Dual Roles of the Serine/Arginine-rich Splicing Factor SR45a in Promoting and Interacting with Nuclear Cap-binding Complex to Modulate the Salt Stress Response in Arabidopsis

We discovered that a conserved SR-like protein, SR45a, as a component of the spliceosome, was involved in post-transcriptional regulation of salinity tolerance in Arabidopsis thaliana. Furthermore, SR45a was required for the AS and mRNA maturation of several salt-tolerance genes. Two alternatively spliced variants of SR45a were induced by salt stress, full-length SR45a-1a and the truncated isoform SR45a-1b, respectively. Lines with overexpression of SR45a-1a and SR45a-1b exhibited supersensitive to salt stress.