Genetic Diversity and Population Structure Analysis of Ethiopian Sorghum [Sorghum bicolor (L.) Moench] Landraces Using Simple Sequence Repeat (SSR) Markers

Abstract

As developing effective conservation and management strategies relies on the genetic diversity of Sorghum, the study especially in a country like Ethiopia, which is the center of origin with a wide range of cultivation, is vital. Therefore, the present study has targeted to assess the genetic diversity and population structure of Sorghum [Sorghum bicolor (L.) Moench] landraces using simple sequence repeat (SSR) markers. Seventy-seven sorghum landraces representing five regions and ten populations were analyzed using 11 SSR markers. The analysis of diversity indices identifies a total of 49 alleles with an average of 4.5 alleles per locus. Different diversity parameters were computed, and the average Shannon’s diversity index and expected heterozygosity of the 11 loci were 0.61 and 0.36, respectively. The polymorphic information content (PIC) of the loci ranged from 0.23 to 0.67 with an overall mean of 0.48. The study revealed high gene diversity within the populations ranging from 0.25 to 0.72 with an overall mean of 0.53. The genetic distance and differentiation between possible pairs of regions and populations were low to moderate. Hierarchical AMOVA revealed that 82% and 79% of the total variation accounted for variation within regions and populations, respectively, leaving only 18% and 21% variations among regions and populations, respectively. The unweighted Neighbour-Joining based clustering, PCoA, and population structure analysis failed to group landraces according to their collection region and population, indicating the presence of high gene flow (Nm =1.16 or 0.95) between regions and population, respectively. Structure analysis confirmed two sub-groups with a greater degree of genetic admixture for both regions and populations. Overall, the genetic markers used were highly informative and useful tools to uncover the genetic structure of sorghum. The study also revealed the presence of high genetic diversity in Ethiopian sorghum landraces, indicating the potential to improve through breeding, and the need to design appropriate management strategies to maintain the available genetic resources.