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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 chrysanthemi Naher, Hi. Watan., Chikuo & Kageyama 2011 (Oomycetes, Pythiales)
Distribution: Japan.
Disease Note: Stem and root rot.
Host: Chysanthemum (Asteraceae).
Supporting Literature:
Naher, M., Motohash, K., Watanabe, H., Chikuo, Y., Senda, M., Suga, H., Brasier, C., and Kageyama, K. 2011. Phytophthora chrysanthemi sp. nov., a new species causing root rot of chrysanthemum in Japan. Mycol. Progr. 10: 21-31.
Updated on Jul 22, 2011
Phytophthora chrysanthemi Naher M, Watanabe, H., Chikuo, Y., & Kageyama K. was isolated from stem and root rot of chrysanthemum in the Gifu and Toyama prefectures of Japan. It is placed in clade 10 closely related to P. parsiana.
1. Sporangia
Sporangium is formed rarely on solid agar, but profuse in water culture when mycelial plug from V8A medium is incubated for 24 h. Sporangium is mainly terminal, and sympodial sporangiophore is occasionally formed in water culture(Fig1). Sporangium is noncaducous, nonpapillate, usually ellipsoid, ovoid or pyriform. Average length and width of sporangia is 42.2 ± 8 X 27.9 ± 6:1 µm (overall range 24– 59×16–43 μm), and the length/width ratio is 1.4. Sporangium proliferates extended and nested or internally with 3–8 sporangia. Zoospores are discharged through an exit pore 6–14 μm wide.
2. Chlamydospores
Spherical chlamydospore is terminal, lateral or intercalary, and sometimes abundant on mycelium, formed within 10–15 days in V8A medium or water culture. The thin-walled (1–2 μm) chlamydospore measures 27–46 μm (average 39.3±4.9 μm) in diameter(Fig1).
3. Sex Organs
The isolate is homothallic; oogonia are abundantly produced even in a single-zoospore isolate on V8A medium after 10 days. Oogonium is terminal, often laterally sessile and intercalary with smooth walls; mostly spherical or nearly spherical, and occasionally possessing a distinct funnel-shaped stalk; oogonium is 26–46 μm in diameter (average 38.6 ± 3.4 μm) and acquires a golden brown color with aging(Fig2). Oospore is aplerotic, spherical and average 29.4 ± 3.98 μm in diameter, ranging from 19 to 35 μm. The thick oospore wall is about 2–5 μm (average 3.4 ± 0.6 μm), often turning golden brown with age. Antheridium is mostly terminal and occasionally intercalary; predominantly paragynous but sometimes amphigynous. It is barrel-or club-shaped to irregular, and dimensions range from 12–24×7–19 μm (average 19 ± 5.9 X 12.1 ± 3.9 µm).
4. Growth Temperatures
Colony grows moderately slow in V8A medium. Radial growth averages 4.1 mm per day at the optimum temperature of 30°C on V8A. The maximum temperature is 35°C and no growth occurs at 5°C(Fig3).
5. Growth Characteristics in Culture
Colony is radiate with cottony aerial mycelia on PDA at 20°C in darkness. On V8A, colony is submerged, radiate and exhibit slightly mosaic patterns. Hypha is sympodially branched and main hypha is up to 7.3 μm in diameter. Mostly lateral, intercalary hyphal swelling is abundantly produced both in agar medium and in water culture. Hyphal swellings are elongated, irregular to globose, and usually large (up to 67 μm).
6. Distinguishing Characteristics
The species is characterized by the formation of hyphal swellings and chlamydospores, internal proliferation with 8–9 sporangia, distinctive intercalary antheridia, and funnel-shaped oogonia(Fig2). It is a high temperature species as
the isolates can grow even at 35°C.
Causes root and stem rot of chrysanthemum (Fig4).
Naher, M., Motohash, K., Watanabe, H., Chikuo, Y., Senda, M., Suga, H., Brasier, C., Kageyama, K.2011. Phytophthora chrysanthemi sp. nov., a new species causing root rot of chrysanthemum in Japan. Mycol Progress 10:21–31
This species page was adapted from Naher et al. (2011). The contribution of images by Dr. Koji Kageyama are gratefully acknowledged.
Isolate list