Genetic Diversity of Sweet Sorghum (Sorghum bicolor L.) Genotypes Revealed by Simple Sequence Repeat (SSR) Markers

Sorghum (Sorghum bicolor L.) is an important C4 cereal crop valued for its adaptability to diverse environmental conditions and its multiple uses in food, feed, and bioenergy. Understanding the genetic diversity among sorghum germplasm in addressing global food security challenges, especially in Egypt, facing environmental stressors such as climate change, rising temperatures, and increasing drought occurrences. This study evaluated the genetic diversity of sorghum genotypes using simple sequence repeat (SSR) markers. Genomic DNA was extracted from 17 sorghum accessions from different countries (4 from Africa, 2 from Asia, and 11 from North America) and amplified using 20 polymorphic SSR primers. The resulting allelic data were used to estimate genetic diversity parameters, including the number of alleles, polymorphism information content (PIC), gene diversity, and genetic similarity. Phenotypic traits retrieved from the gene bank, and their association with the polymorphic alleles was examined using correlation analyses. A total of 232 polymorphic alleles were identified, with PIC values per marker ranging from 0.70 to 0.93 (average = 0.87), indicating high marker informativeness. The SSR markers successfully differentiated the sorghum genotypes and revealed substantial genetic variability, with distinct genetic clusters corresponding to their specific phenotypic feature. Although molecular and phenotypic classifications showed varying levels of agreement, the combined analyses provided an assessment of genetic relationships and diversity within the evaluated germplasm. These findings demonstrate the effectiveness of SSR markers for characterizing sorghum genetic resources and highlight the need to incorporate more phenotypic traits. Ultimately, a comprehensive phenotypic-genotypic assessment approach will significantly enhance parent selection, optimize breeding strategies, and improve germplasm conservation efforts aimed at developing sustainable, high-yielding, and climate-resilient sorghum cultivars.