Letteratura scientifica selezionata sul tema "Pathogen attack"
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Articoli di riviste sul tema "Pathogen attack"
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MARQUIS, ROBERT J., IVONE R. DINIZ e HELENA C. MORAIS. "Patterns and correlates of interspecific variation in foliar insect herbivory and pathogen attack in Brazilian cerrado". Journal of Tropical Ecology 17, n. 1 (gennaio 2001): 127–48. http://dx.doi.org/10.1017/s0266467401001080.
Testo completoAbstract (sommario):
Patterns of insect herbivore and leaf pathogen attack are described for 25 plant species (10 trees, 10 shrubs and five herbs) at a Brazilian savanna (cerrado) site. Plant and leaf traits were correlated with interspecific variation in attack by herbivores and pathogens in order to account for differences among plant species. Across all species, pathogen damage was 1.5 times higher than insect damage (17.3% vs. 6.8%, respectively). Most insect damage occurred to young leaves while they were expanding (end of the dry season). In contrast, pathogen attack was low on young expanding leaves at the end of the dry season, increased as those leaves matured in the wet season, but continued to increase through the next dry season. Protein-binding capacity was negatively associated with interspecific differences in insect damage to mature leaves. Protein availability and plant height were positive predictors of pathogen attack among plant species, while leaf expansion rate was a significant negative predictor. Interspecific differences in leaf phenology had little effect on the amount of damage caused by either insects or pathogens. However, new leaves produced during the wet season suffered less insect damage than leaves produced during the dry season, the time of greatest leaf production. Timing of young leaf production affected pathogen attack but the season of escape depended on plant species. In contrast, there was no evidence for escape in space as common species were less likely to suffer high pathogen attack than rare species. New and mature leaf toughness, and time for a leaf to reach full expansion all increased from herbs to shrub to trees, while mature leaf nitrogen decreased in that order.
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OPREA, Daniela, Maria JOITA-PACUREANU, Florin Gabriel ANTON e Luxita RISNOVEANU. "The Resistance of Sunflower to the Attack of Some Pathogenic Agents in the Climate Conditions of the Northeast Baragan". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 79, n. 2 (20 novembre 2022): 54–58. http://dx.doi.org/10.15835/buasvmcn-agr:2022.0034.
Testo completoAbstract (sommario):
Due to its national economic importance, the sunflower crop has established itself as the main oleaginous crop cultivated in Romania. It faces several diseases that are difficult to fight chemically. The creation of hybrids resistant to the attack of pathogens has proven to be an effective, safe, and environmentally friendly solution. This paper aims to examine the resistance of some biological sunflower creations created in Romania, to the attack of Phomopsis helianthi and Phoma macdonaldi fungi, in 2021. The experiment was placed in field conditions with a natural infestation, at A.R.D.S. Braila. The used biological material was represented by nine new sunflower hybrids. Two problem pathogens were studied: Phomopsis helianthi (perfect stage Diaporthe helianthi) and Phoma macdonaldi (perfect stage Leptosphaeria lindquistii). The climatic conditions of 2021 were favorable for the growth of the pathogens. Phoma macdonaldi had an average attack frequency of 38.8% and an average attack intensity of 1.71%, while Phomopsis helianthi recorded average values of 67.8% and 3.08%, respectively. The lowest attack degree of the Phoma macdonaldi pathogen was found in H3 (0.35%). Regarding the pathogen Phomopsis helianthi, the hybrid H3 showed good resistance, with an attack degree of 1.64%.
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Inal, Jameel M., Ephraim A. Ansa-Addo e Sigrun Lange. "Interplay of host–pathogen microvesicles and their role in infectious disease". Biochemical Society Transactions 41, n. 1 (29 gennaio 2013): 258–62. http://dx.doi.org/10.1042/bst20120257.
Testo completoAbstract (sommario):
The release of extracellular vesicles, whether MVs (microvesicles) or exosomes, from host cells or intracellular pathogens is likely to play a significant role in the infection process. Host MVs may fuse with pathogen surfaces to deliver host complement regulatory proteins. They may also deliver cytokines that enhance invasion. Decoy functions are also possible. Whereas host MVs may direct pathogens away from their target cells, pathogen MVs may in turn redirect complement membrane-attack complexes away from their target pathogen. An understanding of the mechanisms of this interplay, bringing about both immune evasion and enhanced invasion, will help to direct future research with a view to rendering pathogens more susceptible to immune attack or in improving drug efficacy. It should also be possible to use MVs or exosomes isolated directly from the pathogens, or from the cells infected with pathogens, to provide alternative vaccination strategies.
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Ruano, Guillermo, e David Scheuring. "Plant Cells under Attack: Unconventional Endomembrane Trafficking during Plant Defense". Plants 9, n. 3 (21 marzo 2020): 389. http://dx.doi.org/10.3390/plants9030389.
Testo completoAbstract (sommario):
Since plants lack specialized immune cells, each cell has to defend itself independently against a plethora of different pathogens. Therefore, successful plant defense strongly relies on precise and efficient regulation of intracellular processes in every single cell. Smooth trafficking within the plant endomembrane is a prerequisite for a diverse set of immune responses. Pathogen recognition, signaling into the nucleus, cell wall enforcement, secretion of antimicrobial proteins and compounds, as well as generation of reactive oxygen species, all heavily depend on vesicle transport. In contrast, pathogens have developed a variety of different means to manipulate vesicle trafficking to prevent detection or to inhibit specific plant responses. Intriguingly, the plant endomembrane system exhibits remarkable plasticity upon pathogen attack. Unconventional trafficking pathways such as the formation of endoplasmic reticulum (ER) bodies or fusion of the vacuole with the plasma membrane are initiated and enforced as the counteraction. Here, we review the recent findings on unconventional and defense-induced trafficking pathways as the plant´s measures in response to pathogen attack. In addition, we describe the endomembrane system manipulations by different pathogens, with a focus on tethering and fusion events during vesicle trafficking.
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Ávila Méndez, Kelly, e Hernán Mauricio Romero. "Plant responses to pathogen attack: molecular basis of qualitative resistance". Revista Facultad Nacional de Agronomía 70, n. 2 (1 maggio 2017): 8225–35. http://dx.doi.org/10.15446/rfna.v70n2.64526.
Testo completoAbstract (sommario):
Pathogens attack plants to assimilate nutrients from them. All plant species have succeeded in overcoming pathogenic attack; therefore disease condition is not the rule but the exception. A co-evolutionary battle has equipped plants with sophisticated defense mechanisms and cognate pathogens with a corresponding arsenal of counter strategies to overcome them. Traditionally, plant-pathogen interaction has been associated with molecules involved in recognition processes giving rise to models such as the "Zig-zag Model". However, this model is being re-evaluated because it is not consistent with the complexity of the interaction. Current models propose a holistic view of a process where the response is not always determined by the interaction of two molecules. This review discusses the main aspects related to qualitative responses in the plant-pathogen interaction and the new proposed models.
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Zhang, Xue, Yang-Shuo Dai, Yu-Xin Wang, Ze-Zhuo Su, Lu-Jun Yu, Zhen-Fei Zhang, Shi Xiao e Qin-Fang Chen. "Overexpression of the Arabidopsis MACPF Protein AtMACP2 Promotes Pathogen Resistance by Activating SA Signaling". International Journal of Molecular Sciences 23, n. 15 (7 agosto 2022): 8784. http://dx.doi.org/10.3390/ijms23158784.
Testo completoAbstract (sommario):
Immune response in plants is tightly regulated by the coordination of the cell surface and intracellular receptors. In animals, the membrane attack complex/perforin-like (MACPF) protein superfamily creates oligomeric pore structures on the cell surface during pathogen infection. However, the function and molecular mechanism of MACPF proteins in plant pathogen responses remain largely unclear. In this study, we identified an Arabidopsis MACP2 and investigated the responsiveness of this protein during both bacterial and fungal pathogens. We suggest that MACP2 induces programmed cell death, bacterial pathogen resistance, and necrotrophic fungal pathogen sensitivity by activating the biosynthesis of tryptophan-derived indole glucosinolates and the salicylic acid signaling pathway dependent on the activity of enhanced disease susceptibility 1 (EDS1). Moreover, the response of MACP2 mRNA isoforms upon pathogen attack is differentially regulated by a posttranscriptional mechanism: alternative splicing. In comparison to previously reported MACPFs in Arabidopsis, MACP2 shares a redundant but nonoverlapping role in plant immunity. Thus, our findings provide novel insights and genetic tools for the MACPF family in maintaining SA accumulation in response to pathogens in Arabidopsis.
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Paphitis, Katherine, Camille Achonu, Sandra Callery, Jonathan Gubbay, Kevin Katz, Matthew Muller, Herveen Sachdeva et al. "Beyond flu: Trends in respiratory infection outbreaks in Ontario healthcare settings from 2007 to 2017, and implications for non-influenza outbreak management". Canada Communicable Disease Report 47, n. 56 (9 giugno 2021): 269–75. http://dx.doi.org/10.14745/ccdr.v47i56a04.
Testo completoAbstract (sommario):
Background: Outbreaks cause significant morbidity and mortality in healthcare settings. Current testing methods can identify specific viral respiratory pathogens, yet the approach to outbreak management remains general. Objectives: Our aim was to examine pathogen-specific trends in respiratory outbreaks, including how attack rates, case fatality rates and outbreak duration differ by pathogen between hospitals and long-term care (LTC) and retirement homes (RH) in Ontario. Methods: Confirmed respiratory outbreaks in Ontario hospitals and LTC/RH reported between September 1, 2007, and August 31, 2017, were extracted from the integrated Public Health Information System (iPHIS). Median attack rates and outbreak duration and overall case fatality rates of pathogen-specific outbreaks were compared in both settings. Results: Over the 10-year surveillance period, 9,870 confirmed respiratory outbreaks were reported in Ontario hospitals and LTC/RH. Influenza was responsible for most outbreaks (32% in LTC/RH, 51% in hospitals), but these outbreaks were shorter and had lower attack rates than most non-influenza outbreaks in either setting. Human metapneumovirus, while uncommon (<4% of outbreaks) had high case fatality rates in both settings. Conclusion: Attack rates and case fatality rates varied by pathogen, as did outbreak duration. Development of specific outbreak management guidance that takes into account pathogen and healthcare setting may be useful to limit the burden of respiratory outbreaks.
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Leary, Alexandre Y., Nattapong Sanguankiattichai, Cian Duggan, Yasin Tumtas, Pooja Pandey, Maria E. Segretin, Jose Salguero Linares, Zachary D. Savage, Rui Jin Yow e Tolga O. Bozkurt. "Modulation of plant autophagy during pathogen attack". Journal of Experimental Botany 69, n. 6 (23 dicembre 2017): 1325–33. http://dx.doi.org/10.1093/jxb/erx425.
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HUGHES, G. "Characterizing crop responses to patchy pathogen attack". Plant Pathology 39, n. 1 (marzo 1990): 2–4. http://dx.doi.org/10.1111/j.1365-3059.1990.tb02469.x.
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Lin, Borong, Xue Qing, Jinling Liao e Kan Zhuo. "Role of Protein Glycosylation in Host-Pathogen Interaction". Cells 9, n. 4 (20 aprile 2020): 1022. http://dx.doi.org/10.3390/cells9041022.
Testo completoAbstract (sommario):
Host-pathogen interactions are fundamental to our understanding of infectious diseases. Protein glycosylation is one kind of common post-translational modification, forming glycoproteins and modulating numerous important biological processes. It also occurs in host-pathogen interaction, affecting host resistance or pathogen virulence often because glycans regulate protein conformation, activity, and stability, etc. This review summarizes various roles of different glycoproteins during the interaction, which include: host glycoproteins prevent pathogens as barriers; pathogen glycoproteins promote pathogens to attack host proteins as weapons; pathogens glycosylate proteins of the host to enhance virulence; and hosts sense pathogen glycoproteins to induce resistance. In addition, this review also intends to summarize the roles of lectin (a class of protein entangled with glycoprotein) in host-pathogen interactions, including bacterial adhesins, viral lectins or host lectins. Although these studies show the importance of protein glycosylation in host-pathogen interaction, much remains to be discovered about the interaction mechanism.
Tesi sul tema "Pathogen attack"
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Mohr, Peter G., e lswan@deakin edu au. "Abscisic acid regulation of plant defence responses during pathogen attack". Deakin University. School of Biological and Chemical Sciences, 2004. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20060927.120049.
Testo completoAbstract (sommario):
The plant hormone, abscisic acid (ABA), has previously been shown to have an impact on the resistance or susceptibility of plants to pathogens. In this thesis, it was shown that ABA had a regulatory effect on an extensive array of plant defence responses in three different plant and pathogen interaction combinations as well as following the application of an abiotic elicitor. In unique studies using ABA deficient mutants of Arabidopsis, exogenous ABA addition or ABA biosynthesis inhibitor application and simulated drought stress, ABA was shown to have a profound effect on the outcome of interactions between plants and pathogens of differing lifestyles and from different kingdoms. The systems used included a model plant and an important agricultural species: Arabidopsis thaliana (Arabidopsis) and Peronospora parasitica (a biotrophic Oomycete pathogen), Arabidopsis and Pseudomonas syringae pathovar tomato (a biotrophic bacterial pathogen) and an unrelated plant species, soybean (Glycine max) and Phytophthora sojae (a hemibiotrophic Oomycete pathogen), Generally, a higher than basal endogenous ABA concentration within plant tissues at the time of avirulent pathogen inoculation, caused an interaction shift towards what phenotypically resembled susceptibility. Conversely, a lower than basal endogenous ABA concentration in plants inoculated with a virulent pathogen caused a shift towards resistance. An extensive suppressive effect of ABA on defence responses was revealed by a range of techniques that included histochemical, biochemical and molecular approaches. A universal effect of ABA on suppression or induction of the phenylpropanoid pathway via regulation of the key entry point gene, phenylalanine ammonia-lyase (PAL), when stimulated by biotic or abiotic elicitors was shown. ABA also influenced a wide variety of other defence-related components such as: the development of a hypersensitive response (HR), the accumulation of the reactive oxyden species, hydrogen peroxide and the cell wall strengthening compounds lignin and callose, accumulation of SA and the phytoalexin, glyceollin and the transcription of the SA-dependent pathogenesis- related gene (PR-1). The near genome-wide microarray gene expression analysis of an ABA induced susceptible interaction also revealed an yet unprecedented insight into the great diversity of defence responses that were influenced by ABA that included: disease resistance like proteins, antimicrobial proteins as well as phenylpropanoid and tryptophan pathway enzymes. Subtle differences were found in the number and type of defence responses that were regulated by ABA in each type of plant and pathogen interaction that was studied. This thesis has clearly identified in plant/pathogen interactions previously unknown and important roles for ABA in the regulation of many defence responses.
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Zabaras, Dimitrios, University of Western Sydney, of Science Technology and Environment College e of Science Food and Horticulture School. "Determination of induced changes in foliar emissions of terpene-accumulating plants". THESIS_CSTE_SFH_Zabaras_D.xml, 2003. http://handle.uws.edu.au:8081/1959.7/809.
Testo completoAbstract (sommario):
Stress-induced changes in the emissions of volatiles from many economically-important plants have been demonstrated in studies over the past decade. Plants such as cotton and corn change both the composition and concentration of their emissions when subjected to wounding, herbivory and pathogen attack. Terpene-accumulating plants have been overlooked as potential objects of such studies although work on conifers has shown that species rich in constitutive defences can also exhibit induced responses. The aim of this study was to investigate whether terpene-accumulating plants respond to stress by altering their foliar emissions qualitatively and/or quantitatively. Species examined included Salvia officinalis (common sage), Melaleuca alternifolia (Australian tea tree) and Ocimum minimum (Bush basil). An experimental design was developed to eliminate factors such as leaf ontogeny that can affect the obtained results and complicate their interpretation. Small-scale solvent extraction and HS-SPME-based techniques were also developed; they enabled the quantitative determination of treatment-induced changes over periods ranging from 10 minutes to 6 months. Treatment of plants included mechanical wounding, herbivory, pathogen attack and chemical elicitation. Overall, statistically significant induced-changes were observed for both leaf-oil composition and concentration. The response of the different species used varied. O. minimum exhibited the greatest compositional changes whilst M. alternifolia was the only species for which oil-concentration changes were observed. The demonstrated changes were not as great as those reported in similar studies with non-terpene producing plants. The results indicate that the high metabolic costs associated with the production and storage of constitutive defences may be responsible for the limited induction of further defensive responsesDoctor of Philosophy (PhD)
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Jabeen, Aslam Asifa [Verfasser], e Elisabeth [Akademischer Betreuer] Magel. "Stress responses of black locust (Robinia pseudoacacia L.) to drought and/or pathogen attack / Asifa Jabeen Aslam. Betreuer: Elisabeth Magel". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2015. http://d-nb.info/1078358389/34.
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Mahmood, Seham Ahmed. "The role of extensin cell wall proteins in the resistance of potato (Solanum tuberosum L. cv. Desiree) to pathogen attack". Thesis, Bangor University, 2016. https://research.bangor.ac.uk/portal/en/theses/the-role-of-extensin-cell-wall-proteins-in-the-resistance-of-potato-solanum-tuberosum-l-cv-desiree-to-pathogen-attack(93b6a6c6-d77b-49f9-8fc7-e2abe66d8bdf).html.
Testo completoAbstract (sommario):
Potato (Solanum tuberosum L.) is one of the most economically important crops worldwide for both consumers and farmers; however, it is subjected to huge losses as a result of bacterial, viral and fungal attacks. Therefore, genetic engineering is being used to generate potato crops that are resistant to herbicides, insects and pathogens. It is becoming increasingly apparent that the proteins of the plant cell wall play an important role in the defence of plants against pathogen attacks. Recent studies showed that overexpression of an extensin gene in Arabidopsis conferred considerable resistance to bacterial pathogen attacks. The key objective of this work was to transform Solanum tuberosum L. cv. Desiree potato plants with the Arabidopsis extensin atExt1 gene under the transcriptional control of the strong constitutive CaMV 35S promoter. Stable transformation of the potato genotype Desiree with atExt1 genes was achieved by an Agrobacterium-mediated transformation. The current research also studied the defence response of the overexpressed atExt1 transgenic potato plants by infecting them with Pseudomonas syringae DC3000 and Pectobacterium carotovorum pathogens; and, symptom development was monitored. To investigate if the expression levels of the atExt1 gene in transgenic potato lines have different responses to pathogen infection, two lines of atExt1 transgenic potatoes were tested: the high-level overexpressed atExt1 transgenic line (the transgenic H line) and the low-level overexpressed atExt1 transgenic line (the transgenic L line). This analysis of extensin proteins in plant defence responses provided further evidence to their real function. Pathogenesis analysis within the transgenic H lines showed that the formation of disease symptoms was restricted by inhibiting the colonisation of the pathogens compared with both wild-type potato plants and in the transgenic L line. Furthermore, basal defences and signal transduction pathways involved in plant defence were not perturbed in the transgenic potato lines, as shown by an analysis of the expression of PR-1 and defensin genes. These results show that extensin overexpression in transgenic H potato plants limits pathogen attacks. This is the first study to generate the overexpression of the atExt1 extensin gene in transgenic potato plants and to examine the response of these transgenic lines to bacterial pathogen invasion.
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Gatsukovich, Yulia. "Characterization of Eukaryotic Translation Initiation Factor 5A-2 (eIF5A-2) in Arabidopsis thaliana: Effects of Wounding and Pathogen Attack". Thesis, Waterloo, Ont. : University of Waterloo, 2004. http://etd.uwaterloo.ca/etd/ygatsuko2004.pdf.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--University of Waterloo, 2004."A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Science in Biology." Includes bibliographical references.
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Sun, Chao [Verfasser], Ralf [Akademischer Betreuer] Oelmüller, Jutta [Akademischer Betreuer] Ludwig-Müller e Axel [Akademischer Betreuer] Mithöfer. "The beneficial fungus Piriformospora indica confers tolerance to plants under drought stress and pathogen attack / Chao Sun. Gutachter: Ralf Oelmüller ; Jutta Ludwig-Müller ; Axel Mithöfer". Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2015. http://d-nb.info/1069105392/34.
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Quilliam, Richard S. "The role of cell wall invertase activity in source-sink relations in vegetative tissues of Arabidopsis thaliana and in response to wounding and pathogen attack". Thesis, University of Sheffield, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.752717.
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Inglese, Steven J. "Tolerance of Senecio vulgaris attacked by a native and an alien pathogen". Thesis, Lancaster University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435880.
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Meela, Moraba Macdonald. "Evaluation of alien invasive weedy plants for activity against plant pathogenic fungi". Diss., University of Pretoria, 2009. http://hdl.handle.net/2263/23195.
Testo completoAbstract (sommario):
Plant fungal pathogens are a major threat to food security worldwide. The most important method of protecting plants against fungal attack is the use of fungicides, but the development of resistance towards synthetic fungicides is of great concern. Moreover, the health risks associated with the use of chemical fungicides increase the need to search for safe, efficacious and environmentally friendly fungicides. Plants produce antifungal agents by secondary metabolism to protect themselves from fungal attack, and therefore many plant species have substantial antifungal activity. The use of plant extracts could enable the development of inexpensive and environmentally acceptable fungicides based on locally available natural products. This study was undertaken to investigate weedy and invasive plant species for antifungal activity against plant pathogens in order to develop a useful product using a widely available resource. Acetone leaf extracts of seven invasive species (Chromoleana odorata, Ipomoea alba, Tecoma stans, Passiflora suberosa, Passiflora subpeltata, Aristolochia sp, Solanum seaforthianum) were screened against eight plant fungal pathogens viz Rhizoctonia solani, Fusarium oxysporium, Penicillum janthinellum, Penicillum expansum, Aspergillus parasiticus, Aspergillus niger, Pythium ultimum and Phytophthora nicotiana, using microdilution assay and bioautography. The acetone extract of Tecoma stans had reasonable antifungal activity with an average minimal inhibitory concentration (MIC) value against all the fungi of 550 ìg/ml and clear zones on bioautograms indicating inhibition of fungal growth of a compounds with an Rf of 0.082 in BEA against several of the fungal pathogens. Due to the clear compound on bioautography and availability of Tecoma stans, this species was selected for further work. Bioassay-guided fractionation of the leaves of the Tecoma stans dichloromethane (DCM) extract obtained from solvent-solvent fractionation resulted in one major compound, oleanolic acid. The isolated compound had antifungal activity with an average MIC value of 130 ìg/ml against the 10 plant pathogenic fungi and clear bands with an Rf value of 0.082 on bioautograms, indicating fungal growth inhibition. It was surprising that the MIC value of the crude DCM extract was as high as that of the only compound with antifungal activity based on bioautography. These results clearly indicated the possibility of synergisms especially since the average total activity of the extract was nearly 6.5 times higher than that of oleanolic acid with total activity values of 60154 ml for the extract and 9262 ml for oleanolic acid. Cellular cytotoxicity of DCM extract and oleanolic acid was investigated using tetrazoliumbased colorimetric assay (MTT) on Vero monkey kidney cells. The toxicity of the extract and oleanolic acid was determined by LC50 values. The DCM extract and oleanolic acid were toxic with and LC50 of 0.413 mg/ml and 0.129 mg/ml respectively, lower than that of berberine the toxic compound used as control. However therapeutic index which can be defined here as the LC50 in (ìg/ml)/MIC in (ìg/ml), indicated that though the extract and oleanolic acid were toxic, they could be used under controlled conditions against infections of certain of the fungal pathogens. The crude extract had a high therapeutic index value of 21 against microorganisms T. harzianum, R. solani, F. oxysporium and P. expansum; and oleanolic acid had high therapeutic index values of 16 and 64 of against T. harzianum and R.solani respectively. This high therapeutic index value of crude extract and oleanolic acid means that, crude extract and oleanolic acid may be used for treatment of infections by these tested fungi with very little toxicity under controlled conditions. Oleanolic acid had very low antibacterial activity (MIC >250 ìg/ml). against two Grampositive (Staphylococcus aureus, ATCC 29213 and Enterococcus faecalis, ATCC 29212) and two Gram-negative bacteria (Escherichia coli, ATCC 27853 and Pseudomonas aeruginosa, ATCC 25922). Animal pathogenic fungi were more resistant than the plant fungal pathogens. Based on the good activity of the DCM crude extract, the surprising selectivity in activity against different fungi coupled with reasonably good therapeutic indexes and the wide availability of T stans leaves opens up the possibility that a commercial product to protect plants against certain pathogens may be developed from T. stans leaves. CopyrightDissertation (MSc (Veterinary Science))--University of Pretoria, 2008.
Paraclinical Sciences
unrestricted
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"INVESTIGATING THE ROLES OF PHENYLPROPANOID PATHWAY IN PLANT DEFENSE AGAINST PATHOGEN ATTACK". Thesis, 2012. http://hdl.handle.net/10388/ETD-2012-11-788.
Testo completoAbstract (sommario):
The plant phenylpropanoid pathway is initiated from deamination of phenylalanine to form cinnamic acid followed by hydroxylation and methylation of the aromatic ring to generate a variety of phenolic compounds including lignin monomers, flavonoid compounds and sinapate esters. The incorporation of phenylpropanoid metabolism served as a key step in the early land-colonization of plants from aqueous environment since phenolic compounds play important roles in plant development and abiotic/biotic stress responses. Lignin is a heteropolymer of hydroxycinnamyl alcohols that are derived from the major branch of plant phenylpropanoid pathway. The main function of lignin is to enhance the strength of plant cell wall and waterproof the vascular system for long-distance transportation of water and solutes. In addition, lignin is also involved in protecting plants against pathogen attack. My Ph.D. research is to investigate how lignin biosynthesis contributes to plant immunity. The results showed that the expression of major lignin biosynthetic genes was induced upon host fungal pathogen infection. Moreover, a mutant disrupted in the lignin gene F5H1 showed enhanced susceptibility when challenged with several fungal pathogens. F5H1 encodes a ferulic acid 5-hydroxylase that is uniquely present in angiosperm plants, leading to the biosynthesis of syringyl lignin monomer, which is not present in gymnosperm plants. Subsequent research demonstrated that f5h1 mutation impaired the penetration (pre-invasion) resistance but did not impact post-invasion resistance. Furthermore, the pathogen-induced expression of lignin genes was independent of well-characterized defensive signaling pathways, and regulated by a novel regulating mechanism. F5H1 contributes to pmr2-mediated resistance but acts independently of other molecular components of penetration resistance including PEN1, PEN2, and PEN3. In contrast to f5h1, a knockout mutant of flavonoid pathway gene chalcone isomerase (CHI/TT5) showed enhanced resistance to host anthracnose pathogen Colletotrichum higginsianum in a salicylic acid (SA)-dependent manner. Taken together, our results for the first time provide genetic evidence demonstrating that lignin biosynthetic gene F5H1 plays critical roles in plant penetration resistance and that an uncharted pathway in flavonoid metabolism confers an SA-dependent resistance pathway in Arabidopsis.
Libri sul tema "Pathogen attack"
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G, Ayres P., a cura di. Pests and pathogens: Plant responses to foliar attack. Oxford, UK: Bios Scientific Publishers, 1992.
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Plant defense: Warding off attack by pathogens, pests and vertebrate herbivores. Chichester, West Sussex, U.K: Wiley-Blackwell, 2011.
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Kowalski, Kathiann M. Attack of the superbugs: The crisis of drug-resistant diseases. Berkeley Heights, NJ: Enslow Publishers, 2005.
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Walters, Dale. Physiological Responses of Plants to Attack. Wiley & Sons, Incorporated, John, 2015.
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Walters, Dale. Physiological Responses of Plants to Attack. Wiley & Sons, Incorporated, John, 2015.
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Walters, Dale. Physiological Responses of Plants to Attack. Wiley-Interscience, 2015.
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Walters, Dale. Plant Defense: Warding off Attack by Pathogens, Herbivores and Parasitic Plants. Wiley & Sons, Incorporated, John, 2011.
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Walters, Dale. Plant Defense: Warding off Attack by Pathogens, Herbivores and Parasitic Plants. Wiley & Sons, Incorporated, John, 2011.
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Ayres, P. g. Pests and Pathogens: Plant Responses to Foliar Attack (Environmental Plant Biology Series). Garland Science, 1992.
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Matiello, Marcelo, e Tamara B. Kaplan. A Mother Who Could Not See Her Baby. A cura di Angela O’Neal. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190609917.003.0027.
Testo completoAbstract (sommario):
Neuromyelitis optica spectrum disorders (NMOSD) belong to a group of relapsing neurological syndromes characterized by significant morbidity and mortality due to central nervous system (CNS) inflammation and necrosis. Most patients are seropositive for pathogenic antibodies targeting Aquaporin-4, and while this water channel is mostly expressed on the foot processes of astrocytes, it is also expressed in placental tissues. On planning a pregnancy, patients should be well informed about the increased risk of preeclampsia and miscarriages, and that most medications used to treat NMOSD have potentially severe toxicities to the fetus. There is also increased risk of relapses in the postpartum period, and immunosuppressive agents are the mainstream method of preventing attacks.
Capitoli di libri sul tema "Pathogen attack"
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Ghosh, Srayan, Kamal Kumar Malukani, Ravindra Kumar Chandan, Ramesh V. Sonti e Gopaljee Jha. "How Plants Respond to Pathogen Attack: Interaction and Communication". In Sensory Biology of Plants, 537–68. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8922-1_20.
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Prusky, Dov, Shiri Barad, Neta Luria e Dana Ment. "pH Modulation of Host Environment, a Mechanism Modulating Fungal Attack in Postharvest Pathogen Interactions". In Post-harvest Pathology, 11–25. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07701-7_2.
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Cooper, W., M. Bouzayen, C. Barry, A. J. Hamilton, S. Rossall e D. Grierson. "Molecular and Physiological Characterisation of the Role of Ethylene during Pathogen Attack of Tomato Fruit". In Cellular and Molecular Aspects of the Plant Hormone Ethylene, 259–60. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-1003-9_60.
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Ernst, D., M. Jürgensen, G. Bahnweg, W. Heller e G. Müller-Starck. "Common Links of Molecular Biology with Biochemistry and Physiology in Plants Under Ozone and Pathogen Attack". In Growth and Defence in Plants, 29–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30645-7_2.
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Wentz, Travis G., Lijun Hu, Thomas S. Hammack, Eric W. Brown, Shashi K. Sharma e Marc W. Allard. "Next Generation Sequencing for the Detection of Foodborne Microbial Pathogens". In Defense Against Biological Attacks, 311–37. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-03071-1_14.
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Kratz, Thomas, Bruria Adini, August Stich e René Gottschalk. "Clinical Management of Patients Infected with Highly Pathogenic Microorganisms". In Defense Against Biological Attacks, 171–94. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-03053-7_9.
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Pedras, M. Soledade C. "Fungal Attack and Cruciferous Defenses: Tricking Plant Pathogens". In The Biological Activity of Phytochemicals, 127–39. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7299-6_9.
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Schweizer, Patrick. "Host and Nonhost Response to Attack by Fungal Pathogens". In Biotechnological Approaches to Barley Improvement, 197–235. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-44406-1_11.
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Pinhey, Sally, e Margaret Tebbs. "The role of fungi." In Plants for soil regeneration: an illustrated guide, 23–27. Wallingford: CABI, 2022. http://dx.doi.org/10.1079/9781789243604.0005.
Testo completoAbstract (sommario):
Abstract This chapter focuses on the role of fungi. Fungi are a vital part of the mixture of microorganisms found in healthy soil. Fungal associations between plant roots and beneficial fungi are known as mycorrhizae (meaning 'fungus' and 'root'), and form a beneficial or symbiotic relationship with plants growing in the soil. Mycorrhizal fungi also facilitate plant interactions with other soil microbes. These include pathogens, and bacteria that produce vitamins and protect against attack. The most common of the mycorrhizae are divided into the following: (1) ectomycorrhizae; (2) endomycorrhizae; (3) arbuscular mycorrhizae; (4) ericoid mycorrhizae; and (5) orchid mycorrhiza. The role of saprophytes, pathogens and actinomycetes are also discussed.
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Kobayashi, Issei, e Yuhko Kobayashi. "Plant Actin Cytoskeletal Responses to Attack and Invasion by Pathogenic Fungi". In Actin: A Dynamic Framework for Multiple Plant Cell Functions, 573–85. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-015-9460-8_32.
Testo completoAtti di convegni sul tema "Pathogen attack"
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Kobayashi, Takako, Wataru Miyazaki, Kazukiyo Yamamoto, Yuji Miura e Takeo Kondo. "A Conceptual Design on the BSL-4 Location and Management". In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49512.
Testo completoAbstract (sommario):
In the event of an outbreak of an infectious disease, the pathogen of which is highly contagious, or when there are patients suspected to be infected with such a pathogen, it is essential to start treating the patients and controlling infection immediately. As the transportation system has been well developed, there are more worries about terrorist attacks using biological agents now than ever before. It is a real possibility that even the most dangerous pathogens that are the causes of Class 1 infectious diseases specified in the Infectious Diseases Act, such as hemorrhagic fever or smallpox, be brought into Japan. Those most dangerous pathogens can be dealt with only by special laboratories that satisfy BSL-4 (Bio-Safety Level 4) specified by WHO (BSL-4 laboratories)(1). As there are no BSL-4 laboratories in operation in Japan at present, it is an immediate requirement to develop a suitable environment for the operation of laboratories of this kind, in order to maintain effective health risk management for the Japanese people. In this research, in order to put BSL-4 laboratories in operation in Japan, we will clarify what relevant environmental factors are in different types of possible locations. Based on that, we will propose to utilize those laboratories not only in emergencies, but also in normal times. We will also discuss the necessary conditions in the social environment of contemporary Japan for BSL-4 laboratories’ operation.
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Dima, Milica, Aurelia Diaconu, Reta Drăghici, Alina-Nicoleta Paraschiv e Coteț Gheorghe. "RESEARCHES ON REPORTING THE ATTACK OF SOME PEANUTS DISEASES CULTIVATED ON SANDY SOILS". In GEOLINKS Conference Proceedings. Saima Consult Ltd, 2021. http://dx.doi.org/10.32008/geolinks2021/b1/v3/41.
Testo completoAbstract (sommario):
Peanuts (Arachis hypogaea L.) are widely grown as a food and oleaginous species. Cultivation of peanuts offers important economic benefits, but one of the most important challenges that growers confront is the fight against destructive diseases. Culture is susceptible to a variety of pathogens, such as bacteria, fungi, viruses, and nematodes, resulting in low yields and degradation of grain quality. Among the most devastating fungal diseases of peanuts are Cercospora arachidicola, Puccinia arachidis, Sclerotium rolfsii which cause substantial loss of production. Loss of yields due to the incidence of peanut disease may be up to 50%. Fungicides can be used to combat fungal diseases, but there are alternative disease control options, such as cultural practices, cultivation of resistant varieties, which can be useful in combating diseases by reducing the frequency of application of fungicides.
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Lencautan, M. "Determinarea nivelului de rezistenţă a genotipurilor contra atacul bolilor principale a materialului genetic de ameliorare a culturilor leguminoase pe fonduri naturale şi artificiale de infecţie". In International Scientific Symposium "Plant Protection – Achievements and Prospects". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2020. http://dx.doi.org/10.53040/9789975347204.69.
Testo completoAbstract (sommario):
In the soil and climatic conditions of the Republic of Moldova, legume crops are attacked by a complex of harmful species, which present a danger in decreasing the level of plant productivity. To solve the problem of increasing the level of production, the basic factor is to estimate highly productive varieties (hybrids), adopted under stressful environmental conditions endowed with high levels of resistance to harmful pathogens can later be used in the process of plant improvement as initial genetic material.
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Khalil Bhuiyan, Md Ebrahim, Dustin Smith, Eric J. Voss, Chin-Chuan Wei e Mohammad Shavezipur. "Surface Functionalization of Silicon MEMS Biochemical Sensors for the Detection of Foodborne Pathogens". In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-69708.
Testo completoAbstract (sommario):
Abstract This work presents the surface modification of silicon chips as a platform for silicon-based biosensors with applications aiming for the detection of foodborne bacteria in aqueous solution. The detection requires high selectivity as the solution may contain a variety of biological species, which affect the outcome of the sensing process. The silicon surface is functionalized by a self-assembled monolayer (SAM) with thiol groups followed by immobilizing a thiol-linked DNA aptamer. The DNA aptamer used in this work has reported to recognize a biological species, E. coli ATCC 25922. The presence of DNA aptamer on the sensor surface allows the capture of the specific E. coli cells on the surface, while other potential biological (and chemical) species would not attach to the sensor surface, thus improving the selectivity of the sensor. The uniform formation of the SAM on the surface is an important step toward uniformly coating the sensor surface with the desired DNA aptamer. The SAM is created on the silicon surface by surface modification with the MPTS (3-mercaptopropyl trimethoxy silane) solution. Then the aptamer DNA solution is applied as droplets on the chip followed by a cure process. The attachment of the SAM and DNA aptamers are verified by atomic force microscopy (AFM). The surface functionalization presented in this work can be used for sensors made of silicon coated with a thin layer of native oxide, and can be adopted for detection of other cells and biological agents using the proper SAM and DNA aptamer.
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Bataeva, Yulya, Damelya Magzanova, Adelia Baimukhambetova, Lilit Grigoryan e Daria Vilkova. "Influence of Bacillus megaterium to promote growing of cotton (Gossypium Hirsutum L.)". In "The Caspian in the Digital Age" within the framework of the International Scientific Forum "Caspian 2021: Ways of Sustainable Development". Dela Press Publishing House, 2022. http://dx.doi.org/10.56199/dpcsebm.momz3523.
Testo completoAbstract (sommario):
The article presents the results of studying the influence of Bacillus megaterium on the growth and development of Gossypium hirsutum cotton plant in the field conditions of the Astrakhan Region. In the wild plants have to cope with several adverse environmental conditions, such as water scarcity, high salt concentrations in the soil, extreme temperatures, nutrient deficiencies and pathogen attacks. However, plants can interact with several soil microorganisms, including plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi, which make the plant more resistant to such stresses. Bacillus-based products represent the most important class of microbial products for phytosanitary use available on the market. Field studies and microbiological analysis of the soil were carried out on the basis of the All-Russian Research Institute of Irrigated Horticulture and Melon Growing (VNIIOB) and Astrakhan State University. To compare the results, in the experiment the chemical mineral fertilizer Amofoska was used in the concentration of the working solution. Distilled water was used as a control substance. The weight of the crop was calculated at the end of the vegetation season. The research revealed that Bacillus megaterium has growth-promoting effect on cotton culture. Germination of seeds treated with bacillus was 96%. Plant biometrics indicate that plants treated with bacillus show the highest values in terms of leaf weight, leaf area and root length relative to the control. Thus, the number of buds and flowers increased by 5.1 and 3.1 pieces in comparison to the control sample and the one treated with mineral fertilizer, respectively. The length of the root also increased by 9.8 and 2.4 cm. The weight of cotton treated with bacillus exceeds the control variant by 46 g. and mineral fertilizer by 48.4 g, respectively. When abundantly poured for the second time, this indicator exceeded the weight of the control sample by 8 g and after treatment with mineral fertilizer - by 32 g.
Rapporti di organizzazioni sul tema "Pathogen attack"
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Prusky, Dov, Lisa Vaillancourt e Robert Fluhr. Host Ammonification by Postharvest Pathogens and its Contribution to Fungal Colonization and Symptom Development. United States Department of Agriculture, dicembre 2006. http://dx.doi.org/10.32747/2006.7592640.bard.
Testo completoAbstract (sommario):
Postharvest decay of fruits and vegetables caused by pathogenic and saprophytic fungi significantly impairs the quality and quantity of fresh produce brought to market. Consequently, there is considerable interest in identifying factors that determine the susceptibility of these commodities to pathogen infection. Insidious postharvest decays remain quiescent during fruit growth and harvest, but activate during the postharvest period. A key response to the physiological changes occurring during fruit ripening is the initiation of ammonium secretion by the pathogen. Ammonium ions at the infection site (ammonification) have subsequent effects on both the pathogen and the host. An accompanying alkalinization process resulting from ammonia accumulation contributes to pathogenicity, since some important fungal virulence factors, (such as pectate lyase in Colletotrichum sp.), are significantly expressed only under alkaline conditions. In this proposal, investigated the mechanisms by which ammonification and alkalinization of infected tissues by the pathogen affect the host’s defense response to fungal attack, and instead increase compatibility during postharvest pathogen-host interactions. Our hypotheses were:1) that host signals, including ripening-related changes, induce secretion of ammonia by the pathogen; 2) that ammonia accumulation, and the resultant environmental alkalinization regulate the expression of fungal virulence genes that are essential for postharvest rot development; 3) that ammonification enhanced fungal colonization, by “suppression of host responses”, including production of reactive oxygen species, activation of superoxide, and polyphenol oxidase production. Our objectives were: to analyze: 1) factor(s) which activate the production and secretion of ammonia by the fungus; 2) fungal gene(s) that play role(s) in the ammonification process; 3) the relationship between ammonification and the activation of host defense response(s) during pathogen colonization; and 4) analyze hostgene expression in alkalinized regions of fruits attacked by hemibiotrophic fungi.
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Harms, Nathan, Judy Shearer, James Cronin e John Gaskin. Geographic and genetic variation in susceptibility of Butomus umbellatus to foliar fungal pathogens. Engineer Research and Development Center (U.S.), agosto 2021. http://dx.doi.org/10.21079/11681/41662.
Testo completoAbstract (sommario):
Large-scale patterns of plant invasions may reflect regional heterogeneity in biotic and abiotic factors and genetic variation within and between invading populations. Having information on how effects of biotic resistance vary spatially can be especially important when implementing biological control because introduced agents may have different Impacts through interactions with host-plant genotype, local environment, or other novel enemies. We conducted a series of field surveys and laboratory studies to determine whether there was evidence of biotic resistance, as foliar fungal pathogens, in two introduced genotypes (triploid G1, diploid G4) of the Eurasian wetland weed, Butomus umbellatus L. in the USA. We tested whether genotypes differed in disease attack and whether spatial patterns in disease incidence were related to geographic location or climate for either genotype. After accounting for location (latitude, climate), G1 plants had lower disease incidence than G4 plants in the field (38% vs. 70%) but similar pathogen richness. In contrast, bioassays revealed G1 plants consistently received a higher damage score and had larger leaf lesions regardless of pathogen. These results demonstrate that two widespread B. umbellatus genotypes exhibit different susceptibility to pathogens and effectiveness of pathogen biological controls may depend on local conditions.
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Avni, Adi, e Kirankumar S. Mysore. Functional Genomics Approach to Identify Signaling Components Involved in Defense Responses Induced by the Ethylene Inducing Xyalanase Elicitor. United States Department of Agriculture, dicembre 2009. http://dx.doi.org/10.32747/2009.7697100.bard.
Testo completoAbstract (sommario):
Plant-microbe interactions involve a large number of global regulatory systems, which are essential for plants to protect themselves against pathogen attack. An ethylene-inducing xylanase (EIX) of Trichoderma viride is a potent elicitor of plant defense responses, like hypersensitive response (HR), in specific cultivars of tobacco (Nicotiana tabacum) and tomato (Lycopersicon esculentum). The central goal of this proposal was to investigate the molecular mechanisms that allow plants to specifically activate defense responses after EIX treatment. We proposed to identify cellular signaling components involved in the induction of HR by the EIX elicitor. The molecular genetic analysis of the signal transduction pathway that modulates hypersensitive responses is an important step in understanding the induction of plant defense responses. The genes that mediate LeEIX2-EIX dependent activation of resistance mechanisms remain to be identified. We used two approaches to identify the cellular signaling components that induce HR mediated by the EIX elicitor. In the first approach, we performed a yeast two-hybrid screening using LeEix2 as bait to identify plant proteins that interact with it. In the second approach, we used virus-induced gene silencing (VIGS) for a high-throughput screen to identify genes that are required for the induction of LeEIX2-EIX mediated HR. VIGS will also be used for functional characterization of genes that will be identified during the yeast two-hybrid screen. This investigation will shed light on cellular processes and signaling components involved in induction of general plant defense against pathogens and will provide the basis for future biotechnological approaches to improve plant resistance to pathogens. Several genes were indentified by the two approaches. We used the VIGS and yeast two hybrid approaches to confirm that activity of the genes initially identified by different procedure. Two genes inhibit the induction of HR by the fungal elicitor in the different systems; Tobacco-Harpin binding protein 1 and cyclopropyl isomerase.
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Prusky, Dov, Noel T. Keen e Stanley Freeman. Elicitation of Preformed Antifungal Compounds by Non-Pathogenic Fungus Mutants and their Use for the Prevention of Postharvest Decay in Avocado Fruits. United States Department of Agriculture, gennaio 1996. http://dx.doi.org/10.32747/1996.7570573.bard.
Testo completoAbstract (sommario):
C. gloeosporioides attacks unripe avocado fruits in the orchard. Germinated spores produce appressoria that germinate and breach the cuticle, but the resultant subcuticular hyphae become quiescent and do not develop further until fruit is harvested and ripens. Resistance of unripe avocado to attach by C. gloeosporioides is correlated with the presence of fungitoxic concentrations of the preformed antifungal compound, 1-acetoxy-2-hydroxy-4-oxoheneicosa-12, 15 diene in the pericarp of unripe fruits. The objective of this proposal was to study the signal transduction process by which elicitors induce resistance in avocado. It was found that abiotic elicitors, infection of avocado fruit with C. gloeosporioides or treatment of avocado cell suspension with cell-wall elicitor induced a significant production of reactive oxygen species (ROS). Ripe and unripe fruit tissue differ with regard to the ROS production. The unripe, resistant fruit are physiologically able to react and to produce high levels of ROS and increased activity of H+ATPase that can enhance the phenylpropanoid pathway ad regulate the levels of the antifungal compound-diene, inhibit fungal development, resulting in its quiescence. Interestingly, it was also found that growth regulators like cytokinin could do activation of the mechanism of resistance. Postharvest treatments of cytokinins strongly activated the phenylpropanoid pathway and induce resistance. We have developed non-pathogenic strains of C. gloeosporioides by Random Enzyme Mediated Integration and selected a hygromycin resistance, non-pathogenic strain Cg-142 out of 3500 transformants. This non-pathogenic isolate activates H+ATPase and induces resistance against Colletotrichum attack. As a basis for studying the importance of PL in pathogenicity, we have carried out heterologous expression of pel from C. gloeosporioides in the non-pathogenic C. magna and determine the significant increase in pathogenicity of the non-pathogenic strain. Based on these results we can state that pectate lyase is an important pathogenicity factor of C. gloeosporioides and found that fungal pathogenicity is affected not by pel but by PL secretion. Our results suggest that PH regulates the secretion of pectate lyase, and support its importance as a pathogenicity factor during the attack of avocado fruit by C. gloeosporioides . This implicates that if these findings are of universal importance in fungi, control of disease development could be done by regulation of secretion of pathogenicity factors.
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Fitch, J. Preparing for Terrorist Attacks that Use Next-Generation Pathogens. Office of Scientific and Technical Information (OSTI), gennaio 2005. http://dx.doi.org/10.2172/15014501.
Testo completo
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Sessa, Guido, e Gregory B. Martin. molecular link from PAMP perception to a MAPK cascade associated with tomato disease resistance. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7597918.bard.
Testo completoAbstract (sommario):
The research problem: The detection of pathogen-associated molecular patterns (PAMPs) by plant pattern recognition receptors (PRRs) is a key mechanism by which plants activate an effective immune response against pathogen attack. MAPK cascades are important signaling components downstream of PRRs that transduce the PAMP signal to activate various defense responses. Preliminary experiments suggested that the receptor-like cytoplasmickinase (RLCK) Mai5 plays a positive role in pattern-triggered immunity (PTI) and interacts with the MAPKKK M3Kε. We thus hypothesized that Mai5, as other RLCKs, functions as a component PRR complexes and acts as a molecular link between PAMP perception and activation of MAPK cascades. Original goals: The central goal of this research was to investigate the molecular mechanisms by which Mai5 and M3Kε regulate plant immunity. Specific objectives were to: 1. Determine the spectrum of PAMPs whose perception is transmitted by M3Kε; 2. Identify plant proteins that act downstream of M3Kε to mediate PTI; 3. Investigate how and where Mai5 interacts with M3Kε in the plant cell; 4. Examine the mechanism by which Mai5 contributes to PTI. Changes in research directions: We did not find convincing evidence for the involvement of M3Kε in PTI signaling and substituted objectives 1 and 3 with research activities aimed at the analysis of transcriptomic profiles of tomato plants during the onset of plant immunity, isolation of the novel tomato PRR FLS3, and investigation of the involvement of the RLCKBSKs in PTI. Main achievements during this research program are in the following major areas: 1. Functional characterization of Mai5. The function of Mai5 in PTI signaling was demonstrated by testing the effect of silencing the Mai5 gene by virus-induced gene silencing (VIGS) experiments and in cell death assays. Domains of Mai5 that interact with MAPKKKs and subcellular localization of Mai5 were analyzed in detail. 2. Analysis of transcriptional profiles during the tomato immune responses to Pseudomonas syringae (Pombo et al., 2014). We identified tomato genes whose expression is induced specifically in PTI or in effector-triggered immunity (ETI). Thirty ETI-specific genes were examined by VIGS for their involvement in immunity and the MAPKKK EPK1, was found to be required for ETI. 3. Dissection of MAP kinase cascades downstream of M3Kε (Oh et al., 2013; Teper et al., 2015). We identified genes that encode positive (SGT and EDS1) and negative (WRKY1 and WRKY2) regulators of the ETI-associated cell death mediated by M3Kε. In addition, the MKK2 MAPKK, which acts downstream of M3Kε, was found to interact with the MPK3 MAPK and specific MPK3 amino acids involved interaction were identified and found to be required for induction of cell death. We also identified 5 type III effectors of the bacterial pathogen Xanthomonaseuvesicatoria that inhibited cell death induced by components of ETI-associated MAP kinase cascades. 4. Isolation of the tomato PRR FLS3 (Hind et al., submitted). FLS3, a novel PRR of the LRR-RLK family that specifically recognizes the flagellinepitope flgII-28 was isolated. FLS3 was shown to bind flgII-28, to require kinase activity for function, to act in concert with BAK1, and to enhance disease resistance to Pseudomonas syringae. 5. Functional analysis of RLCKs of the brassinosteroid signaling kinase (BSK) family.Arabidopsis and tomato BSKs were found to interact with PRRs. In addition, certain ArabidospsisBSK mutants were found to be impaired in PAMP-induced resistance to Pseudomonas syringae. Scientific and agricultural significance: Our research activities discovered and characterized new molecular components of signaling pathways mediating recognition of invading pathogens and activation of immune responses against them. Increased understanding of molecular mechanisms of immunity will allow them to be manipulated by both molecular breeding and genetic engineering to produce plants with enhanced natural defense against disease.
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Freeman, Stanley, e Daniel Legard. Epidemiology and Etiology of Colletotrichum Species Causing Strawberry Diseases. United States Department of Agriculture, settembre 2001. http://dx.doi.org/10.32747/2001.7695845.bard.
Testo completoAbstract (sommario):
Diseases caused by Colletotrichum spp. are one of the most important limitations on international strawberry production, affecting all vegetative and fruiting parts of the plant. From 1995 to 1997, C. acutatum infections reached epidemic levels in Israeli strawberry nurseries, causing extensive loss of transplants in fruit-bearing fields and additional reductions in yield. Although C. acutatum also occurs on strawberry in Florida, recent crown rot epidemics have been primarily caused by C. gloeosporioides. Little is known about the basic epidemiology of these important diseases on strawberry. The source of initial inoculum for epidemics in Israel, Florida (other US states including California) and the rest of the world is not well understood. Subspecies relationships between Colletotrichum isolates that cause the different diseases on strawberry (i.e. attack different tissues) are also not well understood. Objectives of this proposal were to detennine the potential of infested soil, strawberry debris and other hosts as sources of primary inoculum for strawberry diseases caused by Colletotrichum spp. in Israel and Florida. In addition, traditional (ie. morphological characteristics, benomyl sensitivity, vegetative compatibility grouping) and DNA based methods were used to investigate the etiology of these diseases in order to resolve epidemiologically important subspecies variation. In Israel it was found that C. gloeosporioides and C. acutatum infecting strawberry could remain viable in sterilized soil for up to one year and in methyl-bromide fumigated soil for up to 4 months; inoculum in mummified fruit remained viable for at least 5 months under field conditions whereas that in infected crowns was not recovered. Therefore, the contribution of these inocula to disease epidemics should be considered. The host range and specificity of C. acutatum from strawberry was examined on pepper, eggplant, tomato, bean and strawberry under greenhouse conditions. The fungus was recovered from all plant species over a three-month period but caused disease symptoms only on strawberry. C. acutatum was also isolated from healthy looking, asymptomatic plants of the weed species, Vicia and Conyza, growing in infected strawberry fruiting fields. Isolates of C. acutatum originating from strawberry and anemone infected both plant species in artificial inoculations. The habitation of a large number of plant species including weeds by C. acutatum suggests that although it causes disease only on strawberry and anemone in Israel, these plants may serve as a potential inoculum source for strawberry infection and pennit survival of the pathogen between seasons. In Florida, isolates of Colletotrichum spp. from diseased strawberry fruit and crowns were evaluated to detennine their etiology and the genetic diversity of the pathogens. Only C. acutatum was recovered from fruit and C. gloeosporioides were the main species recovered from crowns. These isolates were evaluated at 40 putative genetic loci using random amplified polymorphic DNA (RAPD). Genetic analysis of RAPD markers revealed that the level of linkage disequilibrium among polymorphic loci in C. gloeosporioides suggested that they were a sexually reproducing population. Under field conditions in Florida, it was detennined that C. gloeosporioides in buried crowns survived
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Chiel, Elad, e Christopher J. Geden. Development of sustainable fly management tools in an era of global warming. United States Department of Agriculture, gennaio 2014. http://dx.doi.org/10.32747/2014.7598161.bard.
Testo completoAbstract (sommario):
House flies (Muscadomestica) are global pests of animal agriculture, causing major annoyance, carrying pathogens among production facilities and humans and thus have profound impacts on animal comfort and productivity. Successful fly control requires an integrated pest management (IPM) approach that includes elements of manure management, mass trapping, biological control, and selective insecticide use. Insecticidal control of house flies has become increasingly difficult due to the rapidity with which resistance develops, even to new active ingredients. Global climate change poses additional challenges, as the efficacy of natural enemies is uncertain under the higher temperatures that are predicted to become more commonplace in the future. The two major objectives of this research project were: 1) to develop a cost-effective autodissemination application method of Pyriproxifen (PPF), an insect growth regulator, for controlling house flies; 2) to study the effect of increasing temperatures on the interactions between house flies and their principal natural enemies. First, we collected several wild house fly populations in both countries and established that most of them are susceptible to PPF, although one population in each country showed initial signs of PPF-resistance. An important finding is that the efficacy of PPF is substantially reduced when applied in cows’ manure. We also found that PPF is compatible with several common species of parasitoids that attack the house fly, thus PPF can be used in IPM programs. Next, we tried to develop “baited stations” in which house flies will collect PPF on their bodies and then deliver and deposit it in their oviposition sites (= autodissemination). The concept showed potential in lab experiments and in outdoor cages trials, but under field conditions the station models we tested were not effective enough. We thus tested a somewhat different approach – to actively release a small proportion of PPF-treated flies. This approach showed positive results in laboratory experiments and awaits further field experiments. On the second topic, we performed two experimental sets: 1) we collected house flies and their parasitoids from hot temperature and mild temperature areas in both countries and, by measuring some fitness parameters we tested whether the ones collected from hot areas are better adapted to BARD Report - Project 4701 Page 2 of 16 heat. The results showed very little differences between the populations, both of flies and parasitoids. 2) A “fast evolution” experiment, in which we reared house flies for 20 generations under increasing temperatures. Also here, we found no evidence for heat adaptation. In summary, pyriproxyfen proved to be a highly effective insect growth regulator for house flies that is compatible with it’s natural enemies. Although our autodissemination stations yielded disappointing results, we documented the proportion of flies in a population that must be exposed to PPF to achieve effective fly control. Both the flies and their principal parasitoids show no evidence for local adaptation to high temperatures. This is an encouraging finding for biological control, as our hypothesis was that the fly would be adapting faster to high temperatures than the parasitoids. BARD Report - Project 4701 Page 3 of 16
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Granot, David, Richard Amasino e Avner Silber. Mutual effects of hexose phosphorylation enzymes and phosphorous on plant development. United States Department of Agriculture, gennaio 2006. http://dx.doi.org/10.32747/2006.7587223.bard.
Testo completoAbstract (sommario):
Research objectives 1) Analyze the combined effects of hexose phosphorylation and P level in tomato and Arabidopsis plants 2) Analyze the combined effects of hexose phosphorylation and P level in pho1 and pho2 Arabidopsis mutants 3) Clone and analyze the PHO2 gene 4) Select Arabidopsis mutants resistant to high and low P 5) Analyze the Arabidopsis mutants and clone the corresponding genes 6) Survey wild tomato species for growth characteristics at various P levels Background to the topic Hexose phosphorylating enzymes, the first enzymes of sugar metabolism, regulate key processes in plants such as photosynthesis, growth, senescence and vascular transport. We have previously discovered that hexose phosphorylating enzymes might regulate these processes as a function of phosphorous (P) concentration, and might accelerate acquisition of P, one of the most limiting nutrients in the soil. These discoveries have opened new avenues to gain fundamental knowledge about the relationship between P, sugar phosphorylation and plant development. Since both hexose phosphorylating enzymes and P levels affect plant development, their interaction is of major importance for agriculture. Due to the acceleration of senescence caused by the combined effects of hexose phosphorylation and P concentration, traits affecting P uptake may have been lost in the course of cultivation in which fertilization with relatively high P (30 mg/L) are commonly used. We therefore intended to survey wild tomato species for high P-acquisition at low P soil levels. Genetic resources with high P-acquisition will serve not only to generate a segregating population to map the trait and clone the gene, but will also provide a means to follow the trait in classical breeding programs. This approach could potentially be applicable for other crops as well. Major conclusions, solutions, achievements Our results confirm the mutual effect of hexose phosphorylating enzymes and P level on plant development. Two major aspects of this mutual effect arose. One is related to P toxicity in which HXK seems to play a major role, and the second is related to the effect of HXK on P concentration in the plant. Using tomato plants we demonstrated that high HXK activity increased leaf P concentration, and induced P toxicity when leaf P concentration increases above a certain high level. These results further support our prediction that the desired trait of high-P acquisition might have been lost in the course of cultivation and might exist in wild species. Indeed, in a survey of wild species we identified tomato species that acquired P and performed better at low P (in the irrigation water) compared to the cultivated Lycopersicon esculentum species. The connection between hexose phosphorylation and P toxicity has also been shown with the P sensitive species VerticordiaplumosaL . in which P toxicity is manifested by accelerated senescence (Silber et al., 2003). In a previous work we uncovered the phenomenon of sugar induced cell death (SICD) in yeast cells. Subsequently we showed that SICD is dependent on the rate of hexose phosphorylation as determined by Arabidopsis thaliana hexokinase. In this study we have shown that hexokinase dependent SICD has many characteristics of programmed cell death (PCD) (Granot et al., 2003). High hexokinase activity accelerates senescence (a PCD process) of tomato plants, which is further enhanced by high P. Hence, hexokinase mediated PCD might be a general phenomena. Botrytis cinerea is a non-specific, necrotrophic pathogen that attacks many plant species, including tomato. Senescing leaves are particularly susceptible to B. cinerea infection and delaying leaf senescence might reduce this susceptibility. It has been suggested that B. cinerea’s mode of action may be based on induction of precocious senescence. Using tomato plants developed in the course of the preceding BARD grant (IS 2894-97) and characterized throughout this research (Swartzberg et al., 2006), we have shown that B. cinerea indeed induces senescence and is inhibited by autoregulated production of cytokinin (Swartzberg et al., submitted). To further determine how hexokinase mediates sugar effects we have analyzed tomato plants that express Arabidopsis HXK1 (AtHXK1) grown at different P levels in the irrigation water. We found that Arabidopsis hexokinase mediates sugar signalling in tomato plants independently of hexose phosphate (Kandel-Kfir et al., submitted). To study which hexokinase is involved in sugar sensing we searched and identified two additional HXK genes in tomato plants (Kandel-Kfir et al., 2006). Tomato plants have two different hexose phosphorylating enzymes; hexokinases (HXKs) that can phosphorylate either glucose or fructose, and fructokinases (FRKs) that specifically phosphorylate fructose. To complete the search for genes encoding hexose phosphorylating enzymes we identified a forth fructokinase gene (FRK) (German et al., 2004). The intracellular localization of the four tomato HXK and four FRK enzymes has been determined using GFP fusion analysis in tobacco protoplasts (Kandel-Kfir et al., 2006; Hilla-Weissler et al., 2006). One of the HXK isozymes and one of the FRK isozymes are located within plastids. The other three HXK isozymes are associated with the mitochondria while the other three FRK isozymes are dispersed in the cytosol. We concluded that HXK and FRK are spatially separated in plant cytoplasm and accordingly might play different metabolic and perhaps signalling roles. We have started to analyze the role of the various HXK and FRK genes in plant development. So far we found that LeFRK2 is required for xylem development (German et al., 2003). Irrigation with different P levels had no effect on the phenotype of LeFRK2 antisense plants. In the course of this research we developed a rapid method for the analysis of zygosity in transgenic plants (German et al., 2003).