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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 alni subsp. uniformis Brasier & S.A. Kirk 2004 (Oomycetes, Pythiales)
Notes: Probably a recent hybrid between Phytophthora cambivora and a Phytophthora close to Phytophthora fragariae (Brasier et al. 2004). Brasier et al. (2004) discuss nomenclatural issues associated with hybrids. This subspecies was previously known as the Swedish varient of the hybrid alder Phytophthora (Brasier et al. 2004).
Distribution: Europe.
Substrate: Roots, collars.
Disease Note: Root and collar rot of riparian, nursery and shelterbelt alders.
Host: Alnus spp. (alder, Betulaceae).
Supporting Literature:
Brasier, C.M., Kirk, S.A., Delcan, J., Cooke, D.E.L., and Jung, T. 2004. Phytophthora alni sp. nov. and its variants: designation of emerging heteroploid hybrid pathogens spreading on Alnus trees. Mycol. Res. 108: 1172-1184.
Phytophthora alni subsp. uniformis Brasier & S. A. Kirk is a subspecies of the hybrid species P. alni that is responsible for declining stands of Alnus species in Europe. This subspecies was initially classified as the Swedish variant hybrid type, first identified from Sweden in 1996. While the parentage of these hybrids was thought to be species closely related to P. cambivora and P. fragariae, more recent analysis suggests that Phytophthora alni subsp. alni is derived from several hybridization events between Phytophthora alni subsp. uniformis and Phytophthora alni subsp. multiformis (Ioos et al. 2006, 2007). Phylogenetic analysis places P. alni subspecies in clade 7a with P. cambivora and P. fragariae.
1. Sporangia
Sporangia not seen on CA. Produced sparsely in pea broth or when plugs from margins of actively growing cultures on CA or oatmeal agar are partially submerged in Petri’s solution, fresh, unsterile pond water or unsterile soil leachate. Borne singly on long sporangiophores, ellipsoid, non-papillate, noncaducous, with a broad exit pore. Sporangial length: range of means 48–59.8 µm; overall range ca 35–70 µm. Sporangial width: range of means 31.3–42.8 µm; overall range ca. 27.5–50 µm. Sporangial length:width ratio, range of means 1.32–1.62. After zoospore release showing nested and extended internal proliferation.
2. Chlamydospores
No chlamydospores observed.
3. Sex Organs
Gametangia generally frequent. Some cultures are highly unstable and chimeric, with gametangia produced only beneath patches of aerial mycelium. Oogonia mostly smooth-walled, but some slightly wavy edged-verrucose. Occasionally, oogonia have large, distorted beak-like protuberances. Oogonial diameter : range of isolate means (two isolates) 39.8–49 µm; overall range 37.5–55 µm. A high percentage (>90%) of oogonia usually with normal looking oospores. Oospore diameter: range of isolate means 33.3–43.4 µm; overall range ca 30–47.5 µm. Antheridia consistently two-celled and amphigynous. The antheridial cross-wall is often close to the base of the antheridium and can be overlooked. Antheridial length: range of isolate means 19.3– 23.5 µm; overall range ca 17.5–27.5 µm.
4. Growth Temperatures
Optimum temperature for growth on 24° C. Upper limit for growth 30° C with minimal growth at 3° C.
5. Growth Characteristics in Culture
On CA Phytophthora alni subsp. uniformis has an irregular appressed colony, often with a little woolly aerial mycelium in the colony centre but submerged growth at the edge
6. Distinguishing Characteristics
In contrast to the other subspecies of P. alni, subsp. uniformis produces oogonia with a smooth surface. Chromosome number ca 11–13 (inferred karyotype ca 2n+2). ITS sequence unique: GenBank accession AF139367, AY689134–5. Isozyme alleles at Mdh-1, Mdh-2 and Gpi homozygous viz. Mdh-1: 87/87; Mdh-2: 100/100; Gpi: 93/93.
Associated with root and collar rot of riparian, nursery and shelterbelt Alnus glutinosa and other Alnus species, including A. incana and A. cordata. Present known distribution: Sweden, Latvia, Germany, Austria, Italy, Hungary. Probably present in or spreading to other parts of Europe. In some locations, such as southern Germany, overlapping with other P. alni subspecies and varieties.
Brasier, C. M., Kirk, S. A., Delcan, J, Cooke, D. E. L., Jung, T And Man In’t Veld, W. A. 2004. Phytophthora alni sp. nov. and its variants: designation of emerging heteroploid hybrid pathogens spreading on Alnus trees. Mycol. Res. 108: 1172–1184
Ioos, R., Andrieux, A., Marcais, B., & Frey, P. (2006). Genetic characterization of the natural hybrid species Phytophthora alni as inferred from nuclear and mitochondrial DNA analyses. Fungal Genetics and Biology 43:511–529.
Ioos, R., Andrieux, A., Marcais, B., and Frey, P. 2007. New Hypothesis on the origin of the interspecific hybrid Oomycete Phytophthora alni. Pages 61-62. in: Fourth Meeting of the IUFRO Working Party S07.02.09 E. M. Goheen, and S. J. Frankel, eds. USDA-FS PSW-GTR-221, Monterey, CA August, 26, 2007.
This species page was adapted from Brasier et al. (2004).
Isolate list