The Arabidopsis Salt Tolerant Related Protein (STRP) is involved Abscisic Acid signaling and biosynthesis

Environmental stresses are the main cause of crop loss and reduction in agricultural yield. The alteration of gene expression pattern and the accumulation of stress-related protein are the main strategies activated by plants under unfavourable conditions. Here we characterized the Salt Tolerance Related Protein (STRP) that is a new player in stress response in Arabidopsis thaliana. STRP has been identified in a proteomic screening of temperature stress-responsive proteins of A. thaliana. This protein increases strongly under different abiotic stress conditions and knock out mutants are hypersensitive to cold stress damages. The presence of an ABA responsive element (ABRE) in the STRP promoter led us to investigate the role of STRP in abscisic acid signaling. Abscisic acid (ABA) is a phytohormone rapidly accumulated under different abiotic stress conditions and is also involved in different physiological processes such as seed germination, seed dormancy and, stomata closure. ABA induces the increase of STRP into a total cellular extract of A. thaliana and is able to activate STRP expression. We analysed the effects of the hormone plant growth and development by means strp knock-out mutant. The mutant is hyposensitive to the effects of ABA on seed germination and dormancy, primary root elongation, induction of senescence and stomata closure. strp mutant has an altered expression of the ABA-responsive genes and also the ABA biosynthetic genes are impaired. Our results suggest a role for STRP in ABA signaling and perception.