1. Genetics Department, Stellenbosch University, Private Bag X1, Matieland 7601, South Africa (nfvburger@sun.ac.za; ambo@sun.ac.za)
2. Genetics Department, University of Pretoria, Hillcrest, Pretoria, South Africa
3. Department of Botany and Plant Biotechnology, University of Johannesburg, Auckland Park, Johannesburg, South Africa (eduardv@uj.ac.za)