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Open AccessAbstract

Variations in macadamia varietal susceptibility to Phytophthora multivora and P. cinnamomi

Centre for Horticultural Science, Queensland Alliance for Agriculture & Food Innovation, Queensland Alliance for Agriculture & Food Innovation, The University of Queensland, Dutton Park, Australia
Department of Agriculture and Fisheries, Dutton Park, Australia
Author to whom correspondence should be addressed.
Presented at the third International Tropical Agriculture Conference (TROPAG 2019), Brisbane, Australia, 11–13 November 2019.
Proceedings 2019, 36(1), 109;
Published: 21 February 2020
Incidence of diseases caused by various Phytophthora spp. in macadamia is increasing worldwide, often resulting in severe yield loss and death of both juvenile and old macadamia trees. In Australia, P. cinnamomi and P. multivora has been identified to cause severe stem canker in macadamia orchards. Currently, various varietal improvement research programs on macadamia are underway, not only to obtain high-yielding and precocious macadamia germplasm but to develop macadamia genotypes with acceptable levels of tolerance/resistance to pests and diseases. In this study, we selected macadamia genotypes for their acceptable levels of tolerance/resistance to Phytophthora infection, after screening about 360 macadamia genotypes against to P. cinnamomi and P. multivora, using a rapid detached leaf and plant inoculation assays. These macadamia plant materials were collected from a major macadamia arboretum in Queensland. Our results revealed segregation of macadamia genotypes into two spectrum of susceptible and tolerant macadamia genotypes. Hence, strong representatives within the tolerant and susceptible spectrum were further investigated in order to understand if the basis of the differential response is driven by a variation in structural, physiological or genetic markers, following a challenge with Phytophthora spp. Our result revealed a marked variation in structural response during the infection process, between the selected susceptible, ‘HAES816’ and tolerant germplasm and ‘HAES344’. This information will provide evidence to support potential preferential selection of tolerant macadamia genotypes potentially useful for breeding against Phytophthora diseases. Further studies will characterize tolerant macadamia progenies to develop marker-assisted selection protocols for resistance, and explore defense mechanisms response.
Keywords: proteacea; pathogen; tree nuts proteacea; pathogen; tree nuts
MDPI and ACS Style

Jeff-Ego, O.; Henderson, J.; Topp, B.; Drenth, A.; Akinsanmi, O. Variations in macadamia varietal susceptibility to Phytophthora multivora and P. cinnamomi. Proceedings 2019, 36, 109.

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