THE QUANTITATIVE CONTRIBUTION OF SUCROSE AND THREONINE TO TRITERPENOID PRODUCTION IN THE ETIOLATED SEEDLING OF EUPHORBIA-LATHYRIS L

Seedlings, 9-10-days old, were used to estimate their potential to synthesize sterols, latex triterpenols and wax triterpene ketones from sucrose and threonine. The endosperms of these seedlings were removed and replaced by solutions with various concentrations of C-14-sucrose or C-14-threonine. The triterpenoid synthesis from these substrates was measured after 24 h of incorporation. The maximum production of triterpenols and triterpene ketones from exogenously supplied sucrose in such a seedling matched the daily synthesis of these triterpenoids in the seedling with endosperm. About 50% of the daily triterpenoid synthesis is derived from sucrose, in the production period taken up by the cotyledons from the endosperm or a substituting solution. The other part was mainly produced from sugars deposited in the seedling in previous days of uptake. The potential of the seedling to synthesize triterpenoids from externally supplied threonine is less than 10% of that from sucrose. In the intact seedling, only a small fraction of the potential production capacity from threonine is used for triterpenoid synthesis.