Genomics of Macadamia, a Recently Domesticated Tree Nut Crop

Abstract

The tree nut crop known as macadamia includes two cultivated species that readily hybridize. This Australian native from subtropical rainforests was domesticated recently, and cultivated trees are very few generations from their wild progenitors. A genomic understanding of the crop has the potential to deliver massive genetic improvements to a worldwide industry, and reveal the genetic changes that have occurred through the domestication process. The bulk of research efforts in this field have focused on the development of molecular marker technology and its various applications in assessing both cultivated and wild germplasm. Markers were also used as the basis of genetic linkage mapping for macadamia's chromosomes , but regions controlling important traits have not yet been localized. Gene sequence information for macadamia is very limited, although two genes encoding proteins with antimicrobial properties have been described. Macadamia is the most economically valuable member of the ancient Proteaceae family, and has few cultivated relatives. This crop is the obvious target within the family for developing further genomics resources. Comparing the structure of the macadamia genome and its functional components with those of crops from other plant families, particularly nut, fruit, and tree species, should provide insights for understanding the evolution and genomic regulation of many important biological and agronomic traits.