Sweet sorghum is an excellent feedstock for ethanol production and is also used for food and livestock feed. Germplasm collection and characterization in sweet sorghum is a crucial step towards breeding and development of superior genotypes for various end-uses. In the present study, 13 Simple Sequence Repeat (SSR) markers were used for genotyping 175 Ethiopian sweet sorghum genotypes alongside 27 improved accessions from eastern and southern Africa. All the tested markers detected 159 alleles and a high degree of polymorphism information content (PIC) averaging 0.69. A comparison between Ethiopian and improved accessions revealed higher allele numbers (124) in Ethiopian than improved accessions (92 alleles). More than half (65 out of 124) of the alleles observed in the Ethiopian accessions were rare (<5%) and 64 were private (only present within Ethiopian accessions) while in the improved accessions, 41% and 38% of the alleles detected were rare and private respectively. Both weighted Neighbor Joining-based clustering and hierarchical clustering grouped the 202 accessions into three major clusters based on geographical origin. Ethiopian accessions from the north (north Wello and south Tigray) not only clustered separately from accessions from the west central and eastern Ethiopia, but were also distinct from most of the improved genotypes. Our results reveal an unexploited highly diverse sweet sorghum genetic resource from Ethiopia that can be included in the regional breeding programs in order to efficiently optimize productivity
