Distribution of wild relatives of Saccharum species hybrids in sugarcane cultivation regions of South Africa

Abstract

Hybridisation may occur between crop plants and wild relatives if certain barriers to gene flow are crossed. Gene flow from crop species to indigenous wild relatives can threaten biodiversity. In assessing the risk of cultivating a genetically modified (GM) sugarcane plant, studies should be conducted prior to the approved release of the GM crop into the environment. The aim of this study was to determine which wild Andropogoneae are closely related to Saccharum and occur in the sugar production areas of KwaZulu-Natal, Mpumalanga and Limpopo. Such data is required for a spatial risk assessment and the most closely related taxa, with the highest potential for hybridization with Saccharum, were identified from a global phylogeny for the Poaceae. Sorghinae is the closest related subtribe to Saccharinae within the Andropogoneae, having diverged less than 7.3 million years ago. Ten species were selected for spatial analyses based on their presence in the sugar production region: four species in the Saccharinae and six in the Sorghinae. Herbarium distribution records of the selected Saccharum wild relatives were sourced from herbaria that house relevant collections from the eastern provinces. Localities of selected species were overlaid with the extent of sugar production regions to highlight areas where distributions overlap. Such areas pose a high risk for gene flow from a GM sugarcane crop to wild relatives