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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).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 plurivora T. Jung & T.I. Burgess (under the identity of P. citricola) has been isolated extensively in Europe from natural forests and a variety of hosts in other parts of the world. It has been recovered from numerous host species with symptoms of high transparency and dieback of crowns, small-sized and often yellowish foliage, extensive fine root losses, root lesions, collar rots, aerial cankers and shoot dieback. Based on unique combinations of morphological and physiological characters, and using mutigene phylogeny, several species have now been resolved from the P. citricola complex; P. plurivora, P. multivora, P. pini and P. capensis with P. citricola being retained only for isolates whose morphology and sequence data is an exact match to that of the type isolate (CBS 221.88) (see references). Several recent papers have compared species within the P. citricola complex. Sequence data for additional gene regions (EF1-α and NADH) were provided by Bezuidenhout et al. (2010).
1. Sporangia
Sporangia of P. plurivora are typically borne terminally on unbranched sporangiophores or more often in irregular lax or regular dense sympodia (Fig. 1b), and some are laterally attached or intercalary (Fig. 1d). Small subglobose hyphal swelling are sometimes formed at the nodes. Sporangia are non-caducous, semipapillate, less frequently bi- or tripapillate or bilobed (Fig. 1e) and usually formed a conspicuous basal plug that protruded into the empty sporangium. Within all P. plurivora isolates sporangial shapes show a wide variation ranging from ovoid (Fig. 1a-b) or limoniform (Fig. 1c) to obpyriform, ellipsoid, or distorted shapes. Sporangia with unusual features such as lateral attachment of the sporangiophore, markedly curved apices, a widening of the sporangiophore towards the base of the sporangium (Fig. 1c) or a short hyphal extension are common in all isolates. Sporangial dimensions of seven isolates of P. plurivora averaged 47.4 ± 7.7 x 33.5 ± 5.1 µm (overall range 27.5–80.5 x 16.7–69.6 µm) with a range of isolate means of 39.6-52.3 x 28.9-38.8 µm, and a length/breadth ratio of 1.43 ± 0.19 (range of isolate means 1.25–1.61). Sporangia were produced by flooding 15 × 15 mm square agar discs taken from growing margins of 3–5 d old colonies, just over its surface, with nonsterile soil extract in 90 mm Petri dishes and incubating them in the dark at 18 – 22 °C at natural daylight.
2. Chlamydospores
Chlamydospores not observed.
3. Sex Organs
P. plurivora is homothallic. Gametangia are readily produced in single culture by all isolates on V8A within 4 d. Oogonia are borne terminally, have smooth walls and are globose to slightly subglobose with a mean diam of 28.5 ± 3.3 µm (overall range 15–37.5µm and range of isolate means 27.5 to 29.9µm) or rarely elongated with a long tapering base (Fig. 2d). Oospores are usually globose (Fig. 2a-c), but can be subglobose in elongated oogonia (Fig. 2d). Oospore wall thickness is 1.45 ± 0.35µm (range 0.4-2.5 µm), oospore wall index is 0.30 ± 0.06. The antheridia are obovoid, club-shaped or irregular, sometimes with one or more finger-like projections, and almost exclusively paragynous. Intercalary and amphigynous antheridia were only rarely observed.
4. Growth Temperatures
P. plurivora grows on V8 agar (V8A) at 5-32.5° C with an optimum near 25° C (radial growth rate 8-8.4 mm/d). Generally no growth occurred at 32.5° C.
5. Growth Characteristics in Culture
On V8A (Fig. 3a) and MEA (Fig. 3b) all isolates produced colonies with limited aerial mycelium in the centre of the colonies which have radiate to slightly chrysanthemum growth patterns, on PDA (Fig. 3c) colonies have a chrysanthemum pattern with more aerial mycelium than on the other media.
6. Distinguishing Characteristics
A summary of decisive morphological and physiological characters discriminating P. plurivora from P. citricola s. str., P. pini, P. multivora and P. inflata is given in Burgess and Jung (2009). Briefly, the most decisive characters for discriminating between P. plurivora and P. citricola s.str. are the significantly lower length/breadth ratio of P. plurivora sporangia, differences of morphological structures formed on the underside of older colonies, colony growth patterns on PDA, and higher radial growth rates of P. plurivora on MEA and PDA at 20 °C and on V8A between 20 and 30 °C. Phytophthora plurivora is also clearly different from P. citricola I and P. multivora by morphological and physiological characters.
7. Type isolate
GERMANY, Irschenberg, from root lesion of declining mature Fagus sylvatica, February 2004, T. Jung, holotype MURU 433 (dried culture on V8A, Herbarium of Murdoch University, Western Australia), culture ex-type CBS 124093. rDNA ITS (FJ665225), coxI (FJ665236), Beta-tubulin (FJ665247).
Pathogenic toward numerous woody hosts including Abies alba, Alnus glutinosa, Alnus incana, Acer platanoides, Acer pseudoplatanus, Acer saccharum, Aesculus hippocastanum, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Quercus robur, Quercus petraea, Quercus rubra, Rhododendron spp., Syringa vulgaris, Tilia spp., Tsuga canadensis, (Jung and Burgess, 2009). Recovered from roots, rhizosphere soil, basal and stem cankers and shoots of some hosts. Commonly detected by baiting of rhizosphere soil, also isolated by direct plating of damaged roots, stem cankers or shoots on PARPNH selective medium. Disease control attained by management of infested material in nurseries. No management practices are available under forest settings.
Bezuidenhout, C. M., Denman, S., Kirk, S. A., Botha, W. J., Mostert, L., McLeod, A. 2010. Phytophthora taxa associated with cultivated Agathosma, with emphasis on the P. citricola complex and P. capensis sp. nov. Persoonia 25: 32-49.
Bhat, R. G., Browne, G. T. 2007. Genetic diversity in populations of Phytophthora citricola associated with horticultural crops in California. Plant Disease 91: 1556-1563.
Burgess, T. I., Webster, J. L., Ciampini, J. A., White, D., 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.
Gallegly, M. E., Hong, C., Richardson, P. A., Kong, P. 2010. Phytophthora pini Leonian, a valid and distinct species. Phytopathology 100: S207.
Jung, T., Burgess, T. I.. 2009. Re-evaluation of Phytophthora citricola isolates from multiple woody hosts in Europe and North America reveals a new species, Phytophthora plurivora sp. nov. Persoonia 22: 95-110.
Mrazkova, M., Cerny, K., Tomsovsky, M., Holub, V., Strnadova, V., Zlatohlavek, A., Gabrielova, S., Tarouca, S. 2010. First report of root rot of pedunculate oak and other forest tree species caused by Phytophthora plurivora in the Czech Republic. Plant Disease 94: 272.
Oudemans, P. V., Förster, H., Coffey, M. D.. 1994. Evidence for distinct isozyme subgroups within Phytophthora citricola and close relationships with P. capsici and P. citrophthora. Mycological Research 98: 189-199.
Reeser, P. W., Sutton, W., Hansen, E. M., Remigi, P., Adams, G. C. 2011. Phytophthora species in forest streams in Oregon and Alaska. Mycologia 103: 22-35.
Scott, P. M., Burgess, T. I., Barber, P. A., Shearer, B. L., Stukely, M. J. C., Hardy, G. E. S. J., Jung, T. 2009. Phytophthora multivora sp. nov., a new species recovered from declining Eucalyptus, Banksia, Agonis and other plant species in Western Australia. Persoonia 22: 1-13.
Weiland, J. E., Nelson, A. H., Hudler, G. W. 2010. Aggressiveness of Phytophthora cactorum, P. citricola I, and P. plurivora from European Beech. Plant Disease 94: 1009-1014.
This page was written by Treena Burgess and Thomas Jung, Centre for Phytophthora Science and Management, Murdoch University, Australia.
Isolate list