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H S Shetty - One of the best experts on this subject based on the ideXlab platform.
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Bioimaging structural signatures of the oomycete pathogen Sclerospora graminicola in pearl millet using different microscopic techniques
Scientific Reports, 2019Co-Authors: H S Shetty, Sudisha Jogaiah, Sharada Mysore Suryanarayan, Aditya Rao Shimoga Janakirama, Michael Hansen, Hans Jørgen Lyngs Jørgensen, Lam-son Phan TranAbstract:In this case study, the mycelium growth of Sclerospora graminicola in the infected tissues of pearl millet and the process of sporulation and liberation of sporangia and zoospores were observed using four different microscopic techniques. The cotton blue-stained samples observed under light microscope revealed the formation of zoospores with germ tubes, appressoria and initiation of haustorium into the host cells, while the environmental scanning electron microscopy showed the rapid emergence of sporangiophores with dispersed sporangia around the stomata. For fluorescence microscopy, the infected leaf samples were stained with Fluorescent Brightener 28 and Calcofluor White, which react with β-glucans present in the mycelial walls, sporangiophores and sporangia. Calcoflour White was found to be the most suitable for studying the structural morphology of the pathogen. Therefore, samples observed by confocal laser scanning microscopy (CLSM) were pre-treated with Calcofluor White, as well as with Syto-13 that can stain the cell nuclei. Among the four microscopic techniques, CLSM is ideal for observing live host-pathogen interaction and studying the developmental processes of the pathogen in the host tissues. The use of different microscopic bioimaging techniques to study pathogenesis will enhance our understanding of the morphological features and development of the infectious propagules in the host.
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Trichogenic-selenium nanoparticles enhance disease suppressive ability of Trichoderma against downy mildew disease caused by Sclerospora graminicola in pearl millet
Scientific Reports, 2017Co-Authors: Boregowda Nandini, H S Shetty, Harischandra Sripathy Prakash, P. Hariprasad, N. P. GeethaAbstract:Trichoderma spp. are well known biocontrol agents used against phytopathogens. In the present work Trichoderma-mediated Selenium nanoparticles (SeNPs) were synthesized and extent of downy mildew (DM) disease control in pearl millet (PM) was studied. Six species of Trichoderma namely, T. asperellum, T. harzianum, T. atroviride, T. virens, T. longibrachiatum and T. brevicompactum were evaluated in the form of culture filtrate (CF), cell lysate (CL) and crude cell wall (CW) to synthesize SeNPs. All these components produced SeNPs, but CF was significant than CL and CW. The size of SeNPs ranged from 49.5 to 312.5 nm with zeta potential of +3.3 mv to −200 mv. The nanoparticles suppressed the growth, sporulation and zoospore viability of Sclerospora graminicola and these biological activities were inversely proportional to the size of SeNPs. Under greenhouse conditions, application of SeNPs and T. asperellum together enhanced the early plant growth and suppressed DM incidence as compared to their individual application. This study demonstrated the ability of Trichogenic-SeNPs to suppress growth and proliferation of S. graminicola, the incitant of DM of PM and their activity is inversely proportional to size of nanoparticles.
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Lactuca sativa mediated chitinase activity and resistance in pearl millet against Sclerospora graminicola
African Journal of Plant Science, 2013Co-Authors: S. R. Mythrashree, H S Shetty, N. P. Geetha, H. G. Pushpalatha, M. Murali, K. N. AmrutheshAbstract:Pearl millet seeds were treated with latex extracts (L1- 50 µl, L2- 100 µl and L3- 200 µl) ofAsclepias curassavica, Calotropis gigantea, Croton sp., Eucalyptus alba, Morus alba,Nerium odoratum, Lactuca sativa and Tridax procumbens were applied on pearl millet seeds for 3 and 6 h to evaluate their role in growth promotion and downy mildew resistance. Latex extracts of all tested plants improved vegetative parameters when compared with the control. L. sativa (L2) at 3 h showed 38 and 18% increase in seed germination and vigor, respectively, over the control. Plant height, shoot fresh and dry weight, number of tillers and leaf surface area also increased upon latex treatment. Green house studies indicated that L. sativa required four days after challenge inoculation to build up maximum resistance and offered 54% protection against downy mildew. Resistance induction was evident with increased activities of phenylalanine ammonia lyase (PAL) (four fold), peroxidase (POX) (three fold) and chitinase (three fold) in L. sativa(L2) treated seedlings challenged with the pathogen as compared to control seedlings. Key words: Downy mildew, induced resistance, Lactuca sativa, pearl millet, plant extracts, Sclerospora graminicola.
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Induction of systemic resistance in pearl millet (Pennisetum glaucum) against downy mildew (Sclerospora graminicola) by Datura metel extract
Crop Protection, 2009Co-Authors: Shivakumar P. Devaiah, Geetha Heluvarahundi Mahadevappa, H S ShettyAbstract:Abstract A leaf extract of Datura metel protected pearl millet plants against downy mildew disease caused by Sclerospora graminicola . Of the different concentrations tested, the highest seed germination and seedling vigor was recorded when seeds were treated with a 2% extract for 3 h. When tested for induction of resistance against downy mildew disease, seed treatment with D. metel extract resulted in 79 and 67% protection under greenhouse and field conditions respectively. The resistance offered by D. metel extract was demonstrated to be systemic acquired resistance (SAR) and was active at both early and later stages of plant growth. An association between induction of resistance and salicylic acid (SA) content was drawn by quantifying the enhanced level of endogenous salicylic acid in root (4-fold) and shoot (10-fold) portions of induced seedlings. The highest levels of salicylic acid were observed in roots and shoots of highly resistant (HR) and SAR seedlings 3 and 6 h after inoculation respectively. The defense related enzymes, peroxidase, β -1,3-glucanase and chitinase, showed 1.5–2.6-fold increased activity in SAR seedlings. In addition to disease protection, plants with induced resistance showed 1.2–1.3-fold increased growth, in biomass, number of earheads and grain yield. Taken together, our results strongly suggest that seed treatment with D. metel extract provides protection against the downy mildew pathogen.
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Molecular Characterization of Sclerospora graminicola, the Incitant of Pearl Millet Downy Mildew Using ISSR Markers
Journal of Phytopathology, 2009Co-Authors: J. Sudisha, R. P. Thakur, V. P. Rao, Soshee Ananda Kumar, H S ShettyAbstract:The DNA polymorphism among 22 isolates of Sclerospora graminicola, the causal agent of downy mildew disease of pearl millet was assessed using 20 inter simple sequence repeats (ISSR) primers. The objective of the study was to examine the effectiveness of using ISSR markers for unravelling the extent and pattern of genetic diversity in 22 S. graminicola isolates collected from different host cultivars in different states of India. The 19 functional ISSR primers generated 410 polymorphic bands and revealed 89% polymorphism and were able to distinguish all the 22 isolates. Polymorphic bands used to construct an unweighted pair group method of averages (UPGMA) dendrogram based on Jaccard's co-efficient of similarity and principal coordinate analysis resulted in the formation of four major clusters of 22 isolates. The standardized Nei genetic distance among the 22 isolates ranged from 0.0050 to 0.0206. The UPGMA clustering using the standardized genetic distance matrix resulted in the identification of four clusters of the 22 isolates with bootstrap values ranging from 15 to 100. The 3D-scale data supported the UPGMA results, which resulted into four clusters amounting to 70% variation among each other. However, comparing the two methods show that sub clustering by dendrogram and multi dimensional scaling plot is slightly different. All the S. graminicola isolates had distinct ISSR genotypes and cluster analysis origin. The results of ISSR fingerprints revealed significant level of genetic diversity among the isolates and that ISSR markers could be a powerful tool for fingerprinting and diversity analysis in fungal pathogens.
H. Shekar Shetty - One of the best experts on this subject based on the ideXlab platform.
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Draft genome sequence of Sclerospora graminicola, the pearl millet downy mildew pathogen.
Biotechnology Reports, 2017Co-Authors: S. Chandra Nayaka, C.tara Satyavathi, P.b.kavi Kishor, T.a. Anoop, Milner M. Kumar, Boney Kuriakose, H. Shekar Shetty, Rattan Yadav, M.s.s. Nagaraju, Navajeet ChakravarttyAbstract:Sclerospora graminicola pathogen is the most important biotic production constraints of pearl millet in India, Africa and other parts of the world. We report a de novo whole genome assembly and analysis of pathotype 1, one of the most virulent pathotypes of S. graminicola from India. The draft genome assembly contained 299,901,251 bp with 65,404 genes. This study may help understand the evolutionary pattern of pathogen and aid elucidation of effector evolution for devising effective durable resistance breeding strategies in pearl millet.
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Response of pearl millet downy mildew (Sclerospora graminicola) to diverse fungicides
International Journal of Pest Management, 2015Co-Authors: Shantharaj Deepak, H. Shekar Shetty, G Chaluvaraju, P. Basavaraju, Kn Amuthesh, Gyula OrosAbstract:The inhibitory effect of 15 commercial and five experimental fungicides was assessed both in greenhouse and field experiments against Sclerospora graminicola, the causative agent of pearl millet downy mildew disease. Chemicals differed in anti-mildew activity. However, neither the pathogen nor the host plant was completely tolerant to any compounds tested. The plants depressed by fungicides in the germling stage recovered until formation of inflorescence, so this activity did not significantly influence grain yield. There was a significant correlation between antisporulant activity of compounds evaluated on detached leaf segments and their positive effect on yield performance. All compounds increased the grain yield of downy mildewed pearl millet when applied in the maximum doses tolerated by pearl millet. However, analysis of the cost-return budget showed that disease control < 30% is uneconomic. Fungicides of the acylanilide series exhibited the highest protective effect (over 95%) and andoprim, drazoxolon and efosit were also effective.
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Elicitation of Induced Resistance in Pearl Millet a gainst Sclerospora graminicola through Seed Treatment with Medicinal Plant Extracts
2015Co-Authors: P. H. Thejaswini, H. Shekar Shetty, H. B. MaheshaAbstract:Seed treatment is the use of seed as delivery syste m or deployment agent for different materials. Seed treatments offer economical and less polluting delivery system compared to other field application techniques, since only a relatively sma ll amount of material is applied and is in immediate contact with target site. Seed coating w ith antagonistic microorganisms has been abundantly documented and there are several lines oexperimental evidences to show that seed treatment with bacterial and fungal antagonistic are effective in protecting germinating embryos from pathogens. Reports clearly indicate the possib ility of inducing Systemic acquired resistance (SAR) in host plant against pathogens by seed treat ment with SAR inducers. Induction of resistance by seed treatment is of practical way to deliver be nefits of SAR. This artificial manipulation of plants’ defense system provides a biologically, env ironmentally and commercially valuable, alternative to existing plant disease managing prac tices. The paper reports use of seed treatment in effectively inducing SAR in otherwise susceptible p earl millet against Sclerospora graminicola (Sacc.) Schroet. The induced resistance is correlat ed to increase in growth parameters and increase in yield.
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Cloning and development of pathotype-specific SCAR marker associated with Sclerospora graminicola isolates from pearl millet
Australasian Plant Pathology, 2009Co-Authors: J. Sudisha, S. Ananda Kumar, S. R. Niranjana, N. P. Shetty, H. Shekar ShettyAbstract:Downy mildew pathogen of pearl millet in India is associated with the spread of the highly virulent Sclerospora graminicola pathotype-1. Twenty-seven S. graminicola isolates were screened using 20 inter simple sequence repeats (ISSR). Dinucleotide repeat primer [17898A-(CA)_6 AC] amplified a ∼600 bp fragment specific to five isolates of pathotype-1 (Sg 048, Sg 153, Sg 212, DM-11 and DM-90). The ISSR fragment linked with pathotype-1 was cloned successfully and sequenced. To convert ISSR fragments into pathotype-specific sequence characterised amplified region (SCAR) markers, PCR primers were designed using a sequence of the cloned DNA fragment. PCR amplification using SCAR primer pair (UOM3-Sg-Path1-F/R) amplified a single 284 bp band only in isolates of S. graminicola pathotype-1. This SCARprimer pair did not amplify the 284 bp product from the other five S. graminicola pathotypes or a negative control, which demonstrates primer specificity for pathotype-1. The SCAR primer pair (UOM3-Sg-Path1-F/R) obtained in this study will provide a valuable tool for rapid identification and specific detection of S. graminicola pathotype-1.
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Chitosan enhances disease resistance in pearl millet against downy mildew caused by Sclerospora graminicola and defence-related enzyme activation.
Pest Management Science, 2008Co-Authors: G. Manjunatha, K. S. Roopa, Geetha N Prashanth, H. Shekar ShettyAbstract:BACKGROUND: The present study investigated the effect of chitosan seed priming on the induction of disease resistance in pearl millet against downy mildew disease caused by Sclerospora graminicola (Sacc.) Schroet. RESULTS: Pearl millet seeds were primed with chitosan at different concentrations: 0.5, 1.5, 2.5 and 3 g kg−1 seed. Of the different concentrations, 2.5 g kg−1 was found to be optimum, with enhanced seed germination of 99% and seedling vigour of 1782, whereas the untreated control recorded values of 87% and 1465 respectively. At optimum concentration, chitosan did not inhibit sporulation and release of zoospores from sporangia. Furthermore, pearl millet seedlings raised after seed treatment with chitosan showed an increased level of the defence-related enzymes chitosanase and peroxidase as compared with the untreated pearl millet seedlings on downy mildew pathogen inoculation. The effect of chitosan in reducing downy mildew incidence was evaluated in both greenhouse and field conditions, in which respectively 79.08 and 75.8% disease protection was obtained. CONCLUSION: Chitosan was effective in protecting pearl millet plants against downy mildew under both greenhouse and field conditions by inducing resistance against the pathogen. Thus, chitosan formulation can be recommended for seed treatment in the management of downy mildew disease. Copyright © 2008 Society of Chemical Industry
Shantharaj Deepak - One of the best experts on this subject based on the ideXlab platform.
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Response of pearl millet downy mildew (Sclerospora graminicola) to diverse fungicides
International Journal of Pest Management, 2015Co-Authors: Shantharaj Deepak, H. Shekar Shetty, G Chaluvaraju, P. Basavaraju, Kn Amuthesh, Gyula OrosAbstract:The inhibitory effect of 15 commercial and five experimental fungicides was assessed both in greenhouse and field experiments against Sclerospora graminicola, the causative agent of pearl millet downy mildew disease. Chemicals differed in anti-mildew activity. However, neither the pathogen nor the host plant was completely tolerant to any compounds tested. The plants depressed by fungicides in the germling stage recovered until formation of inflorescence, so this activity did not significantly influence grain yield. There was a significant correlation between antisporulant activity of compounds evaluated on detached leaf segments and their positive effect on yield performance. All compounds increased the grain yield of downy mildewed pearl millet when applied in the maximum doses tolerated by pearl millet. However, analysis of the cost-return budget showed that disease control < 30% is uneconomic. Fungicides of the acylanilide series exhibited the highest protective effect (over 95%) and andoprim, drazoxolon and efosit were also effective.
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Hydroxyproline-rich glycoproteins accumulate in pearl millet after seed treatment with elicitors of defense responses against Sclerospora graminicola
Physiological and Molecular Plant Pathology, 2010Co-Authors: Neerakkal Sujeeth, Shekar H. Shetty, Shantharaj Deepak, Ramachandra K. Kini, Sekhar Shailasree, Jacques HilleAbstract:The accumulation of hydroxyproline-rich glycoproteins (HRGPs) was investigated after induction of resistance in pearl millet against downy mildew caused by Sclerospora graminicola. Treatment of susceptible pearl millet seeds with various biotic and abiotic elicitors resulted in increased HRGP content in the cell walls of coleoptiles at 9 h after inoculation. Similar results with increased accumulation at 4-6 h after inoculation were obtained in suspension cells of pearl millet. Maximum HRGP accumulation was observed in seedlings raised from susceptible seeds treated with chitosan and Pseudomonas fluorescens. Western blot analysis with MAC 265 (a rat monoclonal antibody raised against pea HRGP) identified three proteins of 27, 17 and 14 kDa in resistant cultivars. The absence of the 14 kDa HRGP was observed in susceptible cultivars as reported earlier. The induced accumulation of the 14 kDa HRGP upon elicitor treatments was observed in the present study. Peroxidase and hydrogen peroxide, essential components for HRGP cross-linking, were also increased in samples treated with these elicitors. A tissue specific increase in HRGP at the regions around vascular bundles was observed upon chitosan treatment. The results presented will have a presumed importance in identifying the susceptible pearl millet varieties and improving those using elicitors of defense for field applications. (C) 2010 Elsevier Ltd. All rights reserved.
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Hypersensitive reaction and P/HRGP accumulation is modulated by nitric oxide through hydrogen peroxide in pearl millet during Sclerospora graminicola infection.
Physiological and Molecular Plant Pathology, 2009Co-Authors: G. Manjunatha, Shantharaj Deepak, Prashanth N. Geetha, S. Niranjan-raj, Ramachandra K. Kini, H S ShettyAbstract:Abstract Priming of pearl millet seedlings with nitric oxide (NO) donors sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG) induced hypersensitive reactions (HR) and accumulation of Proline/Hydroxyproline-rich glycoprotein (P/HRGP) during infection by downy mildew pathogen Sclerospora graminicola . Such defense responses were specifically altered by concentration of NO donors resulting in the modulation of endogenous NO in seedling tissues. The stoichiometric interactions of NO and hydrogen peroxide (H 2 O 2 ) when followed in relation to HR and P/HRGP accumulation, the degree of defense response varied with H 2 O 2 level, the latter being largely influenced by NO concentration. Therefore, balancing NO and H 2 O 2 is vital for optimum expression of defense responses for imparting disease resistance.
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purification and characterization of proline hydroxyproline rich glycoprotein from pearl millet coleoptiles infected with downy mildew pathogen Sclerospora graminicola
Phytochemistry, 2007Co-Authors: Shantharaj Deepak, Shekar H. Shetty, Ramachandra K. Kini, Sekhar Shailasree, Neerakkal Sujeeth, Axel MithöferAbstract:Abstract Hydroxyproline-rich glycoproteins (HRGPs) are important plant cell wall structural components, which are also involved in response to pathogen attack. In pearl millet, deposition and cross-linking of HRGPs in plant cell walls was shown to contribute to the formation of resistance barriers against the phytopathogenic oomycete Sclerospora graminicola . In the present study, the purification and characterization of HRGPs that accumulated in coleoptiles of pearl millet seedlings in response to S. graminicola inoculation has been carried out. Periodic acid Schiff’s staining revealed that the purified protein was a glycoprotein. The protein to carbohydrate ratio was determined to be 95.5%:4.5% (w/w). Proline amounted for 20 mol% of the total amino acids as indicated by amino acid composition analysis. The isolated protein had a p I of 9.8 and was shown to be composed of subunits of 27, 17, and 14 kDa. Cross reactivity with the monoclonal antibody MAC 265 and the presence of the signature amino acid sequence, PVYK, strongly suggested to classify the purified glycoprotein as a member of the P/HRGPs class. In the presence of horseradish peroxidase and H 2 O 2 the purified glycoprotein served as a substrate for oxidative cross-linking processes.
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Antisporulant Activity of Watery Extracts of Plants against Sclerospora graminicola Causing Downy Mildew Disease of Pearl Millet
American Journal of Agricultural and Biological Sciences, 2007Co-Authors: Shantharaj Deepak, H. Shekar Shetty, Gyula Oros, S. G. Sathyanarayana, S. SashikanthAbstract:Watery extracts of forty plant species commonly growing in across India have been screened for antisporulant activity against Sclerospora graminicola (Sacc.) Schroet., the causative agent of pearl millet downy mildew. The collection represented 38 genera of 30 families. The extracts of thirteen species did not show any effect, whereas the activity of extracts of Allium sativum, Clematis gouriana, Evolvulus alsinoides, Mimusops elengi, Parthenium hysterophorus, Piper nigrum and Tagetes erecta were commensurable to that of marketed botanical fungicides and Mikal 70 wp. The crude extracts of 12 species (Agave americana, Aloe vera, Artemisia parviflora, Citrus limon, Citrus sinensis, Eucalyptus globosus, Euphorbia hirta, Leucas aspera, Murraya koenigi, Ocimum sanctum, Santalum album and Zingiber offinale) completely inhibited the zoosprorangium formation while in the case of remaining 8 plants the crude extracts reduced only partially the sporulation. The antisporulant activity of commercialised Azadirachta preparation (Nutri-Neem) was more pronounced than that of Reynutria based one (Milsana) and Sabadilla (veratrin), however, these botanical preparations held off synthetic fungicides and the most active watery extracts.
Axel Mithöfer - One of the best experts on this subject based on the ideXlab platform.
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purification and characterization of proline hydroxyproline rich glycoprotein from pearl millet coleoptiles infected with downy mildew pathogen Sclerospora graminicola
Phytochemistry, 2007Co-Authors: Shantharaj Deepak, Shekar H. Shetty, Ramachandra K. Kini, Sekhar Shailasree, Neerakkal Sujeeth, Axel MithöferAbstract:Abstract Hydroxyproline-rich glycoproteins (HRGPs) are important plant cell wall structural components, which are also involved in response to pathogen attack. In pearl millet, deposition and cross-linking of HRGPs in plant cell walls was shown to contribute to the formation of resistance barriers against the phytopathogenic oomycete Sclerospora graminicola . In the present study, the purification and characterization of HRGPs that accumulated in coleoptiles of pearl millet seedlings in response to S. graminicola inoculation has been carried out. Periodic acid Schiff’s staining revealed that the purified protein was a glycoprotein. The protein to carbohydrate ratio was determined to be 95.5%:4.5% (w/w). Proline amounted for 20 mol% of the total amino acids as indicated by amino acid composition analysis. The isolated protein had a p I of 9.8 and was shown to be composed of subunits of 27, 17, and 14 kDa. Cross reactivity with the monoclonal antibody MAC 265 and the presence of the signature amino acid sequence, PVYK, strongly suggested to classify the purified glycoprotein as a member of the P/HRGPs class. In the presence of horseradish peroxidase and H 2 O 2 the purified glycoprotein served as a substrate for oxidative cross-linking processes.
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Purification and characterization of proline/hydroxyproline-rich glycoprotein from pearl millet coleoptiles infected with downy mildew pathogen Sclerospora graminicola.
Phytochemistry, 2006Co-Authors: Shantharaj Deepak, Shekar H. Shetty, Ramachandra K. Kini, Sekhar Shailasree, Neerakkal Sujeeth, Axel MithöferAbstract:Abstract Hydroxyproline-rich glycoproteins (HRGPs) are important plant cell wall structural components, which are also involved in response to pathogen attack. In pearl millet, deposition and cross-linking of HRGPs in plant cell walls was shown to contribute to the formation of resistance barriers against the phytopathogenic oomycete Sclerospora graminicola . In the present study, the purification and characterization of HRGPs that accumulated in coleoptiles of pearl millet seedlings in response to S. graminicola inoculation has been carried out. Periodic acid Schiff’s staining revealed that the purified protein was a glycoprotein. The protein to carbohydrate ratio was determined to be 95.5%:4.5% (w/w). Proline amounted for 20 mol% of the total amino acids as indicated by amino acid composition analysis. The isolated protein had a p I of 9.8 and was shown to be composed of subunits of 27, 17, and 14 kDa. Cross reactivity with the monoclonal antibody MAC 265 and the presence of the signature amino acid sequence, PVYK, strongly suggested to classify the purified glycoprotein as a member of the P/HRGPs class. In the presence of horseradish peroxidase and H 2 O 2 the purified glycoprotein served as a substrate for oxidative cross-linking processes.
Ramachandra K. Kini - One of the best experts on this subject based on the ideXlab platform.
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Hydroxyproline-rich glycoproteins accumulate in pearl millet after seed treatment with elicitors of defense responses against Sclerospora graminicola
Physiological and Molecular Plant Pathology, 2010Co-Authors: Neerakkal Sujeeth, Shekar H. Shetty, Shantharaj Deepak, Ramachandra K. Kini, Sekhar Shailasree, Jacques HilleAbstract:The accumulation of hydroxyproline-rich glycoproteins (HRGPs) was investigated after induction of resistance in pearl millet against downy mildew caused by Sclerospora graminicola. Treatment of susceptible pearl millet seeds with various biotic and abiotic elicitors resulted in increased HRGP content in the cell walls of coleoptiles at 9 h after inoculation. Similar results with increased accumulation at 4-6 h after inoculation were obtained in suspension cells of pearl millet. Maximum HRGP accumulation was observed in seedlings raised from susceptible seeds treated with chitosan and Pseudomonas fluorescens. Western blot analysis with MAC 265 (a rat monoclonal antibody raised against pea HRGP) identified three proteins of 27, 17 and 14 kDa in resistant cultivars. The absence of the 14 kDa HRGP was observed in susceptible cultivars as reported earlier. The induced accumulation of the 14 kDa HRGP upon elicitor treatments was observed in the present study. Peroxidase and hydrogen peroxide, essential components for HRGP cross-linking, were also increased in samples treated with these elicitors. A tissue specific increase in HRGP at the regions around vascular bundles was observed upon chitosan treatment. The results presented will have a presumed importance in identifying the susceptible pearl millet varieties and improving those using elicitors of defense for field applications. (C) 2010 Elsevier Ltd. All rights reserved.
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Hypersensitive reaction and P/HRGP accumulation is modulated by nitric oxide through hydrogen peroxide in pearl millet during Sclerospora graminicola infection.
Physiological and Molecular Plant Pathology, 2009Co-Authors: G. Manjunatha, Shantharaj Deepak, Prashanth N. Geetha, S. Niranjan-raj, Ramachandra K. Kini, H S ShettyAbstract:Abstract Priming of pearl millet seedlings with nitric oxide (NO) donors sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG) induced hypersensitive reactions (HR) and accumulation of Proline/Hydroxyproline-rich glycoprotein (P/HRGP) during infection by downy mildew pathogen Sclerospora graminicola . Such defense responses were specifically altered by concentration of NO donors resulting in the modulation of endogenous NO in seedling tissues. The stoichiometric interactions of NO and hydrogen peroxide (H 2 O 2 ) when followed in relation to HR and P/HRGP accumulation, the degree of defense response varied with H 2 O 2 level, the latter being largely influenced by NO concentration. Therefore, balancing NO and H 2 O 2 is vital for optimum expression of defense responses for imparting disease resistance.
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purification and characterization of proline hydroxyproline rich glycoprotein from pearl millet coleoptiles infected with downy mildew pathogen Sclerospora graminicola
Phytochemistry, 2007Co-Authors: Shantharaj Deepak, Shekar H. Shetty, Ramachandra K. Kini, Sekhar Shailasree, Neerakkal Sujeeth, Axel MithöferAbstract:Abstract Hydroxyproline-rich glycoproteins (HRGPs) are important plant cell wall structural components, which are also involved in response to pathogen attack. In pearl millet, deposition and cross-linking of HRGPs in plant cell walls was shown to contribute to the formation of resistance barriers against the phytopathogenic oomycete Sclerospora graminicola . In the present study, the purification and characterization of HRGPs that accumulated in coleoptiles of pearl millet seedlings in response to S. graminicola inoculation has been carried out. Periodic acid Schiff’s staining revealed that the purified protein was a glycoprotein. The protein to carbohydrate ratio was determined to be 95.5%:4.5% (w/w). Proline amounted for 20 mol% of the total amino acids as indicated by amino acid composition analysis. The isolated protein had a p I of 9.8 and was shown to be composed of subunits of 27, 17, and 14 kDa. Cross reactivity with the monoclonal antibody MAC 265 and the presence of the signature amino acid sequence, PVYK, strongly suggested to classify the purified glycoprotein as a member of the P/HRGPs class. In the presence of horseradish peroxidase and H 2 O 2 the purified glycoprotein served as a substrate for oxidative cross-linking processes.
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Purification and characterization of proline/hydroxyproline-rich glycoprotein from pearl millet coleoptiles infected with downy mildew pathogen Sclerospora graminicola.
Phytochemistry, 2006Co-Authors: Shantharaj Deepak, Shekar H. Shetty, Ramachandra K. Kini, Sekhar Shailasree, Neerakkal Sujeeth, Axel MithöferAbstract:Abstract Hydroxyproline-rich glycoproteins (HRGPs) are important plant cell wall structural components, which are also involved in response to pathogen attack. In pearl millet, deposition and cross-linking of HRGPs in plant cell walls was shown to contribute to the formation of resistance barriers against the phytopathogenic oomycete Sclerospora graminicola . In the present study, the purification and characterization of HRGPs that accumulated in coleoptiles of pearl millet seedlings in response to S. graminicola inoculation has been carried out. Periodic acid Schiff’s staining revealed that the purified protein was a glycoprotein. The protein to carbohydrate ratio was determined to be 95.5%:4.5% (w/w). Proline amounted for 20 mol% of the total amino acids as indicated by amino acid composition analysis. The isolated protein had a p I of 9.8 and was shown to be composed of subunits of 27, 17, and 14 kDa. Cross reactivity with the monoclonal antibody MAC 265 and the presence of the signature amino acid sequence, PVYK, strongly suggested to classify the purified glycoprotein as a member of the P/HRGPs class. In the presence of horseradish peroxidase and H 2 O 2 the purified glycoprotein served as a substrate for oxidative cross-linking processes.