Suppression of Phytophthora cinnamomi by the root exudates of Acacia pulchella

Jayasekera, A.U., McComb, J.A., Hardy, G.E.St.J. and Shearer, B.L. (2006) Suppression of Phytophthora cinnamomi by the root exudates of Acacia pulchella. In: Proceedings of the 3rd International (IUFRO) Conference on Phytophthora in Forests and Natural Ecosystems, 11 - 18 September 2004, Freising, Germany.

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Abstract

The potential fungitoxic qualities of the root exudates of A. pulchella var. goadbyi on P. cinnamomi were tested. Techniques were developed to ascertain the mycelial inhibition and chlamydospore suppression of P. cinnamomi to a range of concentrations of exudates which were collected from in vitro grown A. pulchella plants. The controlled conditions under which the experiments were conducted prevented other environmental factors interfering with the effects of root exudates on P. cinnamomi. This was an important goal and the system enabled continuous collection of root exudates for laboratory bioassays. Bioassay procedures consisted of incubating mycelial disks of P. cinnamomi in a range of concentrations of A. pulchella exudates incorporated into a basal liquid medium. Significant inhibition of, P. cinnamomi mycelial growth was recorded in the solutions with A. pulchella var. goadbyi root exudates compared to the control solutions. The root exudates were fractioned with hexane and the bioassays conducted with the chlamydospore suspensions showed collapse and low germination of chlamydospores in the A. pulchella exudates compared to the controls.