Required for constitutive and alternative pre-mRNA splicing (Probable). Involved in primary miRNA processing and pri-miRNA biogenesis. Binds both intronless and intron-containing pri-miRNAs (PubMed:26227967). Component of the spliceosome (Probable). Interacts with RCF3 and CPL1 (PubMed:24146632). Interacts with DRB1/HYL1 and SE (PubMed:26227967). A number of isoforms are produced. According to EST sequences. Leaves, stem, roots and flowers. Mutant seedlings show increased sensitivity to salt stress and abscisic acid (ABA). The splicing pattern of the pre-mRNA is regulated in a tissue-specific manner and by development, and changes in response to various types of abiotic stresses. Belongs to the splicing factor SR family. RS subfamily.