Genetic diversity analysis of sorghum (Sorghum bicolor L. Moench) landraces from northwestern Morocco using ISSR and AFLP markers

The objective of study aimed to analyze the genetic diversity and genetic structure of Moroccan landraces of sorghum (Sorghum bicolor L. Moench). Samples were obtained from 34 fields in the northern regions, specifically from Larache (13 fields), Tangier (11 fields), Chefchaouen (5 fields), and Tetouan (5 fields). A total of 398 individual plants were collected, including three accessions from each of the five cultivated races of sorghum (bicolor, durra, caudatum, guinea, and kafir) from the World Collection. Two molecular marker methods, inter-simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP), were employed. Four ISSR primers produced 185 reproducible bands, of which 177 (96%) exhibited polymorphism. Three AFLP primer combinations were used to detect 226 markers, out of which 198 (88%) were polymorphic. The average polymorphic information (PIC) values for ISSR and AFLP markers were calculated to be 0.98 and 0.97, respectively. Both markers revealed a higher relative genetic differentiation, with values of 0.5595 (ISSR) and 0.6216 (AFLP), while the gene flow (Nm) between fields was determined to be 0.3937 (ISSR) and 0.3043 (AFLP). Analysis of Molecular Variance (AMOVA) confirmed a greater variation within the field (57%). Classification of the Moroccan landraces based on Jaccard's similarity index led to the identification of two primary genetic pools, which was further supported by the unweighted pair group method with arithmetic mean (UPGMA) clustering and STRUCTURE analysis. The Mantel test revealed lack of correlation between genetic structure and microgeographical distribution. The ISSR and AFLP data suggest that the bicolor, durra, and caudatum races are more genetically related to the Moroccan landraces of sorghum than kafir and guinea.