Identification of ISSR and RAPD markers linked to yield traits in bread wheat under normal and drought conditions

Genetic variability and identification of some molecular markers were studied in twenty promising lines of wheat using agronomic traits, ISSR (inter simple sequences repeats) and RAPD (random amplified polymorphic DNA) markers. Significant variation was evidenced in all agronomic traits. The lines proved to be superior to the check cultivar Sahel1 in yield and its component traits. Lines L2, L7 and L8 were the best in most yield component traits in both seasons. Moreover, Lines L2, L4, L5, L7 and L8 showed drought tolerance by which they displayed high performance in agronomic traits as well as a low drought susceptibility index. The percentage of polymorphism was 39.3% and 53.2% for ISSRs and RAPDs, respectively. UBC-881 belonged to penta-nucleotide repeat sequences (GGGTG) that produced the highest level of polymorphism, while UBC-846 belonged to di-nucleotide repeat sequences (CA) that produced the lowest level of polymorphism. Genetic similarities among wheat lines based on ISSR and RAPD markers ranged from 0.81 to 1.00 and from 0.86 to 0.98, respectively. There was a low average of PIC (polymorphism information content) values which were 0.10 (ISSR) and 0.15 (RAPD). The RAPD technique exhibited a higher marker index (MI = 0.69) compared to ISSR (MI = 0.43). There was insignificant correlation between ISSR and RAPD data (0.168, p > 0.05). There were two markers (UBC-881_450bp and OPF-10_540bp), on each of which two traits regressed significantly. The associated markers each explained a maximum regression of 18.92-34.95% of the total available variation for individual associated traits.