GENETIC DIVERSITY AND RELATIONSHIPS AMONG SOME BARLEY GENOTYPES FOR NET BLOTCH DISEASE RESISTANCE USING RAPD, SCOT AND SSR MARKERS

Abstract

To evaluate the resistance of some barley genotypes for net blotch disease and grain yield and its related traits, twenty genotypes (12 local varieties and 8 exotic lines) of barley were used. Expression of severity to foliar infection varied between the evaluated genotypes, Giza 117 and Giza 2000 appeared the highest infection response, Giza 123, Giza 124, Giza 126 and Giza 131 were moderately susceptible, while the other genotypes ranged between resistant to moderately resistant. Line 81 and Line 91 proved to be most resistant genotypes for net blotch. Moreover, Giza 133 and line 91 showed superiority in grain yield values over all the tested barley genotypes and high resistance reaction for net blotch disease. Genetic variability and relationships among the used barley genotypes were evaluated by using five RAPD primers, three SCoT primers and eight SSR primer pairs. A high degree of polymorphism was detected with the three types of DNA markers which recorded 70.83, 77.42 and 72.5%, respectively. Alleles number ranged from 8 to 15, 9 to 12 and 2 to 8 per primer, with averages of 9.6, 10.33 and 5 per RAPD, SCoT and SSR primers, respectively. The highest percentage of genetic similarity as revealed by combined RAPD, SCoT and SSR data was found between line 81 and line 91 (90.7%), while the lowest similarity percentage was detected between Giza 124 and line 46 (65.2%). Giza 134 and Line 9 genotypes were resistant for net blotch disease while they gave positive genotype-specific markers with RAPD and SCoT analyses. Only Giza 123 genotype gave a positive genotype-specific marker using SSR analysis. Therefore, these genotype-specific markers could be considered as a molecular marker for net blotch disease response under similar conditions.