Genetic Diversity of Osteospermum Genotypes Analysed by AFLP and Chloroplast SSR Markers

Osteospermum cv. belongs to the so called 'New ornamental plants', which gained much popularity over the last few years. A collection of 111 Osteospermum and nine Dimorphotheca genotypes were evaluated by AFLP (Amplified Fragment Length Polymorphism) analysis. In the present study we analysed the genetic diversity within breeding pools from different breeders together with a selection of wild species. The genotypes could be grouped into four main clusters. While FACCIOLI et al. (2000) were able to classify the genotypes by origin of the cultivar, no such relation was found in the present work. Yellow flower colour, assumed to originate from only a few genetic sources was found in all four major clusters. However, within the clusters these genotypes were grouped together. Overall genetic distances among Osteospermum genotypes turned out to be small emphasizing the need to optimise the choice of parental genotypes in breeding programs aiming at low inbreeding depression. Three different cluster methods (UPGMA, Fitch and Margoliash and Neighbour-joining) were used to calculate the phenograms. To estimate the reliability of dendrograms a bootstrap-analysis has been carried out with 100 replicates. The phenograms revealed only marginal differences between the methods. These differences are mainly found for groups with small bootstrap-values, including interspecific hybrids. In addition to cluster analyses, the data set was analysed by principal component analysis (PCA) to display similarities among genotypes. The same four major groups could be distinguished supporting the cluster analyses. The AFLP data are complemented with data from two chloroplast SSR markers which allows the differentiation of eight cytoplasmic lineages among the genotypes investigated.