Pythium oligandrum

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Classification

Kingdom: Chromalveolata

Phylum: Heterokontophyta

Class: Oomycetes

Order: Pythiales

Family: Pythiaceae

Species

NCBI: Pythium oligandrum [1]

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Description and Significance

Describe the appearance, habitat, etc. of the organism, and why you think it is important.

Genome Structure

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, Metabolism and Life Cycle

Interesting features of cell structure; how it gains energy; what important molecules it produces.

Pythium oligandrum has two distinctive life cycles. One of which is asexual and the other is sexual. In the asexual lifecycle, P. oligandrum exists as a zoospore. A zoospore is a flagellated cell containing genetic material. The zoospore of P. oligandrum is diploid and contains the full genome. In the case of P. oligandrum, the zoospore is an important life stage because of the zoospores ability to move through water via its flagella. When conditions are suitable, the zoospore undergoes mitotic divisions and matures. Pythium oligandrum exists in its sexual life stage about 20% of the time(1). This life cycle is characterized by thick walled oospores. Oospores are a result of the fertilization of oogonium by antheridium, which is the male sex organ of the organism. The maturation of the oospores leads to the production of mycelium and a mature organism capable or reproduction and completing the cycle. Oospores are characterized by their thick cell walls and are relatively large cells.

Pythium oligandrum is a eukaryotic organism. They were once thought to be a type of fungi, but they lack chitin and are currently categorized as a protist. Their oospores are spiny walled, which distinguished them from other species of Pythium. Their mature stage is multi-cellular and filamentous. P. oligandrum is found in the rizzoshephere. P. oligandrum is parastic and hetertrophic. Being a non-phtosynthetic eukaryote, I suspect that is uses, or can use oxygen as a T.E.A.

Ecology and Pathogenesis

Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Can cause damping-off. This can potentially kill seeds because the organism attacks the first roots formed during germination. Considered an “aggressive microparasite” that forms parasitc relationships with plants and other microorganisms. For the latter reason, it can actually be beneficial to plants because it can provide as a sort of defense from other plant pathogens esp. fungi. For this reason, P. oligandrum is a potential biocontrol agent. However, because it infects fungi it can ruin mushroom crops such as those crops of the common mushroom(2) (Agaricus bisporus)

References

1. "Review report for the active substance Pythium oligandrum M1." EUROPEAN COMMISSION HEALTH & CONSUMERS DIRECTORATE-GENERAL. Web. <http://ec.europa.eu/food/plant/protection/evaluation/existactive/M1.pdf>.

2. Godfrey et al. 2003. Identification of Pythium oligandrum using species-specific ITS rDNA PCR oligonucleotides. The British Mycological Society. 107(7):790-796. Science Direct. 21. April 2011.

Author

Page authored by _____, student of Prof. Jay Lennon at Michigan State University.

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