Beta-arabinofuranosyltransferase that transfers specifically an arabinosyl residue from UDP-arabinofuranose to the monosaccharide galactose or beta-methyl-galactoside in vitro. Catalyzes the addition of a beta-arabinofuranose residue onto a beta-galactosyl residue of an Yariv-precipitable wall polymer in vivo. The conserved DXD motif is involved in enzyme activity. Reduced growth of primary root. Delayed flowering. Belongs to the glycosyltransferase 77 family.