Abstract

Two molecules of coniferyl alcohols are dimerized to form a molecule of pinoresinol , a precursor of podophyllotoxin – antiviral and antitumor agent. The process is catalyzed by pinoresinol synthase (PS). In the present study, the full-length cDNA encoding PS (designated as DtPS) was isolated and characterized from Tibet Dysosma, Dysosma tsayuensis Ying. The full-length DtPS cDNA was 798 bps, and contains a 582-bp open reading frame encoding a 193-amino-acid polypeptide, with a calculated molecular mass of 21.5 kDa and an isoelectric point of 7.24. Comparative analysis indicated that DtPS was similar to other plant PSs in terms of base sequence. The gene tissue- expressing pattern analysis indicated that the expression of DtPS could be detected in all the detected organs including roots, rhizomes, leaves, petioles, flowers and fruits but at different levels. The highest expression level was found in petiole and in fruit, followed by the roots, and lastly by the rhizome, leaf and flower. Cloning and characterization of the PS gene from Tibet Dysosma will facilitate mapping biosynthesis of podophyllotoxin at the molecular level.

Key words: Dysosma tsayuensis Ying, pinoresinol synthase, cloning, expression profile, podophyllotoxin.