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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 gemini Man in ’t Veld, K. Rosendahl, Brouwer & de Cock was isolated from Zostera marina (seagrass) in The Netherlands. It is a clade 6 species closely related to P. inundata.
1. Sporangia
Widely spaced catenulate and clustered intercalary hyphal swellings occasionally occurred both in agar and water culture. Sporangia formed abundantly in sterile filtered pond water with shapes varying from obovoid, to ellipsoid, ovoid and obpyriform , often with a tapered base with dimensions average 52.89 X 30.59 µm, length-breadth ratio 1.6:1. Sporangia have a conspicuous basal plug and are non-papillate with a wide exit pore. Sporangia discharge their zoospores quickly after formation and in older cultures only empty sporangia remain. Internal proliferation was not observed. Secondary sporangia may form by sympodial branching of the hypha directly below the terminal, primary sporangium (Fig. 1). The septum that delineates the secondary sporangium from the mycelium frequently forms in the hyphae carrying the primary sporangium, before the sympodial branch point, resulting in a sporangium with intercalary base. This characteristic has not been reported for any other Phytophthora species, at least not to our knowledge. Sporangia are non-caducous. Sporangiophores are undifferentiated from vegetative hyphae.
2. Chlamydospores
Chlamydospores were not observed.
3. Sex Organs
Sexual structures were not produced in single culture (not homothallic) nor in mating tests using Phytophthora cambivora CBS356.78 (A1), Phytophthora cryptogea PD20032149 (A1) or P. cambivora CBS376.61 (A2) as tester strains nor when the different P. gemini isolates were grown together. In addition, the type strain of P. gemini CBS123381 was paired with Phytophthora capsici CBS111332 (A1) and P. capsici CBS128.23 (A2), but again no sexual structures were observed.
4. Growth Temperatures
Minimum temperature for growth lies beneath 3° C, optimum temperature for growth between 24° C and 27° C. Maximum temperature at which growth was observed was 33° C .
5. Growth Characteristics in Culture
Colony morphology in PDA chrysanthemum pattern, sometimes obscured by aerial mycelium.
6. Distinguishing Characteristics
Phytophthora gemini can be differentiated from the related P. inundata by the possession of catenulate hyphal swellings in P. gemini, its unique combination of terminal sporangia and secondary sporangia formed by external proliferation, by the lack of internal proliferation and its optimum and maximum growing temperature
Phytophthora gemini has been isolated from decaying leaves and seeds of Zostera marina in The Netherlands.
Man in ’t Veld, W. A., Rosendahl, K. C. H. M., Brouwer, H., de Cock, A. W. A. M.. 2011, Phytophthora gemini sp. nov., a new species isolated from the halophilic plant Zostera marina in the Netherlands. Fungal Biology 115:724-732.
This species page was adapted from Man in ’t Veld et al. (2011). The photos shown in Fig. 1 were provided by Willem Man in ’t Veld at the Netherlands Plant Protection Service (NPD).
Isolate list