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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 macrochlamydospora J.A.G. Irwin 1991 (Oomycetes, Pythiales)
Distribution: Australia.
Substrate: Stems, roots.
Disease Note: Stem and root rot.
Host: Glycine max (soybean, Fabaceae).
Supporting Literature:
Erwin, D.C., and Ribeiro, O.K. 1996. Phytophthora Diseases Worldwide. APS Press, St. Paul, Minnesota, 562 pages.
Updated on Jun 15, 2006
P. macrochlamydospora would be classified in group III or IV (Stamps et al. 1990) because of its production of semipapillate sporangia; however, the absence of a sexual stage indicates that this is an arbitrary placement. Morphology is shown in Figure 1. See Tables 4.2 and 4.3 in Phytophthora Diseases Worldwide (Erwin and Ribeiro 1996) for tabular keys.
1. Sporangia
Sporangia are formed terminally on long (up to 500 µm) sporangiophores that proliferate either internally or sympodially. Sporangia are semipapillate, ellipsoid to obpyriform, and measure 20 to 50 x 18 to 36 µm (Figure 1.2 and Figure 1.3). Zoospores that measure 9 to 13 x 8 to 10 µm are released from the sporangium.
2. Chlamydospores
Large, spherical chlamydospores that form on solid or liquid V8 juice media are terminal or intercalary (Figure 1.5), 24 to 84 µm in diameter (average 55 µm ) with walls 2.5 to 4.0 µm thick (Figure 1.6). The large size of the chlamydospore is the most distinctive feature.
3. Hyphal Swellings
Thin-walled hyphal swellings are spheroidal to ellipsoid (Figure 1.1) and are often formed in chains (Figure 1.4).
4. Growth Temperatures
The minimum temperature for growth is 6oC, optimum 23 to 30oC, and maximum 34oC.
5. Distinguishing Characteristics
P. macrochlamydospora differs from P. colocasiae, which produces semipapillate sporangia (group IV), by its production of much larger chlamydospores. P. colocasiae also produces oogonia and oospores, but P. macrochlamydospora does not.
Nomenclature information was provided by the the Systematic Botany and Mycology Laboratory in USDA-ARS.
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