Thought to be a Golgi-localized beta-glycan synthase that polymerize the backbones of noncellulosic polysaccharides (hemicelluloses) of plant cell wall. Required for synthesis of a cell wall polysaccharide essential for root hair elongation, but not initiation. May be the functional ortholog of rice CSLD1. Preferentially expressed in root hair cells. Expressed in roots, leaves, stems, flowers and siliques. Belongs to the glycosyltransferase 2 family. Plant cellulose synthase-like D subfamily.