Molecular variability and salinity effects on growth characters and antioxidant enzymes activity in Egyptian barley genotypes

To evaluate the response of ten barley genotypes to high yield potency and constant performance under normal and saline soil conditions this study was carried out. All agronomic studied traits were significantly decreased due to saline stress. The main genotypic effect and genotype by environment interaction (GGE) biplot analysis revealed that Lines 6, 4, 8 and Giza-123 were the highest in the productivity and more tolerant to saline stress. Results of SSI indicated that, some genotypes were considered to be the highly tolerant for the studied traits. Also, the physiological response of barley leaves to salinity indicated that the activities of antioxidant defense enzymes were changed in equal with the increased salt concentrations in tolerant genotypes. Under gradual salt stress intensity, Lines 3, 5 and 6 showed highly increase in their peroxidase (POD), catalase (CAT) and polyphenol oxidase (POX) effectiveness associated with a significant altitude in their germination rate especially at 10 dsm(-1) of NaCl. All genotypes recorded a significant excess in their activities under mild salt stress concentration (10 dsm(-1) of NaCl) followed by a strong reduction in POD and CAT activities at sharp stress (14 dsm(-1) of NaCl). While POX activity showed higher increase at 14 dsm(-1) of NaCl as compared to 10 dsm(-1) of NaCl and control treatments. Molecular analysis showed that a total of 90 different loci with an average of 12.86 loci per RAPD primer were amplified from different barley genotypes in the three different systems, single, double and triple-RAPD, out of them, 77 loci (85.56%) were found to be polymorphic. The total percentages of polymorphism were decreased with increasing the number of primer combinations which recorded 91.67, 82.35 and 62.50% of polymorphism in the single, double and triple-RAPD systems, respectively, indicating that single-RAPD technique showed the highest percentage of polymorphism (91.67).