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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 arenaria A. Rea, M. Stukely & T. Jung has been isolated in Western Australia from kwongan heath-land stands since the early 1980s (Burgess et al. 2009, Rea et al. 2011), but was misidentified as P. citricola. With the exception of one isolate from Bunbury (south-west coast) P. arenaria has been isolated exclusively from the northern sand plains. Most isolates were associated with dead or dying Banksia or Eucalyptus species; however, isolates were also recovered in association with asymptomatic Banksia and Eucalyptus species. The first isolation of this taxon was from soil in native kwongan vegetation near Kalbarri in 1986. Phytophthora arenaria has thick oospore walls and physiological characteristics that appear to be adaptations favouring survival in the harsh kwongan ecosystem suggesting that this species may be endemic to Western Australia. However, the most closely related species is P. alticola a species described from South Africa and the origin of both species requires further examination.
1. Sporangia
Papillate persistent sporangia were abundantly produced in soil extract water on simple sporangiophores frequently with globose swellings close to the sporangial base. Sporangial apices were often pointed. Although predominantly ovoid (Fig. 1a), a range of sporangial shapes was observed including broadly ovoid, elongated ovoid, obpyriform (Fig. 1b), and asymmetrically mouse-shaped. Bipapillate, tripapillate and bilobed sporangia were also observed (Fig. 1d). Sporangia often had special features including laterally displaced apices, a large vacuole, lateral attachment of the sporangium (Fig. 1b), a conspicuous basal plug, hyphal extensions, and intercalary formation of the sporangium. Sporangia from 10 isolates averaged 31.8 ± 4.6 µm in length and 23.7 ± 3.5 µm in width, with narrow exit pores of 6.0 ± 1.0 µm and a length:breadth ratio of 1.4 ± 0.17. Catenulate, globose to sub-globose hyphal swellings, some with radiating hyphae, were formed in non-sterile soil extract water (Fig. 1e)
2. Chlamydospores
Chlamydospores not observed.
3. Sex Organs
Phytophthora arenaria is homothallic and readily produced oogonia in single culture on CA and V8A, containing oospores which matured within 14 to 21 days. Oogonia from nine isolates averaged 25.3 ± 2.2 µm with isolate means ranging from 24.3 to 28.1 µm. Oogonia often had a slightly wavy outer wall and turned dark-brown to bronze-brown with maturity (Fig. 2b-c). Oogonia sometimes had a tapering base or were excentric. Oospores were aplerotic in all isolates and contained ooplasts when semi-mature to mature (Fig. 2a). Some oospores were excentric. Oospores averaged 22.3 ± 1.8 µm in diameter with isolate means ranging from 21.4 to 23.9 µm. Oospore walls were thick (2.3 ± 0.34 µm). The oospore wall index was 0.50 ± 0.05 µm, with isolate means ranging from 0.49 to 0.52 µm. Antheridia were exclusively paragynous and usually club-shaped, with some having finger-like projections, and were attached to the oogonium close to the oogonial stalk or at an angle of up to 90° from the oogonial stalk. Antheridia averaged ca 11.2 ± 1.7 x 8.4 ± 1.3 µm.
4. Growth Temperatures
It grows on CA agar at 15-32.5°C with an optimum near 30°C (radial growth rate 6.5 ± 0.49 mm/d). No growth occurred at 10 or 35°C, but neither temperature was lethal.
5. Growth Characteristics in Culture Media
All P. arenaria isolates produced colonies with a radiate morphology on V8A and CA (Fig. 3a-b). On MEA and PDA some isolates also produced radiate patterns while others showed irregular colony morphologies (Fig. 3c-d).
6. Distinguishing Characteristics
A summary of decisive morphological and physiological characters discriminating P. arenaria from the closely related species P. taxon arenaria-like, P. alticola, P. cactorum and P. quercetorum is given in Rea et al. (2011). Briefly, the closest species to P. arenaria based on morphology are P. cactorum and P. quercetorum, all belonging to Waterhouse group I. Phylogenetically, the closest species to P. arenaria are P. quercetorum and P. alticola. Major differences between P. arenaria and P. cactorum are the wavy outer oogonial wall in P. arenaria and the production of caducous sporangia in sympodia by P. cactorum. Phytophthora arenaria can easily be distinguished from P. alticola by the lack of amphigynous antheridia and caducous sporangia, and by its lower maximum temperature for growth. Phytophthora quercetorum is separated from P. arenaria by having a lower optimum temperature for growth, thinner oospore walls and on average larger sporangia formed in sympodia
7. Type isolate
AUSTRALIA, Eneabba, isolated from soil sample collected beneath asymptomatic Eucalyptus drummondii growing in native kwongan vegetation, February 2009, T. Jung. holotype: MURU 455 (dried culture on V8A in the herbarium of Murdoch University, Western Australia). ex-type culture CBS 127950. rDNA ITS (HQ013219), coxI (HQ013203). MycoBank MB518792.
Causes patchy deaths of Banksia spp. in kwongan vegetation. Banksia littoralis, B. attenuata, B. sphaerocarpa, B. hookeriana, B. menziesii, Hibbertia hypericoides, and Eucalyptus drummondii are hosts. Management of infested material in nurseries. Control of rare or endangered flora can be achieved through the use of phosphite applications.
Commonly detected by baiting of rhizosphere soil, also isolated by direct plating of damaged roots or stem cankers on PARPNH selective medium.
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.
Maseko, B., Coutinho, T. A., Burgess, T. I., Wingfield, B. D., Wingfield, M. J. 2007. Two new species of Phytophthora from South African eucalypt plantations. Mycological Research 111: 1321-1338.
Rea, A., Burgess, T. I., Hardy, G. E. S., Stukely, M. J. C., Jung, T. 2011. Two novel species of Phytophthora associated with episodic dieback of kwongan vegetation of south-west Western Australia. Plant Pathology 60: 1055-1068
The contribution by Treena Burgess, Centre for Phytophthora Science and Management, Murdoch University, Australia, in preparing this species page and providing images is gratefully acknowledged.
Isolate list