Progress made with molecular markers for genetic improvement of macadamia

Macadamias are cultivated for their edible kernel. The early industry was based on the species M integrifolia, M. tetraphylla and their hybrids. The majority of early selections were undertaken in Hawaii from a suspected limited gene pool. Over the years, other selections have been made and taken up by the industry. The next phase of macadamia improvement will involve quantitative breeding aided by molecular techniques. Currently, the ability to assess the genetic relatedness using the isozyme technology is limited to only a few cultivars since several isozyme alleles are shared by most of the commercial cultivars. To overcome this problem, molecular markers through Random Amplified Polymorphic DNA (RAPD) and Sequence Tagged Sites (STSs) were developed. Results show that these markers follow Mendelian inheritance. These markers have been used to assay genetic diversity of 76 individuals with known backgrounds and the results indicate that they can be effectively used on macadamia. Currently, we are expanding this work to include authentication of cultivars and to seek associations between genetic distance and specific combining ability of different cultivars which will assist us in the planning of new crosses.