Genetic variation in Haworthia pumila and H. herbacea

Horizontal starch gel electrophoresis was used to examine genetic diversity within and differences between one population each of two morphologically different species of Haworthia, namely H. pumila and H. herbacea. Twenty-five leaf samples of each species were surveyed for 24 proteins of which 13 were useful for routine analysis, and gene products of 16 protein coding loci revealed genetic variation at 7 (43.8%) thereof in both species. Values of 1.63 (± 0.20) and 1.56 (± 0.18) were obtained for the mean number of alleles per locus and the average heterozygosity per locus was calculated at 0.168 (± 0.058) and 0.144 (± 0.048) for H. herbacea and H. pumila respectively. The malate dehydrogenase-2 locus is a potential genetic marker to identify the species studied electrophoretically. The mean genotypic distance index between the populations studied was 0.184, an indication of large degree of differentiation between the species. These values are much higher than values obtained for other members of the Aloaceae, showing that normal levels of genetic variation can be expected in at least some succulent monocotyledons.