ADENINE METABOLISM AND THE SYNTHESIS OF PURINE ALKALOIDS IN FLOWERS OF CAMELLIA

Concentrations of purine alkaloids in stamens and petals of Camellia plants were determined. Caffeine was present in both stamens and petals, but significant amounts of theobromine were found only in the stamens of C. sinensis. In C. irrawadiensis, theobromine accumulated both in stamens and in petals. In contrast, no purine alkaloid was detectable in flower buds of C. japonica and C. sasanqua. The pattern of accumulation of purine alkaloids in the flower buds of a hybrid plant (C. sinensis x C. japonica) was similar to that of C. sinensis, but concentrations of the alkaloids were lower. Tracer experiments using [8-14C]adenine indicated that the biosynthetic pathway to caffeine was operative in the stamens and petals of C. sinensis and of the hybrid, but the reaction from theobromine to caffeine was deficient in C. irrawadiensis, while the entire series of reactions required for the synthesis of purine alkaloids was deficient in both C. japonica and C.sasanqua. Conventional 'salvage' and degradation pathways for purines were present in the stamens and petals of all Camellia plants examined, but the flux of the degradation pathway was generally higher in Camellia plants that did not accumulate purine alkaloids than in the flowers of the alkaloid-producing species. © 1990.