Welcome to the Phytophthora database

Phytophthora is one of the more well known genera of plant pathogens under the general public. This is mostly due to its type species Phytophthora infestans, the cause of potato late blight, which has been the subject of both history and biology classes as it was the cause of the Irish potato famine in the 19th century. The economic and ecological significance of the genus however extends far beyond the impact of its type species . International plant trade has spread many Phytophthora species beyond their natural area of origin.

Some of these invasive species, like Phytophthora ramorum in Europe and North America, and Phytophthora cinnamomi in Australia, are known to cause great damage to the ecosystems they invade.  Many of the more than 90 members of the genus are treated as quarantine organisms. Proper identification of Phytophthora species is essential to distinguish low risk species from quarantine pathogens, and for providing a proper risk assessment and control strategy.
Phytophthora and other oomycetes are part of the kingdom stramenopila (Baldauf et al. 2000, Kamoun et al (2003) and are more closely related to brown  algae then to fungi. Young Phytophthora mycelium is aseptate.  Phytophthora spp. produce biflagellate motile zoospores in sporangia. In addition, some species can form chlamydospores to survive adverse conditions. Phytophthora species can be homothallic or heterothallic and the sexual oospores form after fertilization of an oogonium by an antheridium.


Phytophthora species can be distinguished from the closely related oomycete  genus Pythium by differences in the release of zoospores from the sporangium. In Phytophthora the zoospores form within the sporangium, while in Pythium the cytoplasm first exits the sporangium through a discharge tube into a vesicle, zoospores then form inside this vesicle.

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