Involved in the biosynthesis of beta-1,4-galactan. Beta-1,4-galactans are abundant polysaccharides in plant cell walls and are found as side-chain of rhamnogalacturonan I, which is a major component of pectin. Expressed in the midrib of mature leaves, root vasculature, flower filaments, siliques and seeds. No visible phenotype under normal growth conditions, but mutant plants have reduced content of beta-1,4-galactan in leaf cell wall. Belongs to the glycosyltransferase 92 family.