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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #284469
Title: 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

Author
item Cuevas, Hugo
item Prom, Louis

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2013
Publication Date: 6/1/2013
Citation: Cuevas, H.E., Prom, L.K. 2013. 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. Genetic Resources and Crop Evolution. 60(6):1817-1830.

Interpretive Summary: The genetic diversity and population structure present in the Ethiopian sorghum collection maintained at the USDA-ARS National Plant Germplasm System (NPGS) has not been studied. Therefore, 137 Ethiopian accessions from NPGS were randomly selected and characterized with 20 strategically selected SSR markers. Population structure analysis indentified two subpopulations of 77 and 41 accessions, respectively, while a third group was comprised by 19 accessions whose classifications were not defined (i.e. hybrids). Results showed that the genetic diversity present in Ethiopian germplasm is the highest when compared to collections from other countries. The genetic information presented herein is valuable to conservation programs and promotes the use of Ethiopian germplasm for sorghum breeding programs.

Technical Abstract: The genetic 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 SSR 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 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. In fact, effective population size of this random sample was estimated at 134 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.