Introduction of Sesamum radiatum in green spaces: preliminary genetic study using HAT-RAPD

Background and aim: The promotion of indigenous floral diversity would have a positive impact on ecosystem services and provide a source of additional income for local residents. Sesamum radiatum (Pedaliaceae) has great potential because it can provide a wide range of ornamental, ethnobotanical and nutritional services. Genetic studies are advocated before the increased introduction of a species into green spaces. Therefore, we aimed to study genetic diversity and differentiation among both disjunct and geographically close populations of S. radiatum in Gabon and Cameroon, to better manage indigenous genetic resources. Methods: Thirteen autochthonous populations of S. radiatum from two disjunct savanna areas of southeastern Gabon and northern Cameroon, separated by rain forest, were analysed using a highly reproducible high annealing temperature-random amplified polymorphic (HAT-RAPD) protocol. Genetic differentiation was assessed using distance-based and Bayesian approaches. Results and conclusion: The observed values of genetic differentiation between populations varied considerably (FST 0.041 to 0.706), with the majority found in the very high genetic differentiation range. Only two major genetic clusters were identified, mostly coinciding with geographic sampling areas. One of the populations from Cameroon showed signs of admixture possibly due to more intense agricultural activities in the area. The genetic differentiation among geographically close populations in Gabon is weak and most likely due to indigenous anthropogenic activities in connection with the traditional use of S. radiatum. Thus, the production and dissemination of planting material used, for instance, for green space development should take place within the main clusters in order not to distort the existing genetic structure, while benefiting from sufficient genetic diversity within the regions themselves. Keywords: green spaces, indigenous species, genetic diversity, Sesamum radiatum