Genetic diversity among Sorghum bicolor L. Moench genotypes as revealed by prolamines and SSR markers

Sorghum (Sorghum bicolor L. Moench) is a leading cereal in the arid and semi-arid regions and ranks fifth in importance among the world’s grain crops. Given its importance as a staple food crop, a livestock feed crop and potentially a bioenergy crop, there is a constant need for its genetic improvement and an important step in this regard is the evaluation of genetic diversity in sorghum. In this study, 23 genotypes, including both local and exotic cultivars, were analyzed based on their water-soluble protein and prolamine-protein profiles. DNA-variation was investigated using twenty microsatellite, or simple sequence repeat (SSR) markers. There were no differences in the banding patterns of water-soluble proteins, indicating that it is highly conserved among the genotypes. The prolamine profiles showed differences in their banding patterns among the genotypes. Microsatellites detected a higher degree of genetic variation among the sorghum genotypes compared to the prolamines. All the 20 SSR loci were polymorphic with a total of 94 alleles. The number of alleles per locus ranged from 2 to 8, with an average of 4.7. A genetic diversity index (DI) of 0.63 was consistent with the reports of previous publications. This low DI might be due to the lower number of genotypes used in the study, most of which were from the United States. Our results indicate that the genotypes grouped according to their geographical origins. New alleles were detected for some microsatellite loci. This is important especially if a particular locus evaluated in this study is linked to a desirable trait, the data can be used for the identification of the progeny carrying those characteristics. This would further help in the identification of appropriate parental lines for an efficient plant-breeding program and in the conservation and utilization of genetic resources.