Proteomic analysis of salt-responsive proteins in the leaves of two contrasting Tunisian barley landraces

Salinity is a brutal environmental factor that severely affects barley growth and development. In this context, local landraces, commonly cultivated under stressful conditions, could represent important reservoirs of valuable traits in barley breeding programs. Therefore, understanding salt-tolerance mechanisms in such genotypes is of great interest. Here, based on a 2D-PAGE comparative proteomic study, salt-induced proteome changes were explored in the seedling leaves of two contrasting Tunisian landraces, namely Boulifa (tolerant) and Testour (sensitive). The analysis showed that 11 salt-responsive proteins were differentially accumulated in both accessions under salt stress and 43 were genotype-specific (18 in Boulifa and 25 in Testour). Using mass spectrometry identification and annotation, 11 function categories revealed being involved in salt-stress response, specifically the defense/cell wall related metabolism. In fact, a chitinase, was up-regulated in the tolerant accession and down-regulated in the sensitive one in addition to a ricin B-like lectin R40G3 as well as a predicted BSP that were up-regulated in the tolerant one. Then, two other chitinases, PR10, glucan endo-1.3-beta-glucosidase, were down-regulated in Testour, while still unchanged in the tolerant accession Boulifa. In the latter, signaling, redox/polyamine catabolism and the energy metabolism were found as part of the biochemical pathways underlying salt-tolerance. These results suggest that Boulifa may alleviate salt stress by activation of specific defense responses, and adjustment of both redox/polyamine catabolism and energy metabolism processes. Our findings represent a basis that would assist selection of candidates as markers in improving barley salt tolerance and elite genotypes creation.