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Genetic parameters of husk spot resistance in macadamia breeding families

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Nunn, J., Hardner, C., De Faveri, J., Akinsanmi, O. A., O'Connor, K. M., Alam, M. and Topp, B. (2023) Genetic parameters of husk spot resistance in macadamia breeding families. Euphytica, 219 (5). p. 54. ISSN 1573-5060


Article Link: https://doi.org/10.1007/s10681-023-03169-2


Husk spot caused by the Pseudocercospora macadamiae fungus induces premature abscission of fruit in many industry standard macadamia cultivars. Fungicides and other management strategies add to farm costs, thus breeding for varietal resistance is important. Genetic parameters of husk spot symptom expression had not previously been estimated. To guide selection methods for field resistance, over 300 open-pollinated seedlings of 32 families and 24 parent genotypes were inoculated, and seven symptom expression traits were evaluated. Narrow-sense and broad-sense heritabilities were estimated, breeding values were predicted, and correlations between breeding values of trait pairs were tested for significance. The traits with the highest heritabilities were necrotic lesion number per fruit (H2 = 0.41–0.59; h2 = 0.21–0.30) and necrotic incidence (H2 = 0.19–0.27; h2 = 0.17–0.24). Breeding values of the two traits were highly correlated (r = 0.98; p < 0.001), suggesting that either trait could be used to indirectly select for the other. All genotypes expressed symptoms to some degree, however, breeding values for necrotic traits and symptom-induced premature abscission were low for clones and progeny of cultivar ‘HAES791’. Necrotic trait breeding values were also promising for progeny of cultivar ‘HAES246’ and clones of Australian Macadamia Breeding Program elite selection, ‘BAM263’. Having been identified as potentially partially resistant, these selections can now be further evaluated and used as parents of new progeny populations.

Item Type:Article
Corporate Creators:Department of Agriculture and Fisheries, Queensland
Business groups:Horticulture and Forestry Science
Keywords:Macadamia Husk spot Pseudocercospora macadamiae Fruit tree breeding Disease resistance
Subjects:Science > Botany > Genetics
Plant culture > Tree crops
Plant culture > Food crops
Plant culture > Fruit and fruit culture > Nuts
Plant pests and diseases
Live Archive:22 Jun 2023 04:35
Last Modified:19 Jan 2024 00:27

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