Inter simple sequence repeat markers to assess genetic variability of Mauritanian sorghum (Sorghum bicolor L.)

Studying the genetic variability of local Mauritanian sorghum accessions holds significant importance within the context of sorghum improvement and development programs. Hence, this study aimed to explore the genetic diversity of sorghum accessions collected from different regions of Mauritania. We examined 30 sorghum accessions representing four populations, namely Hodh el Chargui, Hodh el Gharbi, Assaba, and Guidimagha, employing five Inter-Simple Sequence Repeat (ISSR) markers, which yielded 101 informative bands. Our examination of these sorghum populations revealed moderate genetic diversity, as indicated by the percentage of polymorphic bands (PPB = 86.7-100%), Nei's genetic diversity (He = 0.11-0.21), and Shannon's information index (I = 0.17-0.32). To evaluate genetic variation both within and among populations, we conducted an Analysis of Molecular Variance (AMOVA). Additionally, we used unweighted neighbor-joining-based cluster analysis, principal components analysis (PCoA), and structure analysis to elucidate population clustering. The Polymorphic Information Content (PIC) ranged from 0.25 to 0.30, with an overall mean of 0.27. Our AMOVA results revealed that 81% of the total genetic variation was within populations, with 19% among populations, with percentage of the genetic differentiation coefficient (Gst = 0.183). Cluster analyses did not exhibit distinct groupings of the studied populations based on their geographical origins. This observation is likely due to substantial gene flow (Nm = 2.23) among populations. Among the four populations we studied, those from Hodh El Gharbi (He = 0.18, %P = 66.34) and the Assaba region (Het = 0.21, %P = 67.33%) displayed the highest genetic diversity. Consequently, these areas hold potential as hotspots for identifying high-performing genotypes suitable for sorghum breeding programs. Furthermore, they are of paramount importance for the development of effective germplasm conservation strategies.