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Continent-wide clonal lineages of Phytophthora cinnamomi show frequent mitotic recombination

Dobrowolski, M.P., Tommerup, I.C., Shearer, B.L. and O'Brien, P.A. (2003) Continent-wide clonal lineages of Phytophthora cinnamomi show frequent mitotic recombination. In: Phytophthora in Forests and Natural Ecosystems: 2nd International IUFRO Working Party 7.02.09 Meeting, 30 September - 5 October, 2001, Albany, Western Australia.


Genetic studies of Phytophthora cinnamomi using isozymes have revealed low levels of diversity suggesting, though not proving, clonality in a large proportion of worldwide populations (1). In Australia, only three isozyme types (representing both mating types) are found with no evidence for sexual recombination (2). Using microsatellite markers, we have shown that these isozyme types are clonal lineages of P. cinnamomi and that these same lineages are found elsewhere in the world (3). Our study used 647 isolates from three intensively and hierarchically sampled P. cinnamomi disease fronts located in south-west Australia. In addition 133 isolates from an Australia-wide culture collection and 27 isolates from elsewhere in the world were analysed with four microsatellite markers. One disease front contained all three clonal lineages within close proximity in soil and plant tissue but no sexual recombinant isolates were found, even with very intensive sampling. However, within these clonal lineages we frequently found evidence for mitotic recombination (mitotic crossing over). This mechanism for producing genetic variation may explain phenotypic variation known to occur within the identified clonal lineages.

Item Type: Conference Item
Murdoch Affiliation(s): School of Biological Sciences and Biotechnology
Notes: In: JA McComb, GE StJ Hardy and IC Tommerup (eds), 'Phytophthora in Forests and Natural Ecosystems'. 2nd International IUFRO Working Party 7.02.09 Meeting, Albany, W. Australia 30th Sept - 5th Oct 2001
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