Evaluation of a plant salinity-stress B2-protein gene in wild barley (Hordeum spontaneum) and cultivated barley (Hordeum vulgare L.)

Dehydration-inducing conditions are major factors affecting plants geographic distribution worldwide. Salinity is a major factor affecting crop productivity and survival. Advances in molecular studies enabled scientists to explore salinity and genetic factors that control and contribute to salinity tolerance in plants. We previously identified clones from barley substractive library "from plants growing under high salinity regime" that was similar to previously identified B2-protein gene. In the current study, the relative expression of the B2-protein gene is assessed in wild barley (Hordeum spontaneum) and cultivated barley (Hordeum vulgare L) varieties. Our results indicated that the relative expression of the B2 gene displayed 8.00, 10.34, 12.12 and 11.37 folds at 100 mM NaCl and 4.28, 3.62, 2.70 and 1.58 folds at 200 mM NaCl compared to the non-salt stressed control in wild barley, Giza 129, Giza 132 and Giza 123, respectively. The full-length sequence of the B2 gene (1449 bp) was successfully assembled "accession number MT249004" from wild barley. Comparison studies of the wild barley B2 sequence to its published homologue in cultivated barley indicated the presence of an extra 23 bp long sequence, but its deduced amino acids sequence is five a.a. residues shorter (354 vs. 359 a.a.) with 96.1 % identity. Computational analysis at the protein level indicated the presence of differences in the physicochemical properties between the two proteins. Also, the subcellular localization prediction of the protein revealed the detection of the former protein in the nucleus and the later in the chloroplast. However, the protein modelling and structure prediction do not reveal differences since around 60 % of the protein is disordered. On the other hand, B2-protein interaction predicted networks composed of proteins directly or indirectly associated with the stress responses. In conclusion, the B2- protein gene is a promising candidate for dehydration stress tolerance.