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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 ipomoeae Flier & Grünwald was recovered from blighted foliage of Ipomoea longipedunculata in the Toluca Valley of central Mexico. In phylogenetic analysis it is in clade 1C closely related to P. infestans.
1. Sporangia
Sporangiophores aerial, sparsely formed on rye agar with compound-sympodial and intermediate branches, with swellings where sporangia emerge. Sporangia semipapillate, ellipsoid or semi-ovoid, caduceus with short pedicel, on average 39 µm long (range 35 - 47.5 µm), with a length:width ratio of 1.9, germinating directly with germ tubes or indirectly with 4 - 8 zoospores. Zoospores were
readily released (within 4 hrs) from sporangia in a watery suspension at 10° C.
2. Chlamydospores
Chlamydospores not formed
3. Sex Organs
Homothallic, amphigynous antheridia, average length 19 µm, ratio of length:width 1.3. Oogonia smooth-walled, average diameter 32.5 µm, with tapered base. Oospores smooth-walled, rarely tinted yellow, almost filling the oogonial cavity, average diameter 28.8 µm.
4. Growth Temperatures
Minimum growth at approx 11° C, optimum at 20° C and maximum at 25° C.
5. Growth Characteristics in Culture
Radial growth rates of approx 10 mm/day on solid agar media such as Rye A agar (RA), Cherry decoction agar (CA), Potato Dextrose Agar (PDA) and Oatmeal Agar (OA). Restricted radial growth of approx 5 mm/d was observed on Minimal Medium Agar (MM). Growth inhibition was observed on V-8 Agar (V8) with an average radial growth rate of 0.5 mm/d. Colonies on MM exhibited a petaloid to rosaceous colony morphology while growth on nutrient-rich media like RA, CA, PDA and OA resulted in rather undefined fluffy aerial growth of mycelium. Hyphae were non-septate and moderately or freely branching with a hyphal diameter ranging from 3.8 to 7.5 µm. Hyphal swellings on solid agar media were rarely observed.
6. Distinguishing Characteristics
The colony growth rate of isolates collected from Ipomoea is somewhat higher than compared to these three species, while sporangia dimensions are notably larger than those reported for the three group IV species examined. The isolates differ from most other species in taxonomic group IV by the presence of typical basal swellings on the sympodial sporangiophores which they only share with P. phaseoli, P. mirabilis and P. infestans. Sex organs found in cultures of P. ipomoeae are similar to those of P. infestans, P. mirabilis and P. phaseoli, the average oospore diameter being larger as compared to P. mirabilis and P. phaseoli. The isolates share the combination of amphigyny and homothallism with P. phaseoli.
Phytophthora ipomoeae is host specific for the range of hosts tested in Flier et al. (2002). P. ipomoeae isolates rarely formed small, necrotic (<2 mm diameter) spots on potato and tomato leaflets in the detached leaflet bioassays. However, no sporangiophores were observed during the incubation period of 14 days. No disease symptoms were observed when tuber slices of potato cv. `Bintje\' or leaves of Mirabilis jalapa and sweet potato (Ipomoea batata) were inoculated. Inoculation with either of the two P. ipomoeae isolates examined in Flier et al. (2002) on I. longipedunculata led to sporulating lesions. Isolates of P. infestans were found pathogenic on both potato and tomato, on which abundant sporulation occurred after 5 - 8 days after inoculation. Both potato and M. jalapa leaf tissues were colonized by P. mirabilis, isolate PIC 99111 causing necrotic flecking and small sporulating lesions on cv. Bintje leaflets 10 days after inoculation. No disease symptoms were observed when P. phaseoli was inoculated on the host plant species included.
lier, W. G., Grünwald, N. J., Kroon, L. P. N. M., Van Den Bosch, T. B. M., Garay-Serrano, E., Lozoya-Saldana, H., Bonants, P. J. M. and Turkensteen, L. J. 2002. Phytophthora ipomoeae sp. nov., a new homothallic species causing leaf blight on Ipomoea longipedunculata in the Toluca Valley of central Mexico. Mycol. Res. 106: 848-856.
Nomenclature information was provided by the the Systematic Botany and Mycology Laboratory in USDA-ARS. This species page was adapted from Flier et al. (2002).
Isolate list