Most drought-induced DNA methylation changes switched to pre-stress state after re-irrigation in barley (Hordeum vulgare L.)cultivars

Drought is the most important factor limiting crop production in arid and semiarid regions of the world. Epigenetic changes including DNA methylation are involved in response to environmental stresses such as drought. In this study, the coupled restriction enzyme digestion-random amplification (CRED-RA)technique was used to evaluate the methylation patterns in leaf of two Iranian barley cultivars "Afzal and Sararood" and one European barley cultivar "Aiace" in four moisture stress regimes (irrigation at 100 percent, 75 percent, 50 percent and 25 percent of field capacity)in three stages including before the application of drought stress, 14 days after stress and 14 days after re-irrigation in three replications. The measured traits were relative water content, photochemical efficiency of photosystem II (Fv/Fm), transpiration rate, sub-stomatal CO2 concentration and leaf surface temperature. The highest methylation changes observed in all three cultivars were the conversion of full methylation to external cytosine methylation. The highest instability of genome pattern was observed in Aiace cultivar and in OPB-07 primer in irrigation at 25 percent of field capacity. Although most of the methylated and de-methylated fragments switched to prestress state after irrigation, there were few fragments that remained stable in the plant's genomic memory. Results showed significant changes in methylation pattern of all three barley cultivars in response to moisture stress.