Evaluation of salinity tolerance of Egyptian barley genotypes and their dehydrin 6-based single nucleotide polymorphisms (SNPs) diversity

In many countries, freshwater sources for agricultural irrigation are scarce, making it challenging to meet the food production needs of the growing human population. Utilizing seawater for agriculture could be a potential solution for limited water resources. A lysimeter experiments evaluated fifteen barley genotypes irrigated with different levels of diluted seawater (S1 = 4.0, S2 = 8.0, and S3 = 12.0 dSm^-1). Morpho-physiological traits and exploring single nucleotide polymorphism (SNP) diversity among the most tolerant and sensitive genotypes during the winter seasons (2019/2020 and 2020/2021) were examined. Irrigation with diluted seawater at ECw 12.0 dSm^-1 significantly decreased leaf area index (by 35.54 %), total chlorophyll content (by 18.97 %), chlorophyll fluorescence (by 46.36 %), plant height (by 29.17 %), number of tillers per square meter (by 43.73 %), number of grains per spike (by 30.56 %), thousand-kernel weight (by 36.07 %), and grain yield (by 34.27 %). In contrast, early flowering was increased by 21.67 %. The Dehydrin 6 gene (Dhn6) partial sequences, 770 bp long, were blasted and used to detect SNPs associated with salinity among genotypes. Several SNPs were identified, with 26 variable sites when aligning the partial Dhn6 sequences. Eleven SNPs were identified between the salt-tolerant Giza 137 and salt-sensitive Giza 132 genotypes, all located in exonic regions. These results indicate a potential role in salt tolerance for cultivar Giza 137, and the SNP markers effectively differentiated barley genotypes, which could be useful in salinity breeding programs aimed at developing salinity-tolerant barley and addressing climate change.