Difference between revisions of "Ustilago"
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==Cell structure and metabolism==
==Cell structure and metabolism==
Revision as of 18:05, 10 November 2006
A Microbial Biorealm page on the genus Ustilago
Higher order taxa
Eukaryota; Fungi; Basidiomycota; Ustilaginomycetes; Ustilaginomycetidae; Ustilaginales; Ustilaginaceae; Ustilago
Ustilago maydis (zeae is obsolete name), U. scitaminea (cane smut), U. lituana (grass smut), U. violacea, U. scabiosae, U. utriculosae, U. sphaerogena, U. bullata, U. nigra, U. hordei, U. heterogena
Description and significance
The basidomyctete fungus, Ustilago maydis, is a type of yeast that most commonly inhabits soil or plant environments particularly that are dead. However, it is known as a dimorphic fungus since it can grow in two manners; one is the single-celled form on dead plants and the other is a filamentous mycelial form during the invasion of a plant and also during mating. Nonetheless it is viewed as a pathogen of seeds and flowers of cereals, wheat, corn, and grasses. Typically it can most often be found affecting sweet corn (CWBInfo, 1999-2001). The most prominent feature of its infection on corn is its tumor-like structures that form on the aerial parts of the plant. Plants having these features are characterized as having smut disease.
Ustilago maydis is used often for its homeopathic remedies for the female genitalia. Common uses are for irritation of the ovaries, dark periods, non-menstrual bleeding (passive, non-passive, string bleeding), and pain in the ovaries or the womb, which includes cramping (ABC 2001-04). Some strains of the fungal pathogen emit killer toxins, such as KP6, which are further encoded by double-stranded RNA viruses in its cell cytoplasm (Li, 1999). It also is an excellent model used in analyzing phytopathogenesis in the molecular laboratory.
Even though it is a fungus, it doesn’t have all negative effects. Corn smut is a delicacy in Mexico. This dish is called huitlacoche, which is created before the teliospores are ripe and the inside is moist with the gall being white to gray on the outside. Farmers appreciate this fungus because they can receive a high price relative to unaffected corn crop. Some farmers will introduce this fungus to their crops on purpose (Volk, 1998).
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?
Cell structure and metabolism
The composition of the cell wall is not completely deciphered. Recent studies indicate that the walls are made of mostly of polysaccharides and chitin. Chitin and phosphate are more abundant in the mycelial form that in the yeast (Ruiz-Herrara, 1998). Knowledge of the cell wall composition and metabolism of Ustilago maydis is still being investigated. However, recent studies have shown that cell walls of the yeast and mycelial forms are mostly made up of polysaccharides. Mycelial forms contain both polysaccharides and chitin (Feldbrugge, 2004).
Ustilago maydis is useful in studying many things, such as mating determination, homologous recombination and signaling pathways. This is because during the life cycle of U. maydis, non-pathogenic haploid cells, which grow like yeast, fuse together to form a dikaryotic hyphae (Bolker, ). U. maydis can only induce disease in the dikaryotic stage that occurs after mating. This process involves cAMP and mitogen-activated protein kinase (MAPK) signaling that regulate transcriptional and other morphological responses. One of the products made from the dikaryotic stage is a major regulator needed for pathogenic development. The major regulator then orchestrates a complex transcriptional cascade which has been uncovered by genomic strategies (Smith, 2003).
Signal transduction pathways are important for many of features of fungal metabolism. For example, many human fungal pathogens show some type of dimorphism, and a common element in these and other fungi is MAPK. Each pathway is made of a signal cascade involving the phosphorylation of three protein kinases. These kinases include a MAPK kinase kinase (MAPKKK), a MAPK kinase (MAPKK), and the MAPK. This protein, in turn, phosphorylates one or more target transcription factors and other substrates (Smith, 2003). U. maydis is a pathogen of maize, for which cell fusion and pathogen development are controlled by two separate mating loci: a and b. The a locus encodes the pheromone and a seven-transmembrane protein pheromone receptor which constitute the cell recognition system. The b loci is required for control of pathogenic development. The pheromone-responsive MAPK pathway is involved in the activation of both the a and b loci (Smith, 2003).
Habitat; symbiosis; contributions to the environment.
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Enter summarries of the most rescent research here--at least three required
ABC Homeopathy. (2001-04). Ustilago maydis. Influenca ltd. Retrieved November 3, 2006 from []
Bölker, Michael. Ustilago maydis – a valuable model system for the study of fungal dimorphism and virulence. Universität Marburg, Fachbereich Biologie, Karl-von-Frisch-Strasse 8, D-35032 Marburg, Germany.
CBWInfo.com. (1999-2001). Factsheets on Chemical Biological and Warfare Agents. Retrieved November 3, 2006 from []
Feldbrugge, M. Kamper J, , Steinberg G, Kahmann R. (2004). Regulation of mating and pathogenic development in Ustilago maydis. Dec;7(6):666-72 Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, D-35043 Marburg, Germany.
“Host-Parasite Interactions.” Fungal Genetics Conference. March 2001. Access 10 November 2006 []
Kamper, J. (2006). Insights from the genome of the biotrophic fungal plant pathogen Ustilago maydis. Nature. November 2, 2002. Pages 97-101.
Li, N. (1999). Structure of Ustilago maydis killer toxin KP6 alpha-subunit. A multimeric assembly with a central core. The Journal of Biological Chemistry Vol 274(29). Pages 20425-31.
Madera, M., Vogel, C., Kummerfeld, S.K., Chothia, C. and Gough, J. (2004) "The SUPERFAMILY database in 2004: additions and improvements." Nucl. Acids Res., 32, D235-D239.
Ruiz-Herrara, J. (1998). “The fungus Ustilago maydis from the Aztec cuisine to the research laboratory.” Internatl Microbiol. Mexico: Springer-Verlag Iberica.
Smith, David G. Maria D. Garcia-Pedrajas, Wei Hong, Zhanyang Yu, Scott E. Gold, and Michael H. Perlin. An ste20 Homologue in Ustilago maydis Plays a Role in Mating and Pathogenicity. Department of Biology, University of Louisville, Louisville, Kentucky, Department of Plant Pathology, University of Georgia, Athens, Georgia. Received 13 May 2003/ Accepted 3 December 2003
Volk, T.J. (1998). Smuts on the Internet. []
“UC Pest Management Guidelines” University of UC Davis. January 2006. Accessed 10 November 2006. []
Edited by student of Dr. Kirk Bartholomew