Salinity induced alteration in DNA methylation pattern, enzyme activity, nutrient uptake and H2O2 content in pepper (Capsicum annuum L.) cultivars

Salinity is a major environmental stress that induces epigenetic modifications and limits plant growth. However, little is known about the role of salinity on DNA methylation in pepper cultivars. Therefore, the current study was aimed to evaluate the effect of different salinity levels (control (0.7), 3.5 and 7 dS m(-1)) on DNA methylation patterns, enzyme activity, nutrient uptake, malondialdehyde (MDA) and hydrogen peroxide (H2O2) content in three pepper cultivars (Dolmalik, Carliston, and Maras), which are commonly consumed in Turkey. Salinity had a significant impact on DNA methylation patterns in pepper cultivars, and 7 dS m(-1) level of salinity increased DNA methylation ratio by 11.11%, 10.00% and 5.45% in Carliston, Dolmalik and Maras cultivars, respectively, compared to the control. Our data showed that salinity increased DNA full methylation ratio, H2O2, and MDA content in Dolmalik and Carliston cultivars, and this accompanied by a reduction in enzyme activity, dry weight, and the ratio of K+/Na+, Ca2+/Na+, and Mg2+/Na+. However, DNA demethylation occurred in Maras, and this coincided with an increase in enzyme activity and the ratio of K+/Na+, Ca2+/Na+, and Mg2+/Na+ compared to Carliston and Dolmalik. In conclusion, DNA demethylation helped Maras cultivar to possess the ability to tolerate salinity stress, whereas, in Carliston and Dolmalik cultivars, DNA full methylation was observed in their genome at a high ratio. Hence, they were identified as susceptible cultivars to salinity stress compared to Maras cultivar.