Phytophthora

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Phytophthora
Phytophthora porri on leek (Allium porrum)
Phytophthora porri on leek (Allium porrum)
Scientific classification
Domain: Eukaryota
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Oomycetes
Order: Peronosporales
Family: Pythiaceae
Genus: Phytophthora
Species

Phytophthora arecae
Phytophthora botryosa
Phytophthora cactorum
Phytophthora cajani
Phytophthora cambivora
Phytophthora capsici
Phytophthora cinnamomi
Phytophthora citricola
Phytophthora citrophthora
Phytophthora clandestina
Phytophthora colocasiae
Phytophthora cryptogea
Phytophthora drechslera
Phytophthora erythroseptica
Phytophthora fragariae
Phytophthora gonapodyides
Phytophthora heveae
Phytophthora humicola
Phytophthora idaei
Phytophthora ilicis
Phytophthora infestans
Phytophthora inflata
Phytophthora iranica
Phytophthora katsurae
Phytophthora lateralis
Phytophthora medicaginis
Phytophthora megakarya
Phytophthora megasperma
Phytophthora melonis
Phytophthora mirabilis
Phytophthora multivesiculata
Phytophthora nicotianae
Phytophthora palmivora
Phytophthora phaseoli
Phytophthora porri
Phytophthora primulae
Phytophthora pseudotsugae
Phytophthora quercina
Phytophthora ramorum
Phytophthora sinensis
Phytophthora sojae
Phytophthora syringae
Phytophthora tentaculata
Phytophthora trifolii
Phytophthora vignae

Phytophthora (from Greek phytón, “plant” and phthorá, “destruction, destruction”; “the plant-destroyer”) is a genus of plant-damaging Protisten of the Oomycetes (water moulds). Heinrich Anton de Bary described it for the first time in 1875.

Pathogens

Phytophthoras are mostly pathogens of dicotyledons, and are relatively host specific parasites. Many species of Phytophthora are plant pathogens of considerable economic importance. Phytophthora infestans was the infective agent of the potato blight that caused the Great Irish Famine (1845-1849). Plant diseases caused by this genus are difficult to control chemically, thus resistant cultivars are grown as a management strategy. Research beginning in the 1990s has placed some of the responsibility for European forest die-back on the activity of imported Asian Phytophthoras[1].

Other important Phytophthora diseases are:

Fungi resemblance

Phytophthora is sometimes referred to as a fungal-like organism but it is classified under a different kingdom altogether: Stramenopila (previously named Chromista). This is a good example of convergent evolution: Phytophthora is morphologically very similar to true Fungi yet its evolutionary history is quite distinct. In contrast to Fungi, stramenopiles are more closely related to plants than animals. Whereas Fungal cell walls are made primarily of chitin, stramenopile cell walls are constructed mostly of cellulose. Ploidy levels are different between these two kingdoms as are biochemical pathways.

Biology

Phytophthoras reproduce both sexually and asexually. They may be A1 or A2 mating type. Sporangia, zoospores, and chlamydospores are asexual. Oospores are sexual.


The life cycle of Phytophthora


File:Phytophtora reproduction.png
Phytophthora forms: A: Sporangia. B: Zoo pore. C: Chlamydospore. D: Oospore.

Notes

  • Department of Environment and Conservation, Western Australia - Dieback [1]

References

  • Lucas, J.A. et al. (eds.) (1991) Phytophthora based on a symposium held at Trinity College, Dublin, Ireland September 1989. British Mycological Society, Cambridge University Press, Cambridge, UK, ISBN 0-521-40080-5 ;
  • Erwin, Donald C. and Ribeiro, Olaf K. (1966) Phytophthora Diseases Worldwide American Phytopathological Society Press, St. Paul, Minnesota, ISBN 0-89054-212-0
  • Erwin, Donald C. (1983) Phytophthora: its biology, taxonomy, ecology, and pathology American Phytopathological Society Press, St. Paul, Minnesota, ISBN 0-89054-050-0
  • "APHIS List of Regulated Hosts and Plants Associated with Phytophthora ramorum" U.S. Animal and Plant Health Inspection Services

External links

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