Possesses 5'->3' exoribonuclease activity (PubMed:11106401). Acts as an endogenous post-transcriptional gene silencing (PTGS) suppressor. Degrades miRNA-derived loops, excised during miRNA maturation in the nucleus. Required for proper development (PubMed:17993620). Involved in pre-rRNA processing. Involved with XRN2 in the 5'-end exonucleolytic processing of 5.8S and 25S rRNAs. Contributes with XRN2 to polyadenylation-dependent nuclear RNA surveillance. Involved in the degradation of aberrant polyadenylated pre-rRNA through 5'-end processing (PubMed:20338880). Expressed in roots, leaves, stems and flowers. Embryonic lethality. Belongs to the 5'-3' exonuclease family. XRN2/RAT1 subfamily.