BIOSYNTHESIS OF CEMBRATRIENOLS IN CELL-FREE-EXTRACTS FROM TRICHOMES OF NICOTIANA-TABACUM

Biosynthesis of alpha- and beta-2,7,11-cembratriene-4-ol from all-trans-[1-H-3]geranylgeranyl pyrophosphate was observed in cell-free extracts prepared from leaf midvein epidermal peels bearing trichome glands and isolated glands of several cembranoid producing tobacco cultivars. The activity yielded both cembratriene-4-ol diastereomers and resembled other plant terpene cyclase activities in solubility, molecular weight, pH optimum and dependence on the divalent cation Mg2+. Partial purification of the activity indicates that the enzyme consists of a single polypeptide of 58 kDa. It is concluded that cembratriene-4-ols rather than cembrene are products of the cyclization of geranylgeranyl pyrophosphate, and that cembratriene-4-ols are probable precursors of cembratriene-4,6-diols in vivo. The putative enzyme that hydroxylates the mono-alcohols to form the diols is apparently inactivated during detachment and recovery of trichome glands.