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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 gibbosa T. Jung, M.J.C. Stukely & T.I. Burgess 2011 (Oomycetes, Pythiales)
Distribution: Australia.
Substrate: Soil associated with dying plants, roots.
Supporting Literature:
Jung, T., Stukely, M.J.C., Hardy, G.E.St.J., White, D., and Paap, T. 2011. Multiple new Phytophthora species from ITS Clade 6 associated with natural ecosystems in Australia: evolutionary and ecological implications. Persoonia 26: 13-39.
Updated on Aug 26, 2011
Phytophthora gibbosa T. Jung, M. J. C. Stukely & T. I. Burgess is a rarely encountered species from the south-west of Western Australia. It belongs to the growing group of Clade 6 Phytophthoras and phylogenetically it is most closely related to P. gregata and P. taxon raspberry, an undescribed species from Europe. Like these species it has been isolated from soil associated with dying plants.
1. Sporangia
Sporangia are rarely observed on solid agar but are produced abundantly in non-sterile soil extract. Sporangia were typically borne terminally on unbranched sporangiophores, less frequently in lax sympodia. Sporangia are non-caducous and generally nonpapillate (Fig. 1c-d) although some semipapillate (Fig. 1a-b) sporangia are observed. Sporangial shapes range from ovoid (Fig. 1a-b) and elongated ovoid to ellipsoid (Fig. 1d) and, less frequently, pyriform, obpyriform (Fig. 1c). Sporangia proliferated either externally or internally in an extended way (Fig. 1e), never nested. Sporangial dimensions average 48.8 ± 9.6 × 30.8 ± 5.4 μm (overall range 24.8 –71.1 × 17.4 – 48.0 μm). The length/breadth ratio of the sporangia average 1.58 ± 0.15. Hyphal swellings were regularly formed which, according to their morphology, were most likely undeveloped sporangia which had failed to form a basal septum and continued to grow at their apex (Fig. 1f).
2. Chlamydospores
Chlamydospores not observed.
3. Sex Organs
P. gibbosa is homothallic and readily produced oogonia in single culture on V8 agar within 4 days (Fig. 2). Oogonia averaged 38.1 ± 5.4 μm. Oogonia were borne terminally or laterally, had either wavy edged to ornamented gibbous (Fig. 2b-d) or smooth walls (Fig. 2a) and were usually globose, subglobose or slightly excentric. In all isolates oogonial walls often turned golden-brown to bronze-brown while ageing. Oospores (31.4± 4.6 μm ) were always aplerotic, usually globose and contained a large ooplast The oospores were relatively thick-walled (3.17 ± 0.69 μm), with a mean oospore wall index of 0.49 ± 0.06. The antheridia were exclusively amphigynous and were usually formed terminally or laterally, and were rarely intercalary.
4. Growth Temperatures
Radial growth rates on V8 agar at optimum temperature (30 °C) was 6.3 ± 0.3 mm/d. Isolates were unable to grow at 35 °C, and did not resume growth when plates incubated for 7 d at 35 °C were transferred to 20 °C.
5. Growth Characteristics in Culture
All isolates of P. gibbosa isolates formed similar uniform colonies with aerial mycelium on the four different types of media (Fig. 3).
6. Distinguishing Characteristics
Phytophthora gibbosa can be easily differentiated from all other species from ITS Clade 6 by the production of ornamented (gibbous) oogonia in single culture. In addition, it can be separated from P. gregata and P. taxon raspberry by the lack of nested proliferation of sporangia.
7. Type isolate
AUSTRALIA, Western Australia, Scott River ironstones, from rhizosphere soil of dying Acacia pycnantha, 2009, VHS, holotype MURU 461 (dried culture on V8A, Herbarium of Murdoch University, Western Australia), cultures ex-type CBS127951 and VHS21998; ITS, ß-tubulin, HSP90, cox1 and NADH, and sequence GenBank HQ012933, JN547596, HQ012892, HQ012846 and JN547683 respectively, MycoBank MB518763.
Pathogenic on Acacia pycnantha, Xanthorrhoea gracilis and Grevillea sp.
Jung, T., Stukely, M. J. C., St. Hardy, G. E., White, D., Paap, T. Burgess, T. I., 2011. Multiple new Phytophthora species from ITS Clade 6 associated with natural ecosystems in Australia: evolutionary and ecological implications. Persoonia 26: 13–39.
This page was written by Treena Burgess Centre for Phytophthora Science and Management, Murdoch University, Australia.
Isolate list