Assessment of molecular diversity and population structure of the Ethiopian sorghum [ Sorghum bicolor (L.) Moench] germp
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RESEARCH ARTICLE
Assessment of molecular diversity and population structure of the Ethiopian sorghum [Sorghum bicolor (L.) Moench] germplasm collection maintained by the USDA–ARS National Plant Germplasm System using SSR markers Hugo E. Cuevas • Louis K. Prom
Received: 3 August 2012 / Accepted: 7 January 2013 / Published online: 11 February 2013 Ó Springer Science+Business Media Dordrecht (outside the USA) 2013
Abstract The molecular diversity and population structure present in the Ethiopian sorghum collection maintained at the USDA–ARS National Plant Germplasm System (NPGS) has not been studied. In addition, 83 % of the accessions in the Ethiopian collection lack passport information which has constrained their evaluation and utility. Therefore, 137 Ethiopian accessions from NPGS were randomly selected and characterized with 20 strategically selected simple sequence repeat markers. These markers indentified 289 alleles with average polymorphic information content of 0.78. The allele frequency distribution reflects that 62 % of the alleles were rare (\0.05), 17 % range from 0.05 to 0.10, and 22 % were higher than 0.10. Expected and observed heterozygosity were estimated at 0.78 and 0.23, respectively, demonstrating Ethiopia has high sorghum genetic diversity germplasm. Population structure analysis
Electronic supplementary material The online version of this article (doi:10.1007/s10722-013-9956-5) contains supplementary material, which is available to authorized users. H. E. Cuevas (&) USDA, Agricultural Research Service, Tropical Agriculture Research Station, 2200 P.A. Campos Ave. Ste 201, Mayaguez, PR 00680-5470, USA e-mail: [email protected] L. K. Prom USDA, Agricultural Research Service, Southern Plains Agriculture Research Center, 2765 F and B Road, College Station, TX 77845, USA
indentified two subpopulations of 77 and 41 accessions, respectively, while a third group was constituted by 19 accessions whose classifications were not defined (i.e. hybrids). Analysis of molecular variances determined variation within subpopulations as the major source of variation. Likewise, genetic differentiation between subpopulations was moderate (Fst = 0.10). These results indicated that a continuous exchange of genes between subpopulations of sorghum exists in Ethiopia. The absence of a well defined population structure positioned this germplasm as an important resource for the study and dissection of agricultural traits by association mapping. However, genetic redundancy analysis indicated the presence of highly related accessions, therefore, strategic selected accessions must be consider prior to phenotype evaluation of larger number of accessions. The Ethiopian collection is composed of highly genetically diverse germplasm, and the genetic information presented herein is valuable to ex situ and in situ conservation programs to promote the use of this germplasm for breeding programs. Keywords Ethiopia Genetic diversity Genetic redundancy Population structure Sorghum bicolor
Introduction Sorghum [Sorghum
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