Molecular and agro-morphological variation in sorghum (Sorghum bicolor (L.) Moench) germplasm from Sudan and ICRISAT under drought stress condition

Low and erratic rainfall constitutes a major constraint to sorghum cultivation and impedes sorghum yield improvement in semi-arid climate zones. For estimating genetic and agro-morphological variability of sorghum under drought stress conditions, 40 sorghum genotypes were analysed with 16 simple sequence repeats (SSRs) and evaluated under natural drought condition across three environments. In total 98 polymorphic bands were detected with a mean of 6.1 alleles per SSR locus. By this approach each accession is uniquely fingerprinted. Genetic similarity estimates ranged from 0 to 0.88 with a mean of 0.32. The polymorphic information content (PIC) for SSRs ranged from 0.33 (SB34) to 0.86 (SB10). Diversity index for all accessions was 0.67. Within sub-groups, DI ranged from 0.47 (Mugud group) to 0.72 (Milo group). Mantel statistics revealed a good fit of the UPGMA cluster to the original genetic similarity data (r = 0.88). UPGMA clustering produced two main clusters comprising genebank accessions cluster and cultivars, landraces and synthetic cluster. Grouping of accessions by UPGMA cluster analysis matched with the pedigree information and morphological characters (Feterita, Mugud, and Milo types), indicating the strong differentiation among the sorghum materials. Significant differences were detected among the genotypes for all traits measured under stress condition, which included: days to flowering, plant height, grain yield/plant, growth rate, biomass, 1000-grain weight and harvest index. Based on the yield superiority under stress condition, relative yield, and days to 50 % flowering some genotypes could be selected to be grown under stress condition, and included as parents in breeding programs.