Project team: Prof Nigel Barker, Quenton Kritzinger and Lizo Masters
Tylosema comprises five currently recognised species endemic to sub-Saharan Africa. T.esculentum and T. fassoglense are found in southern Africa where they share the common name ‘marama’. This tuberous drought-tolerant legume produces highly nutritious seeds that have potential for producing products to support nutrition in Africa. However, the plant has not yet been domesticated, constraining the supply necessary to supply cottage or larger industries with raw material.
In South Africa Tylosema populations growing in the grassland have been identified as T. esculentum, a species largely found in the Kalahari Desert. However these Tylosema plants live in habitats that more closely resembles that of T. fassoglense, a widespread savannah plants, prompting questions on the evolutionary history of the grassland Tylosema and their relation to other Tylosema species. Theresearchers set out to determine the species limits of Tylosema sp. in southern Africa. This is an essential first step to any domestication efforts. Phylogenies were constructed using nuclear and chloroplast markers to determine if the South African Tylosema from the grassland is a distinct taxon.The results show that phylogeny species limits in Tylosema are largely unclear and that molecular data or barcoding is an insufficient means of delimiting species. The unknown Tylosema sp. on the dolomite reserves of South Africa cannotbe said to be a separate species or subspecies to T. esculentum in the Kalahari on the basis of molecular data.
In order to fully understand the evolutionary history of Tylosema we must explore and categorize, in detail, the full extent of morphological and genetic variability within and between species. The inherent variability among Tylosema sp. would render T. fassoglense, and possibly T. angolense, a species of interest alongside T. esculentum in domestication and breeding programs.