Probable glycosyltransferase involved in the O-arabinosylation of several proteins including extensins and small signaling peptides (Probable). Catalyzes the transfer of the initial L-arabinose to the hydroxyl group of Hyp residues (Probable). Probably involved in the arabinosylation of CLE12, a signaling peptide that moves from root to shoot, to interact with SUNN receptor kinase signaling that regulates nodulation (Probable). Involved in long distance nodulation signaling events (Probable) (PubMed:21742814). Involved in the autoregulation of nodulation (AON), a long distance systemic signaling from root to shoot and back again, which allows legumes to limit the number of root nodules formed based on available nitrogen and previous rhizobial colonization (PubMed:27135324, PubMed:28592666). Functions in the root, upstream of the shoot receptor kinase SUNN and via CLE peptide, to control AON (PubMed:28592666). trans-4-hydroxy-L-prolyl-[protein] + UDP-beta-L-arabinofuranose = H(+) + O-(beta-L-arabinofuranosyl)-trans-4-hydroxy-L-prolyl-[protein] + UDP Expressed in the vasculature of leaves, petioles, stems and roots (PubMed:22301956). Expressed in the vascular cylinder throughout the root, and nodule vasculature (PubMed:21742814). Dramatic increase in root nodule number when inoculated with Sinorhizobium medicae (PubMed:21742814, PubMed:28592666). Inhibition of root growth in both the presence and absence of rhizobia (PubMed:21742814, PubMed:28592666). Truncated N-terminus.