Biosynthesis of plaunotol in Croton stellatopilosus proceeds via the deoxyxylulose phosphate pathway

Plaunotol, an acyclic diterpene alcohol that accumulates in the chloroplasts of Croton stellatopilosus leaves, was studied for its origin of isoprene units. Separate feedings of [U-13C]glucose and [1-13C]glucose into cut shoots of the plant showed that the labels from glucose were incorporated into plaunotol. NMR analysis of the purified plaunotol revealed that all four isoprene units of the molecule had the same labeling pattern which is consistent with exclusive acquisition via the deoxyxylulose phosphate pathway. The results of in vivo feeding experiments suggested that there was no significant metabolite exchange taking place between the mevalonate pathway and the deoxyxylulose pathway during the biosynthesis of plaunotol in this Croton stellatopilosus.