Terpene biosynthesis. Part I. Preliminary tracer studies on terpenoids and chlorophyll of Tanacetum vulgare L
Chlorophyll, β-carotene, and the major monoterpenes of Tanacetum vulgare L. were significantly labelled within 1 hour of feeding sodium [1-14C]acetate, but in contrast to results obtained with Mentha species, carbon-14 dioxide was poorly incorporated. The changing patterns of tracer in the plant constituents have been measured over several days and the efficiences of carbon dioxide, sodium acetate, and mevalonic acid, all labelled with carbon-14, as precursors have been established under conditions typical of those used in biosynthetic studies. The results are consistent with the sequence of intermediates in the usually accepted hypothetical scheme for monoterpene biosynthesis, and it is suggested that monoterpenes in vivo in T. vulgare are relatively long-lived and perhaps provide a pool of material for the synthesis of the physiologically important pigments.
Wick-feeding of several 14C-labelled monoterpenes, under conditions that unavoidably must have perturbed the status quo, led to rapid and complex interconversions within this class, and more detailed investigations using [3H]geranyl pyroposphate and [14C]terpinen-4-ol demonstrated the passage of tracer, in addition, into pigments, sugars, and amino-acids.