Abstract:
Wild sorghums are extremely diverse phenotypically,geneticallyandgeographically.However,thereis
an apparent lack of knowledge on the genetic structure and
diversity of wild sorghum populations within and between
variouseco-geographicalregions.Thisisamajorobstacleto
both their effective conservation and potential use in
breeding programs.The objective of this study was to assess
the genetic diversity and structure of wild sorghum
populations across a range of eco-geographical conditions in
Kenya. Sixty-two wild sorghum populations collected from
the 4 main sorghum growing regions in Kenya were genotyped
using 18 simple sequence repeat markers. The study
showed that wild sorghum is highly variable with the Coast
region displaying the highest diversity. Analysis of molecular
variance showed a significant variance component
within and among wild sorghum populations within regions.
The genetic structure of wild sorghum populationsindicated
that gene flow is not restricted topopulations within the same
geographic region. A weak regional differentiation was
found among populations, reflecting human intervention in
shaping wild sorghum genetic structure through seed-mediated
gene flow. The sympatric occurrence of wild and cultivated
sorghums coupled with extensive seed-mediated
gene flow, suggests a potential crop-to-wild gene flow and
vice versa across the regions. Wild sorghum displayed a
mixed mating system. The wide range of estimated outcrossing
rates indicate that some environmental conditions
may exist where self-fertilisation is favoured while others
cross-pollination is more advantageous.