Submitted to: Tropical Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2008
Publication Date: 6/18/2008
Citation: Dida, M., Wanyera, N., Harrison Dunn, M.L., Bennetzen, J., Devos, K. 2008. Population Structure and Diversity in Finger Millet (Eleusine coracana) Germplasm.. Tropical Plant Biology 1: 131-141.
Interpretive Summary: Finger millet is a traditional crop grown predominately in East Africa and Southern India. It is believed to have originated in Ethiopia around 3000 B.C., late to have been domesticated in this region and transported eventually via sea trade to India in 1000 B.C. In the present study, 79 accessions of finger millet from 11 African and 5 Asian countries were subjected to DNA analysis. Results of this analysis support the movement of finger millet from Africa to India and the distinctiveness of subpopulation. Morphological analysis of the accessions also supports the distinctiveness between African and India subpopulations through observed differences in plant architecture and yield. DNA analysis further indicates that even though the populations are distinct, crosses between the subpopulations can occur naturally. This information sheds light on the genetics of finger millet and better equips plant breeders with the knowledge needed to carry out efficient breeding strategies for this important agrinomic crop.
Technical Abstract: A genotypic analysis of 79 finger millet accessions (E. coracana subsp. coracana) from 11 African and 5 Asian countries, plus 14 wild E. coracana subsp. africana lines collected in Uganda and Kenya was conducted with 45 SSR markers distributed across the finger millet genome. Phylogenetic and population structure analysis showed that the E. coracana germplasm formed three largely distinct subpopulations, representing subsp. africana, subsp. coracana originating from Africa and subsp. coracana originating from Asia. A few lines showed admixture between the African and Asian cultivated germplasm pools and were the result of either targeted or accidential intercrossing. Evidence of gene flow was also seen between the African wild and cultivated subpopulations, indicating that hybridizations among subspecies occur naturally where both species are sympatric. The genotyping, combined with phenotypic and population structure analyses proved to be very powerful in predicting the origin of breeding materials. The genotypic study was complimented by a phenotypic evaluation. The wild and cultivated accessions differed by a range of domestication-related characters, such as tiller number, plant height, peduncle length, seed color, and grain yield. Significant differences in plant architecture and yield were also identified between the Asian and African subpopulations. The observed population structure within cultivated finger millet is consistent with the theory that, after the introduction of finger millet from African into India via the trade routes some 3000 years ago, the two germplasm pools remain largely isolated until recent times. The significantly lower diversity present within the Asian subpopulation also suggest that it arose from a relatively small number of founder plants.