Abstract:
Little information is available on the extent and
patterns of gene flow and genetic diversity between cultivated
sorghum and its wild related taxa under local agricultural
conditions in Africa.As well as expanding knowledge on the
evolutionary and domestication processes for sorghum,such
information also has importance in biosafety, conservation
and breeding programmes. Here,we examined the magnitude
and dynamics of crop–wild gene flow and genetic variability
in a crop–wild–weedy complex of sorghum under traditional
farming in Meru South district, Kenya. We genotyped 110
cultivated sorghum,and 373 wild sorghum individuals using a
panel of ten polymorphic microsatellite loci. We combined
traditional measures of genetic diversity and differentiation
with admixture analysis,population assignment,and analyses
of spatial genetic structure to assess the extent and patterns of
geneflow and diversity between cultivated and wild sorghum.
Ou rresults indicate that geneflow is asymmetric with higher
rates from crop to wild forms than viceversa. Surprisingly,our
data suggests that the two congeners have retained substantial
genetic distinctness in the face of geneflow. Nevertheless,we
found no significant differences in genetic diversity measures
between them. Our study also did not find evidence of isolation by distance in cultivated or wild sorghum,which suggests
that gene dispersal in the two con specifics is not limited by
geographic distance. Overall our study highlights likely
escape and dispersal of transgenes within the sorghum crop–
wild–weedy complex if genetically engineered varieties were
to be introduced in Africa’s traditional farming systems.
