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

Sagnard, F and Deu, M and Dembele, D and Leblois, R and Toure, L and Diakite, M and Calatayud, C and Vaksmann, M and Bouchet, S and Mallé, Y and Togola, S and Traore, P C S (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. ISSN 0040-5752

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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

Item Type: Article
Divisions: UNSPECIFIED
CRP: UNSPECIFIED
Subjects: Mandate crops > Sorghum
Depositing User: Ms K Syamalamba
Date Deposited: 17 Jan 2013 08:01
Last Modified: 07 Feb 2014 05:14
URI: http://oar.icrisat.org/id/eprint/6433
Official URL: http://dx.doi.org/10.1007/s00122-011-1662-0
Projects: UNSPECIFIED
Funders: United States Agency for International Development
Acknowledgement: UNSPECIFIED
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