Ashbya gossypii

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Ashbya gossypii
Scientific classification
Kingdom: Fungi Phylum: Ascomycota Subphylum: Saccharomycotina Class: Saccharomycetes Order: Saccharomycetales Family: Saccharomycetaceae Genus: Eremothecium Species: A. gossypii Subspecies: ATCC 10895, FDAG
Binomial name
Ashbya gossypii S. F.Ashby & W. Nowell, 1926
Synonyms
Eremothecium gossypii Nematospora gossypii

[edit] History and Significance

Ashbya gossypii is a filamentous fungus or mold which was originally isolated from cotton as the pathogen of stigmatomycosis by Ashby and Novell in 1926. This disease affects the development of hair cells in cotton bolls and can be transmitted to citrus fruits, which thereupon dry out and collapse (dry rot disease). In the first part of the 20^th century, A. gossypii and a few related fungi made it virtually impossible to grow cotton in certain regions of the subtropics, causing severe economical losses. Control of the spore transmitting insects - cotton stainer (Dysdercus suturellus) and Antestia - permitted to fully eradicate infections. It was recognized that A. gossypii is a natural overproducer of riboflavin, also known as vitamin B₂. This made it an interesting organism for industries, where genetically modified strains are still used to produce this vitamin.

[edit] A. gossypii as a model organism

A few years ago, A. gossypii became recognized as an attractive model to study the growth of long and multinucleated fungal cells ( hyphae) because of its small genome, haploid nuclei, and efficient gene targeting methods. It is generally assumed that a better understanding of filamentous fungal growth will greatly stimulate the development of novel fungicides. The use of Ashbya gossypii as a model organism is particularly promising because of the high level of gene order conservation (synteny) between the genomes of A. gossypii and the yeast Saccharomyces cerevisiae.

[edit] Genome

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[edit] Growth, Development and Morphology

Development from a spore to a mature mycelium in A. gossypii. (kindly provided by Dr. Philipp Knechtle)
a) Ungerminated spore
b) Isotropic growth phase in the germ bubble
c) Unipolar germling
d) Emergence of a second germ tube
e) Emergence of lateral branches and septum generation
f) Apical branching in mature hypha

The A. gossypii life cycle starts with the only known phase of isotropic growth in wild type: germination of the haploid spore to form a germ bubble. This is followed by apical growth, extending two germ tubes in succession on opposing sites of the germ bubble. More axes of polarity are established with lateral branch formation in young mycelium. Maturation is characterized by apical branching (tip splitting) and a dramatic increase of growth speed (up to 200 μm/h at 30°C), which enables it to cover an 8 cm Petri dish of full medium in about 7 days. Sporulation is thought to be induced by nutrient deprivation, leading to contraction at the septa, cytokinesis and subsequent abscission of sporangia which contain up to 8 haploid spores. Hyphae are compartmentalized by septa, which in young parts appear as rings that allow transfer of nuclei and in older parts may appear as closed discs. Compartments typically contain around eight nuclei.

[edit] Research Interests

Please help improve this article by expanding this section. Further information might be found on the talk page or at requests for expansion. Please remove this message once the section has been expanded. This article has been tagged since March 2007.

[edit] References

• Ashby SF and Nowell W (1926). "The Fungi of Stigmatomycosis.". Ann Bot os-40 (1): 69-84. 
• Dietrich FS, Voegeli S, Brachat S, Lerch A, Gates K, Steiner S, Mohr C, Pohlmann R, Luedi P, Choi S, Wing RA, Flavier A, Gaffney TD and Philippsen P (2004). "The Ashbya gossypii genome as a tool for mapping the ancient Saccharomyces cerevisiae genome.". Science 304 (5668): 304-7. PMID 15001715. 
• Philippsen P, Kaufmann A and Schmitz HP (2005). "Homologues of yeast polarity genes control the development of multinucleated hyphae in Ashbya gossypii.". Curr Opin Microbiol 8 (4): 370-7. PMID 16023404. 
• Gladfelter AS (2006). "Nuclear anarchy: asynchronous mitosis in multinucleated fungal hyphae.". Curr Opin Microbiol 9 (6): 547-52. PMID 17045513. 

[edit] External links

• The Ashbya Genome Database.
• Peter Philippsen’s lab at the Biozentrum in Basel, Switzerland.
• Hans-Peter Schmitz’ lab at Universität Osnabrück, Germany.
• Amy Galdfelter’s lab at Dartmouth College, USA.
• Jürgen Wendland’s lab at the HKI in Jena, Germany.
• Fred Dietrich’s lab at Duke University, USA.