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 Arabidopsis CSLD3/KOJAK. Specifically expressed in root hair cells. Down-regulated by 1-N-naphthylphthalamic acid (NPA), an auxin efflux inhibitor. Plants develop short elongated root hair with kinks and swellings along their length. Belongs to the glycosyltransferase 2 family. Plant cellulose synthase-like D subfamily.