Cloning and Expression Analysis of Cinnamyl Alcohol Dehydrogenase (SmCAD) Gene in Salvia miltiorrhiza Bunge

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the reduction reaction of cinnamic aldehyde and its derivatives depending on the NADPH.It is the key enzyme in the last step of lignin biosynthesis. A novel CAD gene designated as SmCAD (GenBank accession No.: HQ162287) was cloned from Salvia miltiorrhiza Bunge according to the transcription databases. It contained a 1083 bp open reading frame, including 3 introns and 4 exons, and encoded a protein of 360 amino acids. The predicted SmCAD protein had Zn1 and Zn2 binding sites and NADP(H) binding domain. A total of 1202 bp promoter sequences were obtained using BD walking method, and sequence analysis revealed that there were MeJA, ABA, GA₃ response elements and MYB binding sites. Real-time quantitative PCR showed that SmCAD was expressed in different organs, and its expression was induced by MeJA and inhibited by GA₃. These results suggested that this gene may be involved in the response of exogenous signals. This study contributes to the theoretical basis of the specific function of SmCAD.