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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 elongata A. Rea, M. Stukely & Jung has been isolated in Western Australia from natural forest and heath-land stands since the early 1980s (Burgess et al. 2009, Rea et al. 2010), but was misidentified as P. citricola. It has been isolated in the northern jarrah forest of Western Australia from the roots and collars of dead and dying Eucalyptus marginata and occasionally Corymbia calophylla in rehabilitated bauxite mine-pits. It has also been associated with dead and dying plants of several mid- and understorey species in the northern and southern jarrah forest – Banksia grandis, Leucopogon propinquus, Dryandra squarrosa and an Andersonia sp., as well as the monocotyledonous Xanthorrhoea preissii, X. gracilis and Patersonia xanthina. The pathogenicity of P. elongata to E. marginata and Banksia spp. has been demonstrated. It’s distribution in Western Australia is more limited than that of P. cinnamomi and the recently described P. multivora. Due to the uniformity of the ITS DNA and cox1 sequence data in Western Australia, P. elongata may be the result of a recent clonal introduction. Several recent papers have compared species within the P. citricola complex, including P. elongata. Sequence data for additional gene regions (EF1- and NADH) were provided by Bezuidenhout et al. (2010).
1. Sporangia
Semipapillate persistent sporangia of P. elongata are abundantly produced in non-sterile soil extract water in mostly lax sympodia or on simple sporangiophores. Up to 8-10 sporangia per sporangiophore are observed although there are usually fewer. Sporangial shapes vary widely, ranging from ovoid (Fig. 1a) and ovoid-obpyriform to obpyriform (Fig. 1b) and limoniform (Fig. 1c). Sporangial proliferation is external and often occurred immediately below the old sporangium (Fig. 1d). In all isolates the sporangiophore occasionally widened towards the base of the sporangium. Basal swellings are sometimes observed on sporangiophores. Sporangial apices are usually flat but could occasionally be pointed. Sporangia often have special features such as curved or displaced apices a large vacuole or a conspicuous basal plug that protrude into the empty sporangium. Normal-sized sporangia average 45.8 ± 6.3 µm in length and 28.4 ± 3.5 µm in width, with exit pores 7 ± 1.1 µm wide. In addition, all isolates of P. elongata also produce some markedly elongated sporangia with elongated obpyriform, ampuliform, limoniform or distorted shapes (Fig. 1e) which average 58.2 ± 12.7 µm in length and 24.5 ± 4.3 µm in breadth. Length/breadth ratio for normal-sized sporangia was 1.6 ± 0.2 , whilst for elongated sporangia it was 2.4 ± 0.5. Some sporangia could be seen germinating directly (Fig. 1f).
2. Chlamydospores
Chlamydospores not observed.
3. Sex Organs
P. elongata is homothallic and readily produced oogonia in single culture on V8 agar, containing oospores which mature within ca 2 weeks (Fig. 2). Oogonia from 5 isolates averaged 31.2 ± 3.2 µm with isolate means ranging from 30.5 to 33.4 µm. Many oogonia had a tapering base. In all isolates some oogonia have a very long stalk (up to 79.7 µm), which can be either thick or thin and is usually curved (Fig. 2d-e). Both plerotic and aplerotic oospores occur in all isolates (Fig. 2). They average 27.4 ± 3.3 µm diameter with isolate means ranging from 26.7 to 29.7 µm. Oospore walls are moderately thick (2.27 ± 0.36 µm) and often turned golden-brown when ageing. The oospore wall index was 0.42 ± 0.05 µm, with isolate means ranging from 0.39 to 0.44 µm. Irregular hyphal swellings were formed by all isolates. Antheridia were exclusively paragynous, usually club-shaped, with some having a short hyphal extension, and were usually attached either close to the oogonial stalk, or at an angle of up to 90°.
4. Growth Temperatures
It grows on CA agar at 5-32.5°C with an optimum near 25°C (radial growth rate 6.29 ± 0.21 mm/d). No growth occurred at 32.5°C.
5. Growth Characteristics in Culture
On all media V8A (Fig. 3a), CA(Fig. 3b), MEA (Fig. 3c) and PDA (Fig. 3d) isolates produced colonies with petaloid morphology.
6. Distinguishing Characteristics
A summary of decisive morphological and physiological characters discriminating P. elongata from the closely related species P. bisheria, P. frigida and P. multivesiculata is given in Rea et al. (2010). Briefly, like P. elongata, P. bisheria produces both large distorted sporangia as well as ovoid-obpyriform and obpyriform sporangia, which may have a large vacuole. P. elongata can be distinguished from P. bisheria by the absence of bipapillate sporangia and globose sporangial shapes, by considerably higher growth rates, the occasional presence of long oogonial stalks in all isolates, and different colony growth patterns. P. elongata can be easily distinguished from P. frigida by the production of oogonia with paragynous antheridia in single culture, and persistent semipapillate sporangia which on average are much larger, the occurrence of elongated sometimes distorted sporangia which may have a vacuole, the occasional presence of long oogonial stalks in all isolates, the absence of chlamydospores, different colony growth patterns and higher cardinal temperatures. Similarities between P. multivesiculata and P. elongata include the production of ovoid and obpyriform semipapillate sporangia which may directly germinate and form another sporangium. P. elongata can be separated from P. multivesiculata by the occurrence of elongated sometimes distorted sporangia which may have a vacuole, the absence of nonpapillate or bipapillate sporangia, the occasional presence of long oogonial stalks in all isolates, the absence of amphigynous antheridia and chlamydospores, and the production of distinct colony growth patterns.
P. elongata does not produce sporangia with more than one papilla, and does not display the range of distorted sporangial shapes typical of P. citricola and produced occasionally by P. multivora. P. elongata produces markedly elongated sporangia with large vacuoles, and long oogonial stalks which are not observed in P. citricola and P. multivora. Furthermore, oospores of P. elongata have significantly thicker walls and a higher oospore wall index than those of P. citricola. P. multivora can also be distinguished from P. elongata by its higher oospore wall index, the lack of excentric and elongated oogonia, the absence of long oogonial stalks and hyphal swellings typical of P. elongata, and the production of distinct stellate growth patterns on V8A,CMA and MEA.
7. Type isolate
AUSTRALIA, Dwellingup, from rhizosphere soil of dying Eucalyptus marginata, April 2004, M. Stukely, holotype MURU 454 (dried culture on V8A, Herbarium of Murdoch University, Western Australia), culture ex-type CBS 125799. rDNA ITS (GQ847754), coxI (GQ847764). Mycobank: MB 515142.
Numerous hosts including Eucalyptus marginata, Corymbia calophylla, Banksia grandis, Leucopogon propinquus, Dryandra squarrosa, Xanthorrhoea preissii, X. gracilis and Patersonia xanthina. Causes sudden death of Eucalyptus marginata (jarrah) in rehabilitated bauxite mine-pits. Disease managed by control of infested material in nurseries, no management practices are available under forest settings.
Commonly detected by baiting of rhizosphere soil, also isolated by direct plating of damaged roots or stem cankers on PARPNH selective medium.
Bunny, F. J. (1996) The biology, ecology and taxonomy of Phytophthora citricola in native plant communities in Western Australia. PhD. thesis, Murdoch University, Perth, Australia.
Burgess, T. I., Webster, J. L., Ciampini, J. A., White, D. W., Hardy, G. E. S. J., Stukely, M. J. C. (2009) Re-evaluation of Phytophthora species isolated during 30 years of vegetation health surveys in Western Australia using molecular techniques. Plant Disease 93: 215-223.
Rea, A., Jung, T., Burgess, T. I., Stukely, M. J. C., Hardy, G. E. S. 2010. Phytophthora elongata sp. nov. a novel pathogen from the Eucalyptus marginata forest of Western Australia. Australasian Plant Pathology 39: 477–491.
Stukely. M. J. C., Webster, J. L., Ciampini, J. A., Kerp, N. L., Colquhoun, I. J., Dunstan, W. A., Hardy, G. E. S. (2007) A new homothallic Phytophthora from the jarrah forest in Western Australia. Australasian Plant Disease Notes 2: 49-51.
This page was written by Treena Burgess, Centre for Phytophthora Science and Management, Murdoch University, Australia.
Isolate list