Experimental study of gene flow between wild and cultivated Pennisetum glaucum

Abstract : Under natural conditions wild and cultivated pearl millet, Pennisetum glaucum, exchanged genes for millenia and, nevertheless, maintain high morphological differentiation. Under experimental conditions in the Sahel, hybridization between wild and cultivated pearl millet was measured using isozymic markers and interpreted in relation to the phenology of the plants. Gene flows were assymmetric, engendering 8% of hybrids in the progeny of the wild phenotype, 45% in that of the cultivated phenotype, and 39% in that of the intermediate " shibra " phenotype; these last two phenotypes constitute the sample of cultivated pearl millet. The proportion of hybrids in the progeny of the wild sample was time-dependent during the flowering phase of cultivated pearl millet. The proportion of hybrids produced by the cultivated pearl millet was not time-dependent. In the seeds produced by the cultivated phenotype along its reproductive phase, the proportion of viable seeds was negatively correlated to the frequency of hybrids. Likewise, the speed of germination of seeds produced by the cultivated or the "shibra" phenotypes was negatively correlated to the frequency of the hybrids that they contained. The effects of balancing among genetic intermixing, isolation and reproduction barriers, differential anthropic and natural selection pressures, are discussed in order to better understand the evolution and the maintenance of the polymorphism of Pennisetum glaucum.
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Jean-François Renno, Thierry Winkel, F. Bonnefous, Gilles Bezançon. Experimental study of gene flow between wild and cultivated Pennisetum glaucum. Canadian Journal of Botany, National Research Council Canada, 1997, 75 (6), pp.925-931. ⟨10.1139/cjb-75-6-925⟩. ⟨ird-00142387⟩

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