Genetic diversity, structure, gene flow and evolutionary relationships within the Sorghum bicolor wild-weedy-crop complex in a western African region

Sagnard Fabrice, Deu Monique, Dembele Dékoro, Leblois Raphaël, Touré Lassana, Diakite Mohamed, Calatayud Caroline, Vaksmann Michel, Bouchet Sophie, Mallé Yaya, Togola Sabine, Traoré Pierre Sibiry. 2011. Genetic diversity, structure, gene flow and evolutionary relationships within the Sorghum bicolor wild-weedy-crop complex in a western African region. Theoretical and Applied Genetics, 123 (7) : pp. 1231-1246.

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Quartile : Outlier, Sujet : HORTICULTURE / Quartile : Q1, Sujet : AGRONOMY / Quartile : Q1, Sujet : PLANT SCIENCES / Quartile : Q2, Sujet : GENETICS & HEREDITY

Abstract : Gene flow between domesticated plants and their wild relatives is one of the major evolutionary processes acting to shape their structure of genetic diversity. Earlier literature, in the 1970s, reported on the interfertility and the sympatry of wild, weedy and cultivated sorghum belonging to the species Sorghum bicolor in most regions of sub-Saharan Africa. However, only a few recent surveys have addressed the geographical and ecological distribution of sorghum wild relatives and their genetic structure. These features are poorly documented, especially in western Africa, a centre of diversity for this crop. We report here on an exhaustive in situ collection of wild, weedy and cultivated sorghum assembled in Mali and in Guinea. The extent and pattern of genetic diversity were assessed with 15 SSRs within the cultivated pool (455 accessions), the wild pool (91 wild and weedy forms) and between them. F ST and R ST statistics, distance-based trees, Bayesian clustering methods, as well as isolation by distance models, were used to infer evolutionary relationships within the wild-weedy-crop complex. Firstly, our analyses highlighted a strong racial structure of genetic diversity within cultivated sorghum (F ST = 0.40). Secondly, clustering analyses highlighted the introgressed nature of most of the wild and weedy sorghum and grouped them into two eco-geographical groups. Such closeness between wild and crop sorghum could be the result of both sorghum's domestication history and preferential post-domestication crop-to-wild gene flow enhanced by farmers' practices. Finally, isolation by distance analyses showed strong spatial genetic structure within each pool, due to spatially limited dispersal, and suggested consequent gene flow between the wild and the crop pools, also supported by R ST analyses. Our findings thus revealed important features for the collection, conservation and biosafety of domesticated and wild sorghum in their centre of diversity. (Résumé d'auteur)

Mots-clés Agrovoc : Sorghum bicolor, Variation génétique, Collection de matériel génétique, Flux de gènes, Génétique, Plante sauvage, Mauvaise herbe, Plante de culture

Mots-clés géographiques Agrovoc : Guinée, Mali

Classification Agris : F30 - Plant genetics and breeding
F70 - Plant taxonomy and geography

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations

  • Sagnard Fabrice
  • Deu Monique, CIRAD-BIOS-UMR AGAP (FRA)
  • Dembele Dékoro, ICRISAT (MLI)
  • Leblois Raphaël, INRA (FRA)
  • Touré Lassana, IER (MLI)
  • Diakite Mohamed, IRAG (GIN)
  • Calatayud Caroline, CIRAD-BIOS-UMR AGAP (FRA)
  • Vaksmann Michel, CIRAD-BIOS-UMR AGAP (MLI) ORCID: 0000-0002-5258-1279
  • Bouchet Sophie
  • Mallé Yaya, ICRISAT (MLI)
  • Togola Sabine, ICRISAT (MLI)
  • Traoré Pierre Sibiry, ICRISAT (MLI)

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