The Proteome Response of Hordeum spontaneum to Salinity Stress

Hordeum spontaneum (wild barley) is a good gene source to improve salt tolerance in barley because it rapidly hybridizes and recombines with barley cultivars. Proteomics can assist in identifying proteins associated with a certain environmental or developmental signal. We employed a proteomic approach to understand the mechanisms of plant responses to salinity in a salt tolerant accession of H. spontaneum. At the 4-leaf stage, wild barley plants were exposed to 0 (control treatment) or 300 mM NaCl (salt treatment). The salt treatment lasted 3 weeks. Total proteins of leaf 4 were extracted and separated by two-dimensional gel electrophoresis. More than 500 protein spots were reproducibly detected. Of these, 29 spots showed significant differences between salt treatment and control. Using MALDI-TOF-TOF MS, we identified 29 cellular proteins, which represented 16 different proteins. These were classified into six categories and a group with unknown biological function. The proteins identified were involved in many different cellular functions. Three spots were identified as unknown proteins; searching in the NCBI database revealed that there was a 71% match with clathrin assembly protein putative [Ricinus communis], a 67% match with actin binding protein [Zea mays], and a 66% match with phosphatidylinositol kinase [Arabidopsis thaliana]. Other proteins identified included ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), oxygen-evolving enhancer protein (OEE), photosystem II reaction center W protein (Psbw), ribosomal proteins, chloroplast RNA binding protein (ChRBP), superoxide dismutase (SOD), malate dehydrogenase (MDH), thioredoxin h (Trx), nucleoside diphosphate kinase (NDPK), profilin, translationally-controlled tumor protein (TCTP), polyamine oxidase (PAO) and universal stress protein family (USP).