Alpha-1-4-D-galacturonosyltransferase involved in homogalacturonan (HGA) synthesis, a class of pectin which plays a role in cell adhesion. Glycan metabolism; pectin biosynthesis. Expressed in roots, inflorescences, flowers, siliques, leaves and stems. Localized to discrete cells of the vascular tissue and subepidermal layers. Expressed at both the vegetative and floral stages. Embryo lethality. Reduced galacturonic acid and xylose content in cell wall. Altered cell wall porosity. Reduced vascular bundle. Belongs to the glycosyltransferase 8 family.