Genotype-specific patterns of physiological and antioxidative responses in barley under salinity stress

Using reliable salt tolerance markers is a key component in barley breeding programs. In this study, physiological and antioxidative markers of two Tunisian barley salinity tolerance contrasting genotypes Boulifa (B) and Manzel Habib (MH) were assessed at 0, 3, 6 and 9 days of 200 mM salt treatment. Salinity caused decrease in growth, degraded photosynthetic activity and reduced water-holding capacity in both genotypes with more pronounced negative effects in the salt-sensitive (MH) compared to the salt-tolerant (B) genotype. On the other hand, the lower oxidative damage in B compared to MH under salt stress could be explained by higher activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX) and glutathione reductase (GR). Additionally, a genotype-specific pattern of enzyme activity and corresponding gene expression was revealed in the two barleys under salt stress. In this context, a positive correlation was noted for the SOD. On the other hand, multivariate analysis marked SOD and APX as the most discriminating factors between both stressed genotypes. Our findings could be considered for selection in breeding programs for salt stress tolerance in barley.

Automated summary

Using reliable salt tolerance markers is important in barley breeding programs. This study examined the physiological and antioxidative markers of two Tunisian barley genotypes under salt stress. The results showed that salinity caused decreased growth and damaged photosynthetic activity in both genotypes, with more pronounced effects in the salt-sensitive genotype. However, the salt-tolerant genotype exhibited lower oxidative damage, which could be attributed to higher antioxidant enzyme activities. Additionally, a genotype-specific pattern of enzyme activity and gene expression was observed under salt stress.