RAPD variation within and between natural populations of morama [Tylosema esculentum (Burchell) Schreiber] in southern Africa

RAPD markers were used to investigate genetic variation in natural populations of morama [Tylosema esculentum (Burchell) Schreiber]. This species is a wild, perennial, outbreeding legume indigenous to the Kalahari Desert region of southern Africa. Morama seed has a high protein content and has traditionaliy been an important wild source of food for the people of this region. It is considered to have great potential for development as a new crop for the semi-arid tropics. Investigation of genetic diversity is a prerequisite for the genetic improvement of any species and this is the first such investigation in morama. Considerable RAPD variability was detected in each of the three morama populations sampled. Most of this variation (85%) occured within, rather than between, populations in agreement with other studies involving outbreeding perennial species. This suggests that sufficient genetic variation for breeding purposes may be found by sampling 30–40 plants from only one or two populations. There were significant differences in the frequency of RAPD loci between populations but no population-specific RAPD markers were found. Although there was no clear evidence of population differentiation between the morama populations, more intensive sampling may reveal details of within-population genetic structure in these populations. This analysis confirms the usefulness of RAPD markers for investigation of genetic variation in natural populations and the technique is fast and provides numerous polymorphic markers