Members of the Forest Molecular Genetics and Eucalyptus Pine Pathogen Interactions (FMG-EPPI) team at FABI conducted a field trip to Lochaber Farms in Mbombela, Mpumalanga, to analyse the Macadamia mapping population samples involving approximately 500 Macadamia trees. The trip was conducted from 10-12 November by Dr Mary Ranketse together with Dr Nomathemba Majola and Ms. Tsholofelo Modise. Assistance on the farm was provided by Mr Samkelo Sydney Zulu of Lochaber Farms.

This mapping population was made by crossing HAES 695 with HAES 791 and consists of two crosses that we planted in 2022 and 2023. The trees from the 2022 cross were unfortunately lost due to frost during the winter seasons, with only some 25 trees still surviving out of 138 initially planted. The trees from the 2023 cross are healthy and growing well, showing a variety of phenotypes due to the diversity present across the genomes, since both the parents are hybrids. The DNA from these samples will undergo low-coverage skim sequencing and genome imputation, with the aim of constructing genetic linkage maps for HAES 695 and HAES 791 for Dr Ranketse’s postdoctoral research project. Phenotypic traits of interest for breeding and macadamia improvement ,encompassing over 50 data points, are being collected on an ongoing basis. These phenotypic traits will be used to find genetic associations through quantitative trait loci (QTL) mapping on the genetic linkage maps.

The mapping population was made by Mr Duncan Macgregor, Mr Alwyn du Preez and the iBreed team at Lochaber Farms and further supported by Macadamia South Africa (SAMAC). This is a long-term project to develop genetic and genomic resources and tools that can be used for macadamia tree improvement though innovative breeding technologies.