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Ongoing project

Genetic diversity and population structure of wild and domesticated macadamia (MC18004)

Key research provider: Southern Cross University

What’s it all about?

Beginning in the second half of 2019, this investment is uncovering information on the genetic history of macadamias that will ultimately assist in the development of new and improved varieties for growers. As wild populations of macadamia are found only in subtropical eastern Australia, this means they are an irreplaceable source of genetic material that could be used in the development of improved varieties.

The project team is tasked with analysing the biological data of a large collection of over 680 macadamia plant samples including wild and planted trees, predominant cultivars, new levy-funded cultivars and germplasm from Australian and Hawaiian breeding programs.

Key outcomes of the project include, but are not limited to:

  • Defining the distribution and structure of genetic diversity in wild, planted and domesticated germplasm to determine which populations and trees should be prioritised for conservation and included in future breeding collections.

  • Reconstructing the macadamia ‘family tree’ to confirm and discover interrelationships between different cultivars. This will help trace the history of macadamia domestication and contribute to a greater understanding of the species that can be used to inform future variety work.

  • Identifying the wild origins of macadamia domestication, including those of Australian cultivars and breeding program selections. This information will be crucial for identifying which populations and trees already have their genetics captured within cultivars and breeding programs, and also which novel genotypes and phenotypes are underrepresented in domestic germplasm that may have the potential to drive future productivity.

Since commencement of the project, an extensive collection of macadamia leaf samples and DNA, including wild and planted trees of all macadamia species and cultivated varieties, have been maintained at Southern Cross University.

The team completed sample collection following field trips to M. ternifolia sites and Hidden Valley Plantations in Queensland. Laboratory work was finalised, and genotype data was collected for over 1000 accessions.

Preliminary analysis of 79 macadamia cultivars supports previous genetic evidence that most Hawaiian cultivars are closely related and derived from a single Macadamia integrifolia origin. ‘Eggshell’ and ‘Probert 2’ are pure M. tetraphylla while many Australian, South African, Chinese and Guatemalan cultivars are hybrids with M. tetraphylla content. HAES 791 was the only cultivar with significant (25%) M. ternifolia content.

Related levy funds

This project is a strategic levy investment in the Hort Innovation Macadamia Fund