Salt Tolerance-Related Protein (STRP): a new player involved in cold and salt stress responses in Arabidopsis thaliana.

Abiotic stresses are the main factors affecting plant survival and crop yield. The identification of stress-responsive proteins is the main goal of plant stress physiologists. The Salt Tolerance-Related protein (STRP) is a stress-responsive protein involved in response to cold and salt stress in A. thaliana. STRP levels strongly increase in both stresses due to the reduction of proteasome-mediated degradation. Primary structure analysis of STRP demonstrated that the protein shares some features with LEA proteins, such as the high hydrophilicity and the presence of extensive intrinsically disordered domains. In vitro and in vivo assays demonstrated that STRP has cryoprotectant and anti-ROS activity. Physiological and biochemical analysis performed on strp mutant and STRP overexpressing plants under both cold and salt stress revealed that protein reduces the adverse effects of stresses on a wide range of processes, e.g., seed germination and seedlings growth, and on oxidative damage induced by stresses. The strp mutant displays altered ABA-regulated processes and hormone levels. Protein localization reveals that STRP is located at the plasma membrane, in the cytosol, and in the nucleus, where it interacts with chromatin and the chromatin-remodeling protein DEK3. Altogether, these findings propose STRP as a critical component of the response mechanisms to cold and saline stress in A. thaliana.