus sativus is a serious biotic stress to wheat in warm and humid areas, particularly South Asia (SA). In order to support South Asian farmers to combat SB, International Maize and Wheat Improvement Center (CIMMYT) established an efficient SB screening system at Agua Fria, Mexico and developed a nursery under the project - Cereal Systems Initiative for South Asia (CSISA). The materials used to form CSISA-SB nursery were selected from advanced breeding lines from different wheat breeding programs at CIMMYT. Seed of CSISA-SB nursery was produced at disease-free plots at El Batan and Mexicali, and distributed to SA after rigorous seed health checks. The 4th CSISA-SB, made available in 2012, comprised 50 entries including two resistant and two susceptible checks. The nursery was evaluated in seven locations in Mexico, India, and Bangladesh in the 2012–13 cropping season. The results indicated that although few lines exhibited stable resistance across locations due to strong G × E interaction, promising lines with SB resistance and good agronomy can still be identified in each location. The two most promising lines showing consistent spot blotch resistance across the regions were CHUKUI#1 (CIMMYT germplasm bank identification number, GID 6178575) and VAYI#1 (GID 6279248). These lines could be promoted as sources of SB resistance or directly released as cultivars in SA. © 2015, Koninklijke Nederlandse Planteziektenkundige Vereniging.
Dissecting Quantitative Trait Loci for Spot Blotch Resistance in South Asia Using Two Wheat Recombinant Inbred Line Populations
(Frontiers Media S.A., 2021) Chandan Roy; Navin C. Gahtyari; Xinyao He; Vinod K. Mishra; Ramesh Chand; Arun K. Joshi; Pawan K. Singh
Spot blotch (SB) disease causes significant yield loss in wheat production in the warm and humid regions of the eastern Gangetic plains (EGP) of South Asia (SA). Most of the cultivated varieties in the eastern part of SA are affected by SB under favorable climatic conditions. To understand the nature of SB resistance and map the underlying resistant loci effective in SA, two bi-parental mapping populations were evaluated for 3 years, i.e., 2013–2015 for the BARTAI × CIANO T79 population (denoted as BC) and 2014–2016 for the CASCABEL × CIANO T79 population (CC), at Varanasi, Uttar Pradesh, India. DArTSeq genotyping-by-sequencing (GBS) platform was used for genotyping of the populations. Distribution of disease reaction of genotypes in both populations was continuous, revealing the quantitative nature of resistance. Significant “genotype,” “year,” and “genotype × year” interactions for SB were observed. Linkage map with the genome coverage of 8,598.3 and 9,024.7 cM in the BC and CC population, respectively, was observed. Two quantitative trait loci (QTLs) were detected on chromosomes 1A and 4D in the BC population with an average contribution of 4.01 and 12.23% of the total phenotypic variation (PV), respectively. Seven stable QTLs were detected on chromosomes 1B, 5A, 5B, 6A, 7A, and 7B in the CC population explaining 2.89–10.32% of PV and collectively 39.91% of the total PV. The QTL detected at the distal end of 5A chromosome contributed 10.32% of the total PV. The QTLs on 6A and 7B in CC could be new, and the one on 5B may represent the Sb2 gene. These QTLs could be used in SB resistance cultivar development for SA. © Copyright © 2021 Roy, Gahtyari, He, Mishra, Chand, Joshi and Singh.
Establishing an association between molecular markers and sheath blight (Rhizoctonia solani Kuhn) resistance in rice
(Southern Cross Publishing, 2016) Megha Joshi; Pawan K. Singh; Showkat A. Waza; Vineeta Singh; Sanjay Goswami; Pallavi; Sujit Kumar; Anil K. Singh; Najam W. Zaidi; Uma S. Singh
The use of multiple regression analysis to validate molecular markers associated with sheath blight resistance was carried out in 73 germplasm accessions of rice. Data on disease reaction was recorded as lesion size and used for calculation of AUDPC (Area Under Disease Progress Curve) and Percent Disease Index (PDI). A variation in AUDPC ranging from 217.78 to 793.33 with a mean value of 532.51 was recorded for the genotypes infected with sclerotia. PDI ranged from 28.89 to 84.44 with the mean values of 55.40 for infected lines. The AUDPC and PDI values for resistant check Tetep were found to be 432.70 and 45.22, respectively. Higher AUDPC and PDI values serve as an indication for susceptibility towards the disease reaction. The PIC value for the SSR loci varied from 0.225 to 0.743 with an average value of 0.47. Markers RM336, RM209, RM251 and RM224 were most informative on the basis of their high PIC values. UPGMA clustering based on molecular data and AUDPC were found to be in good agreement with each other. Twenty five germplasm accessions were grouped as common in cluster I of dendrogram generated by all alleles, cluster I of dendrogram constructed by Tetep specific alleles, and clusters I and II of the AUDPC dendrogram. Multiple regression analysis revealed that the two markers RM251175 and RM257150 may be considered as markers for association with low disease index (resistance to sheath blight) in rice. Amongst the germplasm accessions, IC383396 and IC426017 behaved as potentially resistant to sheath blight.
Evaluation of Antibacterial and Antioxidant Efficacy of the Fern Azolla caroliniana Symbiotic with the Cyanobacterium Anabaena azollae
(Springer India, 2015) Nabakishore Nayak; Rabindra N. Padhy; Pawan K. Singh
Antibacterial efficacy of the water-fern, Azolla caroliniana Willd., symbiotic with the nitrogen fixing cyanobacterium, Anabaena azollae against seven multidrug resistant pathogenic bacteria were evaluated. Antioxidant and organoleptic properties of the fern were also assessed. Most Gram-negative and Gram-positive bacteria used in this study were highly resistant to 17 antibiotics of aminoglycoside, beta-lactam, cephalosporin and fluoroquinolone groups, as recorded from Kirby-Bauer method. The methanolic extract of A. caroliniana generated 20 mm as the maximum size of zone of inhibition against Staphylococcus aureus, as recorded from the agar-well diffusion method. The minimum inhibitory concentration value, 1.89 mg/ml was due to the methanolic extract against S. aureus and Proteus mirabilis, while the value, 4.27 mg/ml was against Enterococcus sp., Enterobacter aerogenes, Escherichia coli and Pseudomonas aeruginosa. The minimum bactericidal concentration value, 4.27 mg/ml was of the methanolic extract against S. aureus and P. mirabilis, while the value, 21.67 mg/ml was recorded against Citrobacter sp., E. aerogenes, E. coli and P. aeruginosa. Fifty percent inhibition concentration values of free radical scavenging activities of the fern with free radical generating chemicals, 1,1-diphenyl-2-picryl hydrazyl, as well as, 2, 2-azino-bis (ethylbenzthiazoline-6-sulfonic acid), hydrogen peroxide and nitric oxide of the methanolic extract were 8, 10, 10, and 78.8 µg/ml, respectively. In four solvent-extracts with methanol, ethanol, chloroform and n-hexane, several common phytochemicals and phenols were present, while alkaloids and saponins were absent. Processed Azolla was tasteless but not unpalatable. Azollacaroliniana could be used as an antibacterial as well as an antioxidant agent in complementary and alternate medicine. © 2014, The National Academy of Sciences, India.
Genomic selection for spot blotch in bread wheat breeding panels, full-sibs and half-sibs and index-based selection for spot blotch, heading and plant height
(Springer Science and Business Media Deutschland GmbH, 2022) Philomin Juliana; Xinyao He; Jesse Poland; Krishna K. Roy; Paritosh K. Malaker; Vinod K. Mishra; Ramesh Chand; Sandesh Shrestha; Uttam Kumar; Chandan Roy; Navin C. Gahtyari; Arun K. Joshi; Ravi P. Singh; Pawan K. Singh
Key message: Genomic selection is a promising tool to select for spot blotch resistance and index-based selection can simultaneously select for spot blotch resistance, heading and plant height. Abstract: A major biotic stress challenging bread wheat production in regions characterized by humid and warm weather is spot blotch caused by the fungus Bipolaris sorokiniana. Since genomic selection (GS) is a promising selection tool, we evaluated its potential for spot blotch in seven breeding panels comprising 6736 advanced lines from the International Maize and Wheat Improvement Center. Our results indicated moderately high mean genomic prediction accuracies of 0.53 and 0.40 within and across breeding panels, respectively which were on average 177.6% and 60.4% higher than the mean accuracies from fixed effects models using selected spot blotch loci. Genomic prediction was also evaluated in full-sibs and half-sibs panels and sibs were predicted with the highest mean accuracy (0.63) from a composite training population with random full-sibs and half-sibs. The mean accuracies when full-sibs were predicted from other full-sibs within families and when full-sibs panels were predicted from other half-sibs panels were 0.47 and 0.44, respectively. Comparison of GS with phenotypic selection (PS) of the top 10% of resistant lines suggested that GS could be an ideal tool to discard susceptible lines, as greater than 90% of the susceptible lines discarded by PS were also discarded by GS. We have also reported the evaluation of selection indices to simultaneously select non-late and non-tall genotypes with low spot blotch phenotypic values and genomic-estimated breeding values. Overall, this study demonstrates the potential of integrating GS and index-based selection for improving spot blotch resistance in bread wheat. © 2022, The Author(s).
Growth and biochemical characterization of associations between cyanobionts and wheat seedlings in co-culturing experiments
(2011) Anjuli Sood; Pawan K. Singh; Arun Kumar; Rajendra Singh; Radha Prasanna
N2-fixing cyanobacteria are unique in their capacity to form symbiotic associations with a wide range of eukaryotic hosts belonging to different plant groups. The present study was undertaken to analyze the interactions of the cyanobiont PI 01 (from Azolla pinnata) and Nostoc PCC 9229 (from Gunnera monoika) with wheat seedlings, in co-culturing experiments. Each of the cyanobionts enhanced significantly the volume of root and shoot biomass in the experimental cultures. The transverse sections of roots in the co-cultured seedlings revealed the presence of aseriate packets of cyanobionts below the root epidermis. The investigated cyanobionts excreted amino acids (His, Met, Val) and sugars into the medium, while indoleacetic acid was detected when the cyanobionts were grown in a tryptophan containing medium. During the co-culturing, sugars and proline were detected in the extracellular filtrates. It can be hypothesized that these sugars and amino acids may serve as signal substances in the development of functional associations between the relevant cyanobionts and the wheat seedlings. © 2011 Versita Warsaw and Springer-Verlag Wien.
Hydrogen peroxide prompted lignification affects pathogenicity of hemi-bio-trophic pathogen bipolaris sorokiniana to wheat
(Korean Society of Plant Pathology, 2019) Ajit Poudel; Sudhir Navathe; Ramesh Chand; Vinod K. Mishra; Pawan K. Singh; Arun K. Joshi
Spot blotch caused by Bipolaris sorokiniana has spread to more than 9 million ha of wheat in the warm, humid areas of the Eastern Gangetic Plains (EGP) of South Asia and is a disease of major concern in other similar wheat growing regions worldwide. Differential lignin content in resistant and susceptible genotypes and its association with free radicals such as hydrogen peroxide (H2O2), superoxide (O2 -) and hydroxyl radical (OH-) were studied after inoculation under field conditions for two consecutive years. H2O2 significantly influenced lignin content in flag leaves, whereas there was a negative correlation among lignin and H2O2 to the Area Under Disease Progress Curve (AUDPC). The production of H2O2 was higher in the resistant genotypes than susceptible ones. The O2 - and OH- positively correlated with AUDPC but negatively with lignin content. This study illustrates that H2O2 has a vital role in prompting lignification and thereby resistance to spot blotch in wheat. We used cluster analysis to separate the resistant and susceptible genotypes by phenotypic and biochemical traits. H2O2 associated lignin production significantly reduced the number of appressoria and penetration pegs. We visualized the effect of lignin in disease resistance using differential histochemical staining of tissue from resistant and susceptible genotypes, which shows the variable accumulation of hydrogen peroxide and lignin around penetration sites. © The Korean Society of Plant Pathology.
Isolation and characterization of high protein and phycocyanin producing mutants of Arthrospira platensis
(Wiley-VCH Verlag, 2018) Geeta G. Shirnalli; Manish S. Kaushik; Ajay Kumar; Gerard Abraham; Pawan K. Singh
Cyanobacteria are known to exhibit their efficiency in producing high concentrations of compounds of commercial value. Arthrospira is one such cyanobacterium which is considered as important source of protein (65%) and other nutrients. In present study, chemical mutagenesis using N-methyl-Ń-Nitro-nitrosoguanidine (NTG), a proven potent mutagen for cyanobacteria was used to bring stable and desirable alteration in Arthrospira platensis ARM 730. Three morphological mutants (G-1, G-2, and SF) were selected and characterized. The G-1 and G-2 were helical, more bluish in pigmentation than the wild type strain where G-1 also showed enlarged cell size. The SF mutant was an altered straight-filament having maximum biomass. Among three mutants, higher protein and phycocyanin contents were observed in G-1 and G-2 mutants whereas chlorophyll was less in these mutants as compared to wild type strain indicating change in the pigment ratio. Carotenoid content was higher in SF mutant as compared to wild type and other mutants. Variation in total sugar content was not observed in comparison to wild type strain. The analysis of amino acid spectrum of all the mutants and wild type showed significant increase in proline content. Overall, it is revealed from the results that G-1 and G-2 mutants showed higher biomass, phycocyanin, and protein contents in comparison to wild type which indicated their great potential to be used in food and pharmaceutical industries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Natural variation in elicitation of defense-signaling associates to field resistance against the spot blotch disease in bread wheat (Triticum aestivum L.)
(Frontiers Media S.A., 2018) Sandeep Sharma; Ranabir Sahu; Sudhir Navathe; Vinod K. Mishra; Ramesh Chand; Pawan K. Singh; Arun K. Joshi; Shree P. Pandey
Spot blotch, caused by the hemibiotropic fungus Bipolaris sorokiniana, is amongst the most damaging diseases of wheat. Still, natural variation in expression of biochemical traits that determine field resistance to spot blotch in wheat remain unaddressed. To understand how genotypic variations relate to metabolite profiles of the components of defense-signaling and the plant performance, as well as to discover novel sources of resistance against spot blotch, we have conducted field studies using 968 wheat genotypes at 5 geographical locations in South-Asia in 2 years. 46 genotypes were identified as resistant. Further, in independent confirmatory trials in subsequent 3 years, over 5 geographical locations, we re-characterized 55 genotypes for their resistance (above 46 along with Yangmai#6, a well characterized resistant genotype, and eight susceptible genotypes). We next determined time-dependent spot blotch-induced metabolite profiles of components of defense-signaling as well as levels of enzymatic components of defense pathway (such as salicylic acid (SA), phenolic acids, and redox components), and derived co-variation patterns with respect to resistance in these 55 genotypes. Spot blotch-induced SA accumulation was negatively correlated to disease progression. Amongst phenolic acids, syringic acid was most strongly inversely correlated to disease progression, indicating a defensive function, which was independently confirmed. Thus, exploring natural variation proved extremely useful in determining traits influencing phenotypic plasticity and adaptation to complex environments. Further, by overcoming environmental heterogeneity, our study identifies germplasmand biochemical traits that are deployable for spot blotch resistance in wheat along South-Asia. © 2018 Sharma, Sahu, Navathe, Mishra, Chand, Singh, Joshi and Pandey.
Physico-chemical factors influencing spore germination in cyanobacterium Fischerella muscicola
(Wiley-VCH Verlag, 2018) Biranchi N. Mishra; Manish S. Kaushik; Gerard Abraham; Pawan K. Singh
Spore (akinete) formation in the heterocystous and branched filamentous cyanobacterium Fischerella muscicola involves a significant increase in cell size and formation of several endospores in each of the cells. In present study, the physicochemical factors (pH, light sources, nutrient deficiency, nitrogen sources, carbon sources, and growth hormones) affecting the germination of spores of F. muscicola were examined. Increase in spore germination frequency was detected above pH 8 with maximum germination (46.04%) recorded at pH 9, whereas a significant decrease in germination was observed at pH 6 when compared to control (pH 7.6). Spore germination was not observed at pH 5. Among light sources germination frequency followed the following order, that is, red light (39.9%) > white light (33.8%) > yellow light (3.4%) > green light (1.3%) whereas germination did not take place in dark and blue light. Ammonium chloride (NH4Cl) supported maximum (99.5%) germination frequency followed by calcium nitrate (Ca(NO3)2), potassium nitrate (KNO3), and minimum germination was observed in urea. Nutrient (phosphorus, calcium, and magnesium) deficiency significantly enhanced the germination frequency with maximum increase in magnesium (Mg) deficient condition. Further, supplementation of carbon sources (glucose, fructose, and sodium acetate) and growth hormones (IAA and GA) also enhanced the germination frequency in this cyanobacterium. Therefore, it may be concluded that, those factors supporting higher germination frequency could be considered for successful production and use of this cyanobacterium in biofertilizer and other algal production technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Physiological characterization and molecular profiling of toxic and non-toxic isolates of cyanobacterium microcystis
(Triveni Enterprises, 2013) Pranita Jaiswal; Radha Prasanna; Pawan K. Singh
Our investigation aimed to utilize physiological attributes and molecular tools for distinguishing the toxic strain of Microcystis from other non toxic strains, belonging to the same genus. Physiological characterization of five Microcystis isolates indicated that the toxic strain (Ml) exhibited significantly higher pigment accumulation (phycocyanin: 54.20 ng ml -1; allophycocyanin: 18.2 |ig ml-1 ) and sugar content (74.25 ng ml-1 ), which may be providing a competitive advantage for successful colonization and proliferation. Profiling using repeat sequence primers (STRR, Hip) was helpful in distinguishing different strains (M1-M5) and HIP TG profile was unique to Ml. SDS-PAGE profile of the five strains indicated the presence of a unique band (25kDa) in Ml. The combined use of SDS-PAGE and HipTG profiles can help in providing distinct fingerprint for the toxic strain, which can be useful in its identification. © Triveni Enterprises, Lucknow (India).