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Bentley, Australia

Shearer B.L.,Delivery Center | Michaelsen B.J.,Delivery Center | Somerford P.J.,Delivery Center | Williams M.,Delivery Center
Australasian Plant Pathology | Year: 2014

The effect of forest environments on the expression of intraspecific resistance in Eucalyptus marginata to Phytophthora cinnamomi was determined in three Jarrah Forest bioregion provenances. Temperature was varied by inoculating in summer and winter. A nested design was used to partition variation between inoculation time, between genotypes within provenances and between provenances. Intraspecific variation in the response of E. marginata to P. cinnamomi in the forest environments occurred as resistant-susceptibility continua from a few resistant to a few highly susceptible trees. Rates of lesion extension and girdling were significantly less for the winter than the summer inoculation. The distributions of rates of lesion extension and girdling were positively skewed for the winter inoculation. Coppice completely girdled by P. cinnamomi was 4-7 % in the winter inoculation compared to 30-73 % in the summer inoculation. Regional variation in intraspecific resistance in E. marginata to P. cinnamomi may account for the Park Block provenance having least girdled coppice by the pathogen and the greatest proportion of trees with the slowest rates of lesion development, compared to the other two provenances. Resistance to P. cinnamomi in native flora of south-western Australia has probably evolved as a fortuitous side effect of ecological fitting of functional traits that evolved in response to different sets of biotic and abiotic conditions that occurred before the introduction of the pathogen. Sowing seed from resistant E. marginata into communities would be an option for reactive restoration of infested areas or proactive intervention in threatened healthy communities, to ensure their survival and the conservation of ecosystem genetic and functional diversity. © 2014 Australasian Plant Pathology Society Inc. Source

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