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Topic: Appressorium

In the News (Thu 31 Dec 09)

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	Harvey C. Hoch
		Initiation of appressorium formation in Uromyces appendiculatus: Organization of the apex, and the responses involving microtubules and apical vesicles.
		Appressorium formation in response to topographical signals by 27 rust species.
		Kwon, Y. Appressorium fromation in Uromyces appendiculatus: thigmotrophic response of the urediospore germling apex.
	www.nysaes.cornell.edu /pp/faculty/hoch/pubs.html (2412 words)

	Induction of Ca2+-Calmodulin Signaling by Hard-Surface Contact Primes Colletotrichum gloeosporioides Conidia To ...
		the appressorium and that scytalone, an intermediate in melanin
		Germination and appressorium formation were tested on a cover glass surface as described previously (11, 27).
		Cloning of a gene expressed during appressorium formation by Colletotrichum gloeosporioides and a marked decrease in virulence by disruption of this gene.
	jb.asm.org /cgi/content/full/180/19/5144 (4753 words)

	Functional genomics of plant infection by the rice blast fungus Magnaporthe grisea
		M. grisea forms a specialised infection structure called an appressorium which is used to penetrate the tough outer cuticle of rice leaves, allowing the fungus entry to the underlying tissues (Talbot, 2003).
		Turgor is translated into mechanical force and a narrow penetration hypha is formed at the base of the appressorium, puncturing the cuticle We are using a multi-disciplinary approach, involving gene functional analysis, cell biology and analytical biochemistry, to investigate the biology of appressorium-mediated plant infection.
		Appressorium turgor is generated by accumulation of a compatible solute within the appressoria to very high concentrations.
	www.wissenschaft-online.de /gbm/fall04/homepage/abstract_detail.php?artikel_id=841 (381 words)

	Involvement of protein phosphorylation in the induction of appressorium formation in Colletotrichum gloeosporioides by ... (Site not responding. Last check: 2007-10-14)
		Avocado surface wax and the ripening hormone ethylene induce conidial germination and appressorium formation in the avocado pathogen C. gloeosporioides [Glomerella cingulata].
		Calyculin A also caused abnormal differentiation such as the formation of an additional appressorium directly from the initial appressorium and at higher concn the formation of unusual structures.
		These results indicate that protein phosphorylation may be involved in the induction of appressorium formation by the 2 host signals.
	trophort.com /information/data/B01/S73/FLA95INV1031114.html (211 words)

	PDE1 Encodes a P-Type ATPase Involved in Appressorium-Mediated Plant Infection by the Rice Blast Fungus Magnaporthe ...
		An appressorium (Ap) is visible on the leaf surface, and infection hyphae are present throughout the epidermal and mesophyll cell layers (arrowheads).
		An appressorium is visible on the leaf surface (Ap) but has not developed a penetration hypha.
		DeZwaan, T.M., Carroll, A.M., Valent, B., and Sweigard, J.A. Magnaporthe grisea Pth11p is a novel plasma membrane protein that mediates appressorium differentiation in response to inductive surface cues.
	www.plantcell.org /cgi/content/full/13/9/1987 (8167 words)

	Nonpathogenic Strains of Colletotrichum lindemuthianum Trigger Progressive Bean Defense Responses during ...
		In vitro assays for conidial germination, appressorium differentiation, and estimation of appressorium turgor pressure.
		Appressorium maturation is both necessary and sufficient for triggering most plant defense responses.
		Cloning of a gene expressed during appressorium formation by Colletotrichum gloeosporiodes and a marked decrease in virulence by disruption of this gene.
	aem.asm.org /cgi/content/full/71/8/4761 (5409 words)

	CSIRO PUBLISHING - Australian Journal of Botany
		The pattern for spore germination and appressorium formation was similar for the six species studied.
		Each ascospore produced a single germ tube which, in 2-6 hr after germination began, formed an appressorium initial in the form of a swelling at its apex.
		Evidence suggested that while contact with a surface was not necessary to initiate appressorium formation, contact with a grass leaf surface was required for appressoria to develop normally.
	www.publish.csiro.au /nid/65/paper/BT9630117.htm (292 words)

	[No title]
		To understand the role of calcineurin on appressorium formation at molecular level, a gene (MgCNA) encoding calcineurin catalytic subunit was cloned and characterized from M. grisea 70-15.
		Since Ace1p is localized in the cytoplasm of the appressorium and the enzymatic function of Ace1p required for avirulence, we conclude that the signal recognized by resistant rice is not Ace1p itself, but the secondary metabolite produced by Ace1p.
		This force is due to the enormous hydrostatic turgor that accumulates within the appressorium as a result of the high concentrations of glycerol present.
	www.fgsc.net /asil2003/HostParasitePosterAbstracts2003.htm (15382 words)

	MAP Kinase and Protein Kinase A-Dependent Mobilization of Triacylglycerol and Glycogen during Appressorium Turgor ...
		Lipid droplets enlarged during appressorium development (at 48 and 96 hr), but no degradation was observed during this experiment.
		Glycogen degradation, which is similarly regulated within the appressorium at the onset of turgor generation, is used to fuel glycolysis during glycerol accumulation and may contribute to glycerol production by the metabolism of dihydroxyacetone 3-phosphate (DHAP), dihydroxyacetone (DHA), or glyceraldehyde (GAD).
		Glycerol accumulation results in hydrostatic turgor and is translated into the force required for cuticle penetration by reorientation of the cytoskeleton, localized dissolution of the cell wall, and formation of penetration pegs.
	www.plantcell.org /cgi/content/full/12/9/1703 (6922 words)

	Appressorium - Wikipedia, the free encyclopedia
		Look up appressorium in Wiktionary, the free dictionary.
		An appressorium is a flattened, hyphal "pressing" organ, from which a minute infection peg grows and enters the host, using turgor pressure capable of punching through even mylar.
		Fungi that exhibit appressorial formation include the necrotroph Pyrenophora teres.
	en.wikipedia.org /wiki/Appressorium (95 words)

	Hemileia vastatrix
		The authors speculate that this organ may serve as an attachment device in the absence of other adhesive forces or that it may anchor the appressoria from within the stomatal cavity.
		Leaf contours and the collisions of germ tubes led the authors to conclude that ridges of 4 µm or higher induce appressorium formation.
		Brown, J; Whan, J; Kenny, M and Merriman P. The effect of coffee leaf rust on foliation and yield of coffee in Papua New Guinea.
	www.coffeeresearch.org /agriculture/hemileiavastatrix.htm (772 words)

	RESEARCHERS FIND KEY TO SUPPRESSION OF RICE BLAST (Site not responding. Last check: 2007-10-14)
		The group was building on previous research by examining expression of an M. grisea gene needed for the formation of the appressorium.
		The response was specific to the mating type of the fungus, and this finding led them to believe it was a reaction to a pheromone-like substance that kept the appressorium from forming.
		Yeast is one of the best understood of all simple organisms and is a fungus, Beckerman said, which helped the researchers decide that a yeast pheromone might affect appressorium formation in the rice blast fungus.
	agnews.tamu.edu /dailynews/stories/PATH/May1797a.htm (732 words)

	Mycorrhiza Literature Exchange
		Suppressive subtractive hybridization and expressed sequence tag sequencing identified 29 plant genes which are upregulated during the appressorium stage of mycorrhiza establishment between Medicago truncatula J5 (Myc(+)) and Glomus mosseae.
		Expression profiling showed that the genes are activated not only from the appressorium stage up to the fully established symbiosis in the Myc(+) genotype of M. truncatula, but also when the symbionts are not in direct cell contact, suggesting that diffusible fungal molecules (Myc factors) play a role in the induction of a signal-transduction pathway.
		Transcript accumulation in roots of a mycorrhiza-defective Myc(-) dmi3 mutant of M. truncatula is not modified by appressorium formation or diffusible fungal molecules, indicating that the signal transduction pathway is required for a successful G. mosseae-M. truncatula interaction leading to symbiosis development.
	mycorrhiza.ag.utk.edu /latest/latest04/04_12weidm1.htm (221 words)

	Cellular Localization and Role of Kinase Activity of PMK1 in Magnaporthe grisea -- Bruno et al. 3 (6): 1525 -- ...
		A conidium of Xh14 incubated on a glass coverslip for 24 h was stained with Calcofluor and Hoechst 33258 (middle panel) to visualize cell walls and nuclei (arrow).
		GFP signal (right panel) appeared to be concentrated in the appressorium at the position of the nucleus.
		A mitogen-activated protein kinase of the corn leaf pathogen Cochliobolus heterostrophus is involved in conidiation, appressorium formation, and pathogenicity: diverse roles for mitogen-activated protein kinase homologs in foliar pathogens.
	ec.asm.org /cgi/content/full/3/6/1525 (4826 words)

	RedOrbit - Science - Gene Expression Profiles of Blumeria Graminis Indicate Dynamic Changes to Primary Metabolism ... (Site not responding. Last check: 2007-10-14)
		At 15 hpi, a penetration peg forms underneath the appressorium and breaks the plant cell wall by the combined action of high turgor pressure in the appressorium and enzymatic cell wall breakdown at the tip of the peg itself (Francis et al., 1996; Pryce-Jones et al., 1999).
		The postpenetration stages are those that follow the formation of a fully functional haustorium (24 hpi) and result in the development of hyphae on the surface of the leaf (epiphytic mycelia) that eventually produce abundant conidia 3 to 4 dpi.
		Once the haustoria are in place, the nutrients derived from the plant are channeled through glycolysis to support protein and DNA synthesis for the proliferation of the external hyphae and formation of masses of conidia in which glycogen is laid down as storage.
	www.redorbit.com /news/display?id=192343&source=r_scienc (7957 words)

	Magnaporthe grisea Pth11p Is a Novel Plasma Membrane Protein That Mediates Appressorium Differentiation in Response to ...
		Magnaporthe grisea Pth11p Is a Novel Plasma Membrane Protein That Mediates Appressorium Differentiation in Response to Inductive Substrate Cues -- DeZwaan et al.
		Gilbert, R., Johnson, A., and Dean, R. (1996) Chemical signals responsible for appressorium formation in the rice blast fungus Magnaporthe grisea.
		Mitchell, T., and Dean, R. (1995) The cAMP-dependent protein kinase catalytic subunit is required for appressorium formation and pathogenesis by the rice blast pathogen Magnaporthe grisea.
	www.plantcell.org /cgi/content/full/11/10/2013 (8157 words)

	Stanford Graduate School of Plant Biology - Image Gallery Page
		The projection of z-series confocal images showed both aerial fungal structures [i.e., conidium (C) and appressorium (A)] and the structure inside the plant cell, haustorium (H).
		Arabidopsis epidermal cell (Ep) periphery is shown as green by the plasma membrane-GFP tagged protein, Q8 (arrows) and the propidium iodide stained fungal structures, including conidium, appressorium, and haustorium are shown as red.
		A haustorium is a fungal feeding structure formed in the plant epidermal cell within 24 hours by penetration of an appressorium.
	carnegiedpb.stanford.edu /~webguru/plantbio/imagecollection.html (626 words)

	Early Expression of the Calmodulin Gene, Which Precedes Appressorium Formation in Magnaporthe grisea, Is Inhibited by ...
		Attachment to the surface is necessary for the early expression of the calmodulin gene and appressorium formation.
		Hard-surface contact is known to be required for appressorium formation (8).
		on the correlation of ConA inhibition of attachment and appressorium
	jb.asm.org /cgi/content/full/181/11/3571 (5134 words)

	PPA660: Lecture 6 - Penetration
		Thines, E., Weber, S. and J., T. MAP Kinase and protein kinase A-dependent mobilization of triacylglycerol and glycerol during appressorium turgor generation by Magnaporthe grisea.
		Mitchell, T. and Dean, R. The cAMP-dependent protein kinase catalytic subunit is required for appressorium formation and pathogenesis by the rice blast fungus Magnaporthe grisea.
		Xu, J. and Hamer, J. MAP kinase and cAMP signaling regulate infection structure formation and pathogenic growth in the rice blast fungus Magnaporthe grisea.
	www.ca.uky.edu /agcollege/plantpathology/farman/ppa66L6.htm (889 words)

	Biotechnology University of Kaiserslautern
		Using these triggers and their signalling chains, several inhibitors of appressorium formation from natural sources have been identified in our lab.
		Sterner, O., E.Thines, F. Eilbert and H. Anke: Glisoprenins C, D and E, new inhibitors of appressorium formation in Magnaporthe grisea, from cultures of Gliocladium roseum.
		Eilbert, F., E. Thines and H. Anke: Effects of antifungal compounds on conidial germination and on the induction of appressorium formation in Magnaporthe grisea.
	www.uni-kl.de /biotech/home_magnp.htm (630 words)

	Springer WienNewYork -
		Germlings grown on substrata inductive for appressorium formation in the presence of buffered synthetic peptides containing the amino acid sequence RGD, e.g., RGD, RGDS, GRGD, and GRGDGSPK (0.5¿2.0 mM), were inhibited from developing appressoria.
		Furthermore, 0.5 mm diameter micropipettes that are normally inductive for appressorium formation when positioned between the germling apex and the substratum did not induce appressorium formation when coated with the RGD peptide.
		Those observations lead to the hypothesis that an integrin-like protein may be involved in the process of signaling for initiation of appressorium formation in Uromyces.
	www.springer.at /periodicals/article_issue.jsp?articleID=xxxxxxxxx251xxxxxxxx0109&volumeIssueID=null&periodicalID=null&supplement=null (324 words)

	Mycorrhiza Literature Exchange
		Arbuscular mycorrhizal symbiosis is induced upon a series of recognition events involving the reorganization of both plant and fungal cellular programs culminating in the formation of appressoria on the epidermal root cells.
		We established an in vitro system of Glomus mosseae and Petroselinum crispum for studying appressorium formation and found that after 120 h first appressoria developed in the root epidermis.
		The up-regulation of these genes opens the possibility that Ca2+ plays a role in the early stages of mycorrhiza formation as it has been found in other plant-microbe interactions such as the Rhizobium symbiosis or the Magnaporthe grisea/rice pathogenic interaction.
	mycorrhiza.ag.utk.edu /latest/latest04/04_7breun1.htm (274 words)

	Department of Plant Pathology and Microbiology
		Another remarkable form of development at the level of a single cell is the formation of the appressorium of the rice blast fungus, Magnaporthe grisea.
		The appressorium is an infection structure that is required for physical penetration of the plant host.
		In our examination of appressorium formation we discovered peptides that inhibit appressorium formation.
	plantpathology.tamu.edu /people/bios/ebbole.html (456 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		As many of those genes involved in appressorium formation as possible will be identified through differential hybridization analysis.
		Gene expression in various appressorium deficient mutants will be exploited to identify potentially key genes.
		Finally, to begin to define the interplay of proteins regulating appressorium formation the interaction of gene products will be evaluated.
	www.cs.utexas.edu /users/yguan/NSFAbstracts/Abstracts/BIO/IBN.BIO.a9874430.txt (184 words)

	ARS \| Publication request: Rust Fungi: An Obligate-Parasitic Life Style
		Infection begins with the germination of a spore on the leaf surface, followed by the development of an appressorium.
		The development of the appressorium depends on a thigmotrophic signal triggered by the specific topography of the host plant surface.
		An infection peg formed by the appressorium enters the leaf through a stoma, followed by the development of a substomatal vesicle, infection hypha, haustorial mother cell, penetration of a photosynthetic mesophyll cell, and the establishment of a haustorium.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=138564&pf=1 (190 words)

	magnaporthe_grisea (Site not responding. Last check: 2007-10-14)
		When these spores land on leaves and other aerial tissues of susceptible plants they germinate, developing the appressorium.
		The appressorium penetrates the plant cell by producing a penetration peg.
		Pressure in the appressorium increases and the structure explodes, forcing the penetration peg through the cell wall and into the cell.
	www.900freedietplans.com /wiki/?title=Magnaporthe_grisea (901 words)

	Fungal Melanin
		To identify genes that express preferentially during germination and appressorium formation, we constructed cDNA library and performed differential cDNA screening.
		During appressorium differentiation, de novo transcripts of the three melanin biosynthesis genes accumulated by 1-2 h after the start of conidial incubation at 24 C and began to decrease at 6 h.
		At present, we are investigating expression patterns of these enzymes during appressorium differentiation.
	www.fgsc.net /asilomar/melanin.html (1330 words)

	From pathogenicity genes to pathogen genomes: PTH11 and all the rest (Site not responding. Last check: 2007-10-14)
		Consistent with this, exogenous activation of appressorium signaling suppressed the pth11 mutant defects.
		These experiments indicated that Pth11p can activate appressorium differentiation in response to inductive surface cues, repress differentiation on poorly inductive surfaces, and that multiple signaling pathways mediate differentiation.
		DeZwaan, T. M., Carroll, A. M., Valent, B., and Sweigard, J.A. Magnaporthe grisea Pth11p is a novel plasma membrane protein that mediates appressorium differentiation in response to inductive substrate cues.
	ag.arizona.edu /pls/seminars/SweigardABS.htm (301 words)

	The BSPP - BSPP Presidential Meeting 2003
		grisea forms a specialised infection structure called an appressorium which is used to penetrate the tough outer cuticle of rice leaves, allowing the fungus entry to the underlying tissues (Talbot, 2003).
		We have investigated glycogen, trehalose, and lipid metabolism, fatty acid beta-oxidation and the glyoxylate cycle and have evidence that each of these processes contributes to virulence, albeit at different stages of pathogenesis-related development.
		Talbot, N.J. (2003) On the trail of a cereal killer: investigating the biology of Magnaporthe grisea.
	www.bspp.org.uk /archives/bspp2003/bspp03session3.htm (1875 words)

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