Poster Presentation International Plant Molecular Biology Conference 2024

Developing an Indirect selection strategy for nut borer and fruit spotting bug resistance in macadamia (#54)

Shelley Gage 1
  1. QAAFI, University of Queensland, Brisbane, QLD, Australia

The increasing global demand for macadamia products has led to increased plantings in Australia from 17000ha in 2009 to 38000ha in 2022. Losses in macadamia production caused by macadamia nut borer and fruit spotting bug are exhibited by abscission of the immature nuts and kernel damage. These losses have been measured at more than 38% of the crop. Previous studies showed that nut husk and shell thickness and hardness determine the level of resistance to these pests. The aim of this project is to develop an indirect marker assisted selection tool for pest resistance in macadamia. To confirm the association of nut traits with insect resistance, 24 cultivars with known shell hardness and thicknesses are being assessed for resistance to fruit spotting bug. Cages containing the insects have been placed over racemes of each tree. Nut traits and the level of damage are being measured. To investigate the association of nut traits under natural insect infestation, another study was carried out on 100 macadamia accessions.  Results from trait association and marker discovery will facilitate the use of nut genomics for the indirect selection of insect resistance in macadamia. Marker collation study will be used to validate this hypothesis. This genomic assisted selection for insect resistance in macadamia will improve the outcome for the plantation, as currently, phenologic selection can be done only once the trees have reached bearing age. This strategy would reduce the time and expense of spraying and improve economic and environmental outcomes.