Involved in stem and root growth. Possesses xylan and homogalacturonan synthase activity. Expressed in vascular tissues. Expressed at its highest level between 21 and 25 days, during the inflorescence stem elongation phase. Significant reduction of root and stem growth, xylan reduction in stem and increased susceptibility to the cellulose synthase inhibitor isoxaben. Belongs to the glycosyltransferase 2 family. Plant cellulose synthase-like D subfamily.