Proteomic and phosphoproteomic analyses of NaCl stress-responsive proteins in Arabidopsis roots

Salt is one of the major abiotic stresses limiting the productivity and the geographical distribution of crops. To gain a better understanding of NaCl stress responses in model plant Arabidopsis roots, the protein changes in the abundance (Coomassie Brilliant Blue R-350 stain) and phosphorylation (Pro-Q Diamond stain) were examined using two-dimensional electrophoresis coupled with mass spectrometry (MS). Seventeen unique proteins differentially changed in abundance, phosphorylation, or both in response to NaCl. Nonsynchronous differences were found between total proteins and phosphorylated proteins. Protein synthesis, proteolysis, post-translational modifications, and isoforms might cause the differential protein redundancies. The identified proteins are involved in binding, catalysis, signal transduction, transport, metabolisms of cell wall and energy, and reactive oxygen species (ROS) scavenging and defense. These protein changes provide new avenues of investigation into the underlying salt stress response in Arabidopsis roots and demonstrate the advantages of proteomic approach in plant biology studies.