CINNAMYL ALCOHOL-DEHYDROGENASE FROM ARALIA-CORDATA - CLONING OF THE CDNA AND EXPRESSION OF THE GENE IN LIGNIFIED TISSUES

A full-length cDNA clone encoding a subunit of cinnamyl alcohol dehydr ogenase (CAD) was isolated from a perennial dicot, Aralia cordata. The identity of the clone was demonstrated by two criteria: (i) the amino acid sequences of peptides derived from the purified CAD protein of A . cordata were highly homologous to regions of the amino acid sequence deduced from the nucleotide sequence of the cDNA; and (ii) a fusion p rotein expressed from lambdagt11 that carried part of the cDNA reacted with an antibody raised against purified CAD protein. Amino-terminal sequencing of the protein indicated that the mature protein is shorter by two amino acids at the amino terminus than the protein predicted f rom the nucleotide sequence. The level of expression of the gene was h igher in stems than in leaves and roots, consistent with the degree of lignification of these tissues. A comparison of amino acid sequences indicated that CAD is a member of the family of alcohol dehydrogenases .