Non-catalytic component of the RNA exosome complex which has 3'->5' exoribonuclease activity and participates in a multitude of cellular RNA processing, maturation and degradation events. In vitro, is a processive phosphorolytic exonuclease and requires a single-stranded poly(A) tail on the substrate RNA for its activity (By similarity). Plays an important role in seed germination and early seedling growth by mediating specific cytoplasmic mRNA decay of transcripts coding for the abscisic acid (ABA) biosynthetic enzymes NCED5 and NCED6, and the ABA signaling transcription factors ABI3 and ABI4 (PubMed:23132787). Probable component of the RNA exosome complex. Highly expressed in imbibed seeds and young seedlings. Extremely slow growth, especially during the early stage of development. Belongs to the RNase PH family.