Tree Genetics & Genomes

, 15:24 | Cite as

Population structure, genetic diversity and linkage disequilibrium in a macadamia breeding population using SNP and silicoDArT markers

  • Katie O’ConnorEmail author
  • Andrzej Kilian
  • Ben Hayes
  • Craig Hardner
  • Catherine Nock
  • Abdul Baten
  • Mobashwer Alam
  • Bruce Topp
Original Article
Part of the following topical collections:
  1. Population structure


Macadamia (Macadamia integrifolia Maiden & Betche, Macadamia tetraphylla L.A.S. Johnson and their hybrids) is grown commercially around the world for its high-quality edible kernel. Traditional breeding efforts involve crossing varieties to produce thousands of progeny seedlings for evaluation. Cultivar improvement for nut yield using component traits and genomics are options for macadamia breeding, but accurate knowledge of genetic diversity and structure of the breeding population is required. This study reports allelic diversity within and between families of 295 seedling offspring from 29 parents, population structure and the extent of linkage disequilibrium (LD) in the population. Genotyping generated 19,527 silicoDArT and 5329 SNP markers, and, after filtering, 16,171 silicoDArTs and 4113 SNPs were used for diversity analyses. LD decay was initially rapid at short distances, but low-level LD persisted for long distances, with an average r2 = 0.124 for SNPs within 1 kb of each other. The seedling population was relatively genetically diverse and very similar to that of the 29 parents. The diversity (HE = 0.255 for progeny and 0.250 for parents) among these individuals indicates the level of diversity at the wider population level in the breeding programme, though the population appears less diverse than other fruit crops. Macadamia progeny was moderately differentiated (FST = 0.401) and formed k = 3 distinct clusters, which represents M. integrifolia germplasm separating from two different hybrid groups. There was low to no relationship between heterozygosity and performance for nut yield among progeny. These findings will inform future genomic studies of the Australian macadamia breeding programme, such as genome-wide association studies and genomic selection, where knowledge and control of population structure are vital.


Horticulture Plant breeding Progeny Genomics Diversity Arrays Technology 



This research has been funded by Hort Innovation, using the Macadamia research and development levy and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. KO thanks the Australian Postgraduate Award and Charles Morphett Peglar scholarship for financial support, macadamia orchard growers and managers, as well as the team at the Diversity Arrays Technology for their guidance. Thanks also to Dr. Mark Dieters, Dr. Jodi Neal, Dr. David Innes, Professor Robert Henry and Kirsty Langdon for their suggestions and comments.

Data archiving statement

The SNP and silicoDArT markers generated and analysed during the current study are obtainable from the University of Queensland’s Institutional Data Access/Ethics Committee, but restrictions apply to the availability of these data. The dataset “SNPs and silicoDArT markers of B1.2 progeny and parents” is available at for researchers who meet the criteria for access to confidential data. Contact

Compliance with ethical standards

Competing interests

Andrzej Kilian is employed by the Diversity Arrays Technology Pty Ltd. which provided genotyping services in this study, but this had no effect on the conclusions of this study.

Supplementary material

11295_2019_1331_MOESM1_ESM.docx (69 kb)
ESM 1 (DOCX 69 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Queensland Alliance for Agriculture and Food InnovationUniversity of QueenslandSt. LuciaAustralia
  2. 2.Diversity Arrays Technology Pty LtdUniversity of CanberraBruceAustralia
  3. 3.Southern Cross Plant ScienceSouthern Cross UniversityLismoreAustralia
  4. 4.AgResearch, Grasslands Research CentrePalmerston NorthNew Zealand

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