Genetic Diversity and Mating System of Wild Sorghum in Kenya and Adaptive Value of Wild x Cultivated Sorghum Hybrids

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In Kenya cultivated and wild sorghums grow sympatrically, hence concerns about crop-towild gene flow are understandable. The crop-to-wild gene flow rates are unknown, as are the adaptive values of crop alleles in wild populations. The major concern is that genes added to crops through modern breeding, such as insect resistance or herbicide tolerance, might spread to wild or weedy relatives creating a “super weed” that is either difficult to control or detrimental to the environment. Furthermore, information is lacking on how the genetic diversity of wild sorghum populations is influenced by gene flow from cultivated sorghum. In addition, the crossing barriers between cultivated sorghum and its wild relatives and the level of genetic diversity of wild sorghums in Kenya have not been documented. Information on the relative extent of the diversity pattern within and among genetically defined groups of distinct eco-systems is lacking. Use of male-sterile bait plants in field trials to estimate gene flow has been questioned due to lack of competing pollen. Moreover, the wild sorghum mating system is not well understood and no information exists on competition between a plant’s own and alien pollen.