The metabolism of isoprenoid precursors in a plant system

It has been shown earlier(1,2) that the synthesis of the isoprenoid, rubber, by a rubber-bearing plant, guayule (Parthenium argentatum), involves acetate as an, intermediate. Not only does the administration of acetate to this plant result in a net increase in the amount of rubber formed, but, in addition, rubber synthesized by plants supplied with doubly C14-labeled acetate possesses the same specific activity as the acetate given, indicating that all the carbon atoms of the rubber derive from and channel through acetate.(3) Rubber, like other isoprenoids, is made up of repeating units of isoprene, which has the five-carbon branched-chain structure shown below. This structure appears, then, to be derived in the plant from acetate.