|Drenth, A - UNIVERSITY OF QUEENSLAND|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: March 12, 1999
Publication Date: N/A
Technical Abstract: Plant pathogens of the class Oomycetes have affected man's welfare to a great extent in most parts of the world. The Oomycetes include a number of important plant pathogens such as the Pythiums, Phytophthoras, and the Peronosporaceae, commonly known as the downey mildews. The mostly soil-borne Pythium and Phytophthora cause severe yield losses in many crops sthroughout the world. The Irish potato famine caused by Phytophthora infestans led to large-scale starvation and migration from Ireland in the middle of the 19th century. At that time man found it hard to believe that something so small could cause so much damage. Although one fungal spore seems insignificant, a large population of such small spores can form a formidable enemy which immediately highlights the importance of understanding fungi at the population level. Species belonging to the downey mildews cause problems in many important crops which are currently used as food. A downey mildew of historical significance is downy mildew on grapes, caused by Plasmopara viticola. This Oomycete devastated European vineyards during the 1870's and 1880's until observations by Millardet led to the introduction of the first fungicide, Bordeaux mixture, to control fungal pathogens. The purpose of this review is to summarize the current state of knowledge about the population biology of fungi in the class Oomycetes. Since suitable genetic markers are now widely and cheaply available and solidly embedded in population genetic theory many previously inaccessible questions now can be addressed. Although this field is still in its infancy, we expect a significant increase in our understanding of the population genetics of the Oomycetes during the next few years.