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 Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).
[ Click the tree to enlarge it. ]
Phytophthora lacustris Brasier, Cacciola, Nechwatal, Jung & Bakonyi is the formal taxonomic description of the provisional Phytophthora species referred to as P. taxon Salixsoil (Brasier et al. 2003). Based on morphology isolates of this species were often initially identified as P. gonapodyides (Brasier et al. 1993) but later molecular analysis using the ITS region confirmed they represented a different species in clade 6, hence the provisional name P. taxon Salixsoil, referring to its first isolation from diseased roots of a Salix sp. It has been reported from forest ecosystems (soil) or rivers and lakes (water, sediment, plant debris) in the UK, Cech Republic, Denmark, Italy, Germany, Hungary, Poland, Switzerland, Turkey, Iran, the USA (Alaska, western Oregon and elsewhere), Western Australia, New Zealand and China. It obviously has also entered the nursery production system in Europe, and was detected in citrus plantations in India. Together with the newly described Phytophthora riparia (="P. New species 2" in Reeser et al. 2011), it was shown to be involved in the formation of a hybrid taxon that has been detected in the USA (isolate EBE1.8.27 in Hansen et al., 2012; P. riparia ITS sequence, β-tubulin of both parents and cox1 of P. lacustris).
1. Sporangia
Sporangia are not formed in solid agar media but are abundantly produced in nonsterile soil filtrate. Non-caducous sporangia were terminally produced on mostly unbranched sporangiophores, they were non-papillate, ovoid or obpyriform with a mean size of 41.0 X 29.5 µm for the type culture (range 30– 55 X 22.5–37.5 µm), and a mean LB ratio of 1.39 (range 1.20– 1.62). They were mostly proliferating internally, nested or extended (Fig. 1), sometimes externally with new sporangiophores emerging just below the mature sporangium. Hyphal swellings rarely produced, subglobose or ellipsoid, 12–18 X 7.5–10 µm in size.
2. Chlamydospores
Not observed
3. Sex Organs
Not observed, but isolates have induced gamitangial formation in some A2 isolates of other species, e.g. P. cambivora (but the P. lacustris isolate remained sterile, referred to as having a "silent A1 mating type").
4. Growth Temperatures
Colonies growing between 3 and 37°C with optimum growth at 28–30°C; daily growth rate on CA at 25°C 5.8 mm for the type culture.
5. Growth Characteristics in Culture
Colonies on CA with petaloid or chrysanthemum-like patterns, submerged at the margins, with appressed or little aerial mycelium towards the centre of the plate. Cultures on malt extract agar have a similar pattern (Fig. 2)
6. Distinguishing Characteristics
While there is some similarity of morphological features with P. gonapodyides on average the sporangial size of P. lacustris is smaller than of P. gonapodyides (44.8 X 30.9 µm for 34 isolates of P. lacustris examined compared to 52.6 X 36.3 µm for P. gonapodyides), although the length/breadth ratio is similar (1.44 compared to 1.46, respectively). Likewise, P. lacustris has a higher optimum and maximum growth rate than P. gonapodyides (optimum from 28-33°C with maximum of 36°-37° C compared to optimum of 24-26° C and maximum of 34-35° C, respectively).
This species has been recovered from diseased roots and stem bases of Alnus glutinosa, Fraxinus excelsior, Prunus spp. and Salix matsudana, often after flooding. In addition, in laboratory pathogenicity assays it proved to be moderately aggressive to stems/ twigs of Betula pendula, Carpinus betulus, Fagus sylvatica, Quercus petraea and Salix alba. On S. alba twigs, P. lacustris caused significantly larger lesions than the closely related P. gonapodyides (Fig. 3). It was also a severe fine root pathogen of A. glutinosa and Prunus persica seedlings in greenhouse soil infestation assays with artificial flooding. Thus, in addition to its proposed role in the breakdown of plant detritus, P. lacustris may be an opportunistic fine root pathogen, in particular in (temporarily) wet or flooded habitats.
Brasier, C. M., Hamm, P. B., Hansen, E. M. 1993. Cultural characteristics, protein patterns and unusual mating behavior of Phytophthora gonapodyides isolates from Britain and North America. Mycol. Res. 97:1287-1298.
Brasier, C. M., Cooke, D. E. L., Duncan, J. M., and Hansen, E. M. 2003. Multiple new phenotypic taxa from trees and riparian ecosystems in Phytophthora gonapodyides-P. megasperma ITS Clade 6, which tend to be high-temperature tolerant and either inbreeding or sterile. Mycol. Res. 107:277-290.
Hansen, E. M., Reeser, P. W., Sutton, W. 2012. Phytophthora borealis and Phytophthora riparia, new species in Phytophthora ITS Clade 6. Mycologia: In Press. doi:10.3852/11-349
Nechwatal, J., Bakonyi, J., Cacciola, S.O., Cooke, D. E. L., Jung, T., Nagy, Z. A., Vannini, A., Vettraino, A. M., Brasier, C. M. 2012. The morphology, behaviour and molecular phylogeny of Phytophthora taxon Salixsoil and its redesignation as Phytophthora lacustris sp. nov. Plant Pathology Doi:10.1111/j.1365-3059.2012.02638.x
Reeser, P. W., Hansen, E. M., Sutton, W., Remigi, P., Adams, G. C. 2011. Phytophthora species in forest streams in Oregon and Alaska. Mycologia 103: 22-35
This species page was adapted from Nechwatal et al. (2012). The contribution of images and additional content for this page by Dr. Nechwatal is gratefully acknowledged.
Isolate list