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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 mexicana Hotson & Hartge 1923 (Oomycetes, Pythiales)
Notes: According to Mchau & Coffey (1995), only one isolate is available for examination. Mchau & Coffey (1995) listed Phytophthora mexicana as a possible synonym of Phytophthora tropicalis (as Phytophthora capsici type CapA).
Distribution: North America (Mexico, type). Possibly introduced from the Netherlands (Erwin & Ribeiro 1996).
Substrate: Fruit.
Disease Note: Fruit rot. Also black wilt and damping off.
Host: Lycopersicon esculentum (Solanaceae).
Supporting Literature:
Erwin, D.C., and Ribeiro, O.K. 1996. Phytophthora Diseases Worldwide. APS Press, St. Paul, Minnesota, 562 pages.
Mchau, G.R.A., and Coffey, M.D. 1995. Evidence for the existence of two subpopulations in Phytophthora capsici and a redescription of the species. Mycol. Res. 99: 89-102
Updated on Jun 16, 2006
P. mexicana is classified in group II (Stamps et al. 1990). 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 ovoid to fusiform, often with distorted shapes; occasionally there are two papillae on the same sporangium; lateral attachment of sporangium is possible; they are sometimes intercalary; sporangia are persistent on the hyphae and 46 to 77 x 16 to 33 µm (average 45.2 x 23.1 µm). Sporangia are usually formed on unbranched sporangiophores; however, formation of sporangia on simple sympodia is illustrated by Hotson and Hartge (1923).
2. Hyphal Swellings
Hyphal swellings are not produced.
3. Chlamydospores
Chlamydospores are rare; spherical, 28 to 44 µm in diameter, and mostly intercalary.
4. Sex Organs
P. mexicana was described as homothallic in the original description (Hotson and Hartge 1923) but later as heterothallic by Savage et al. (1968). Antheridia are amphigynous; oogonia are 30 to 37.5 µm in diameter (average 30.7 µm) and produced in abundance at temperatures between 8 and 10oC; oospores are 24 to 37.4 µm (average 25.4 µm).
5. Growth Temperatures
The minimum temperature for growth is 10oC, the optimum 27.5oC, and the maximum <35oC.
6. Distinguishing Characteristics
P. mexicana closely resembles P. parasitica but differs from it, according to Hotson and Hartge (1923), by its larger oospores and host specificity. Leonian and Geer (1929) proposed to combine P. mexicana with P. erythroseptica, a species that it resembles in many aspects. On the other hand, Tucker (1931) found that this species closely resembled P. parasitica.
Nomenclature information was provided by the the Systematic Botany and Mycology Laboratory in USDA-ARS.
Isolate list