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Molecular re-evaluation of Phytophthora taxa collected over the past three decades from natural ecosystems in Western Australia

Stukely, M., Hardy, G., White, D., Webster, J., Ciampini, J. and Burgess, T.I. (2008) Molecular re-evaluation of Phytophthora taxa collected over the past three decades from natural ecosystems in Western Australia. In: 3rd International Phytophthora and Pythium Workshop: Integration of traditional and modern approaches for investigating the taxonomy and evolution of Phytophthora, Pythium and related genera, 23 - 24, Turin, Italy.

Abstract

Phytophthora cinnamomi has had a huge impact on natural ecosystems in Western Australia. For 29 years the extent of the disease in native forests has been mapped based on large-scale aerial photography, with validation of observations involving the routine testing of soil and root samples for the presence of the pathogen. In addition to P. cinnamomi, six other morphological species have been reported from native ecosystems in Western Australia: P. citricola, P. megasperma, P. cryptogea, P. drechsleri, P. nicotianae and P. boehmeriae. Within the collection there were many isolates that were difficult to identify based on morphology and as more Phytophthora species have been described with similar morphology it was realised that molecular identification of some of the morphological species was required. Thus, the internal transcribed spacer (ITS) region of the rDNA gene has been amplified and sequence data compared to that of known species. Based on phylogenetic analysis, nine potentially new and undescribed taxa can be distinguished. In addition P. inundata, P. gonapodyides, and P. sp. asparagi and P. sp. niederhauseria were identified based on sequence data. Several of the new species are morphologically indistinguishable from known species (eg P. citricola, P. drechsleri, P. megasperma). In some cases the new taxa are indeed most closely related to the known species (eg P.sp. 4 and P. citricola). However, the DNA sequences of other new taxa show that they are not closely related to the morphologically similar species (eg P.sp. 3 and P. drechsleri, P.sp. 9 and P. megasperma). Most of the new species have been associated with dying Banksia spp. whilst P.sp. 2 and P.sp. 4 have also been isolated from Eucalyptus marginata (jarrah). Some species (eg P.spp. 3, 6 and 7) appear to have limited distribution, whilst others (eg P.sp.4) are more widespread. Further work is planned to describe the new taxa and to test their pathogenicity.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Phytophthora Science and Management
School of Biological Sciences and Biotechnology
Notes: Poster abstract
URI: http://researchrepository.murdoch.edu.au/id/eprint/7096
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