Phytophthora has been rebuilt to fix security-related problems and to restore GIS tools. These tools allow users to visualize the geospatial, temporal, and environmental contexts of Phytophthora discoveries. The next phase is to update species information and add data derived from large-scale surveys. If you have suggestions and requests to make the database better, please contact Seogchan Kang (sxk55@psu.edu).
Genus wide phylogeny for Phytophthora using four mitochondrial loci (cox2, nad9, rps10 and secY; 2,373 nucleotides). Maximum likelihood branch lengths shown. Numbers on nodes represent bootstrap support values for maximum likelihood (top), maximum parsimony (middle) and Bayesian posterior probabilities as percentages (bottom). Nodes receiving significant support (>95%) in all analysis are marked with an asterisk (*). Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).
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Phytophthora richardiae Buisman 1927 (Oomycetes, Pythiales)
Phytophthora cryptogea var. richardiae (Buisman) S.F. Ashby 1929
Distribution: Asia, Australasia, Australia, Europe, North America (USA).
Substrate: Roots.
Disease Note: Root rot.
Host: Zantedeschia spp. (Araceae). Also Robinia (Fabaceae), Asparagus (Asparagaceae), Daucus carota (carrot, Apiaceae), and Lycopersicon esculentum (tomato, Solanaceae) (Erwin & Ribeiro 1996).
Supporting Literature:
Erwin, D.C., and Ribeiro, O.K. 1996. Phytophthora Diseases Worldwide. APS Press, St. Paul, Minnesota, 562 pages.
Kroon, L.P.N.M., Bakker, F.T., van den Bosch, G.B.M., Bonants, P.J.M., and Flier, W.G. 2004. Phylogenetic analysis of Phytophthora species based on mitochondrial and nuclear DNS sequences. Fungal Genet. Biol. 41: 766-782
Tucker, C.M. 1931. Taxonomy of the genus Phytophthora de Bary. Univ. Missouri Agric. Exp. Sta. Bull. 153: 1-208
Updated on Jun 06, 2006
P. richardiae is classified in group VI (Stamps et al. 1990). G. Hall (1991d) gives descriptions of the disease and the pathogen. See Tables 4.2 and 4.3 in Phytophthora Diseases Worldwide (Erwin and Ribeiro 1996) for tabular keys. Morphology is shown in Figure 1.
1. Sporangia
Sporangia are nonpapillate, variable in shape, ovoid, obpyriform, obturbinate, often with more than one apex, and occasionally have a lateral attachment. They are persistent on the stalk and proliferate internally. Sizes vary from 40 to 60 µm long x 20 to 40 µm wide, average 52 x 33 µm (Buisman 1927) or 41.7 x 26.2 µm (Ashby 1929b). Sporangiophores are unbranched.
2. Hyphal Swellings
Hyphal swellings are large, spherical, rounded, or angular, often with radiating hyphae, and in chains (catanulate).
3. Chlamydospores
Chlamydospores are not produced.
4. Sex Organs
P. richardiae is homothallic. Antheridia are large, often >20 µm wide, and most often amphigynous with characteristic protuberances but occasionally paragynous. Oogonia measure 34 to 38 µm in diameter, average 32 µm (Buisman 1927); 29 to 48 µm, average 39 µm (Ashby 1929b); average 28.9 µm (Tucker 1931). Oospores form readily in host tissue and average 29.0 µm in diameter (Buisman 1927); 19 to 41 µm, average 30.7 µm (Ashby 1929b); average 25.4 µm (Tucker 1931). Oospore walls are very thick (about 5 µm) (G. Hall 1991d).
5. Growth Temperatures
The minimum temperature for growth is 10oC, optimum 24 to 25oC, and maximum 30 to 32oC. Tucker (1931) reports minimal growth at 30oC, optimal at 20oC, and no growth at 30oC. He notes that P. richardiae resembles P. cryptogea, which grows at 10oC, optimally at 25oC, and has some growth at 30oC.
6. Distinguishing Characteristics
P. richardiae is morphologically similar to P. vignae and P. erythroseptica and is separated mainly by the size, shape, and orientation of the antheridia (G. Hall 1991d).
Nomenclature information was provided by the the Systematic Botany and Mycology Laboratory in USDA-ARS.
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