Local scale patterns of gene flow and genetic diversity in a crop–wild–weedy complex of sorghum (Sorghum bicolor (L.) Moench) under traditional agricultural field conditions in Kenya
Date
2017-01-24
Authors
Mutegi, E.
Sagnard, F.
Labuschagne, M.
Herselman, L.
Semagn, K.
Deu, M.
de Villiers, S.
Kanyenji, B. M.
Mwongera, C.N.
Traore, P.C.S.
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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. Our results 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.
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Keywords
Gene flow, Natural introgression, Hybridization, Genetic diversity, Sorghum bicolor, Traditional agro-ecosystem
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