Isolation and characterization of a new, full-length cellulose synthase cDNA, PtrCesA5 from developing xylem of aspen trees.

Cellulose synthases (CesA) represent a group of beta-1,4 glycosyltransferases involved in cellulose biosynthesis. Recent molecular studies confirmed that a large CesA gene family encoding various CesA isoforms exists in plants. The isolation and characterization of a new, full-length CesA cDNA, PtrCesA5 from an economically important tree, quaking aspen (Populus tremuloides) is reported here. The predicted PtrCesA5 protein is highly similar to Arabidopsis AtCesA3 (88%) involved in primary cell wall synthesis. However, gene expression studies here suggest that PtrCesA5 transcripts are greatly enhanced in developing xylem tissues enriched in secondary cell wall synthesis as compared with leaf tissues actively undergoing primary cell wall synthesis. Availability of this new, dual-function CesA from a woody species will assist in a better understanding of the mechanism of cellulose biosynthesis during wood development.