ISOLATION OF CINNAMYL ALCOHOL-DEHYDROGENASE CDNAS FROM 2 IMPORTANT ECONOMIC SPECIES - ALFALFA AND POPLAR - DEMONSTRATION OF A HIGH HOMOLOGYOF THE GENE WITHIN ANGIOSPERMS

Cinnamyl alcohol dehydrogenase (CAD), a key enzyme in lignification, w as cloned from poplar (Populus trichocarpa x P. deltoides) and alfalfa (Medicago sativa L.). Both cDNAs contain one continuous open reading frame encoding a protein of 357 amino acid residues (M(r) 39,036) for the poplar CAD and 358 amino acids (M(r) 38,950) for the alfalfa CAD. Comparison of the poplar and alfalfa CAD with other reported plant CAD sequences confirms the identity of the isolated cDNAs and shows the p oplar and alfalfa CAD to be closely related to CAD from tobacco, eucal yptus and Aralia cordata (80% amino acid identity) while 70% amino aci d identity was found with the CAD from the gymnosperm spruce. Sequence comparisons allowed also to identify important conserved domains and specific functional motifs.