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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).
[ Click the tree to enlarge it. ]
Phytophthora mirabilis Galindo & H.R. Hohl 1986 (Oomycetes, Pythiales)
Phytophthora infestans f. sp. mirabilis E.M. Möller & De Cock 1993
Notes: According to Goodwin et al. (1999), the name Phytophthora infestans var.mirabilis was published by Servin in 1958, but we could not locate the publication, and could not confirm that this name was validly published.
Distribution: North America (Mexico).
Substrate: Leaves.
Disease Note: Leaf blight.
Host: Mirabilis jalapa (Nyctaginaceae).
Supporting Literature:
Erwin, D.C., and Ribeiro, O.K. 1996. Phytophthora Diseases Worldwide. APS Press, St. Paul, Minnesota, 562 pages.
Galindo-A, J., and Hohl, H.R. 1985. Phytophthora mirabilis, a new species of Phytophthora. Sydowia 38: 87-96
Goodwin, S.B., Legard, D.E., Smart, C.D., Levy, M., and Fry, W.E. 1999. Gene flow analysis of molecular markers confirms that Phytophthora mirabilis and P. infestans are separate species. Mycologia 91: 796-810
Kroon, L.P.N.M., Bakker, F.T., van den Bosch, G.B.M., Bonants, P.J.M., and Flier, W.G. 2004. Phylogenetic analysis of Phytophthora species based on mitochondrial and nuclear DNS sequences. Fungal Genet. Biol. 41: 766-782
Updated on Mar 20, 2006
P. mirabilis is classified in group IV (Stamps et al. 1990). Sporangia are illustrated in Figure 1. See Tables 4.2 and 4.3 in Phytophthora Diseases Worldwide (Erwin and Ribeiro 1996) for tabular keys.
1. Sporangia
P. mirabilis isolates produce sporangia on infected leaves that are ellipsoid, caducous with short pedicels, and semipapillate. The average length of sporangia is 33.7 µm, range 26.4 to 38.5 µm, compared with a length of 28.8 µm, range 22.0 to 39.6 µm, for sporangia of P. infestans. Breadth data were not given by Galindo and Hohl (1985), but the length-breadth ratio was given as 1.9:1. Sporangiophores are compound sympodial with indeterminate branches.
2. Chlamydospores
Chlamydospores have not been reported.
3. Sex Organs
Paired A1 and A2 types (heterothallic) produce globose, smooth-walled oogonia, 26.4 µm in diameter, containing smooth-walled, colorless oospores, 21.3 µm in diameter. Antheridia are amphigynous and average 13.8 x 11.8 µm. A1 and A2 mating types occur in the field at a ratio of about 1:1.
4. Distinguishing Characteristics
All P. mirabilis isolates grow well on a synthetic medium containing nitrate as the nitrogen source, but P. infestans isolates do not (Hohl 1975, 1983). P. mirabilis is pathogenic on detached leaves of M. jalapa but not on leaves of potato or tomato. All except one of 12 P. mirabilis isolates showed esterase activity, but isolates of P. infestans did not. The P. mirabilis isolates tolerated the anti-Pythium fungicide hymexazole, but P. infestans did not (Galindo and Hohl 1985). See Chapter 2 in Phytophthora Diseases Worldwide (Erwin and Ribeiro 1996) for a discussion of hymexazole, a fungicide that is toxic to most Pythium species but allows most Phytophthora species to grow.
Sporangia of P. mirabilis are larger than those of P. infestans (length 34 versus 29 µm for P. infestans); oospores (diameter 22 versus 30 µm) and oogonia (diameter 30 versus 38 µm) are smaller than those of P. infestans. The sporangia of P. mirabilis are predominantly ellipsoid and thus have a greater length-breadth ratio (1.9:1) than P. infestans (1.7:1) (Galindo and Hohl 1985). The basal swelling at the point of the sporangium attachment is similar to that of P. infestans (see Chapter 4, Figure 4.6 in Phytophthora Diseases Worldwide (Erwin and Ribeiro 1996]). P. mirabilis differs from other members of group IV, P. colocasiae, P. hibernalis, and P. ilicis, by the production of compound sympodial sporangiophores and typical basal swellings (similar in this respect to P. phaseoli and P. infestans). P. mirabilis is heterothallic, but P. phaseoli is homothallic (Galindo and Hohl 1985). Despite the differences between P. infestans and P. mirabilis, Moller et al. (1993) consider P. mirabilis to be a forma specialis of P. infestans on the basis of mtDNA RFLP similarities.
Nomenclature information was provided by the the Systematic Botany and Mycology Laboratory in USDA-ARS.
Isolate list