The spores of Phytophthora : weapons of the plant destroyer

Key Points Although many researchers would consider oomycetes as fungi, officially oomycetes such as the genus Phytophthora are classified taxonomically in the Straminipilia kingdom, with diatoms and brown algae their nearest taxonomic neighbours. The phytopathogenic Phytophthora are economically significant pathogens, with Phytophthora infestans , the causative agent of potato blight, responsible for an estimated US$5 billion of damage each year. New techniques for genetic, genomic and proteomic analyses were initially applied to more tractable mycological systems such as the basidiomycetes and ascomycetes. However, in the past decade great advances have been made in developing these analytical tools for oomycetes, with Phytophthora leading the way. In this article, the authors provide an overview of the results obtained in molecular studies on Phytophthora spores from the past 4 or 5 years. Several spore-specific genes have now been identified. Further analysis of the different stages of the Phytophthora life cycle might eventually lead to the development of effective strategies for controlling Phytophthora disease. Members of the genus Phytophthora are among the most serious threats to agriculture and food production, causing devastating diseases in hundreds of plant hosts. These fungus-like eukaryotes, which are taxonomically classified as oomycetes, generate asexual and sexual spores with characteristics that greatly contribute to their pathogenic success. The spores include survival and dispersal structures, and potent infectious propagules capable of actively locating hosts. Genetic tools and genomic resources developed over the past decade are now allowing detailed analysis of these important stages in the Phytophthora life cycle.