Theoretical and Applied Genetics

, 123:1231

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

Authors

  • Fabrice Sagnard
    • CIRAD, UMR AGAP
    • ICRISAT, co/ILRI
    • CIRAD, UMR AGAP
  • Dékoro Dembélé
    • ICRISAT, Station de Samanko
  • Raphaël Leblois
    • INRA, UMR CBGP (INRA-IRD-CIRAD-Montpellier SupAgro)
  • Lassana Touré
    • IER-Sotuba
  • Mohamed Diakité
    • IRAG, CRA Bordo- Programme Céréales
  • Caroline Calatayud
    • CIRAD, UMR AGAP
  • Michel Vaksmann
    • CIRAD, UMR AGAP
    • IER-Sotuba
  • Sophie Bouchet
    • CIRAD, UMR AGAP
  • Yaya Mallé
    • ICRISAT, Station de Samanko
  • Sabine Togola
    • ICRISAT, Station de Samanko
  • Pierre C. Sibiry Traoré
    • ICRISAT, Station de Samanko
Original Paper

DOI: 10.1007/s00122-011-1662-0

Cite this article as:
Sagnard, F., Deu, M., Dembélé, D. et al. Theor Appl Genet (2011) 123: 1231. doi:10.1007/s00122-011-1662-0

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. FST and RST 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 (FST = 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 RST analyses. Our findings thus revealed important features for the collection, conservation and biosafety of domesticated and wild sorghum in their centre of diversity.

Supplementary material

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Supplementary Electronic File 1 (PDF 6 kb)
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Supplementary Electronic File 6 (PDF 8 kb)

Copyright information

© Springer-Verlag 2011