Metabolism and compartmentation of dihydrozeatin exogenously supplied to photoautotrophic suspension cultures of Chenopodium rubrum

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Abstract
[3H]Dihydrozeatin supplied to photoautotrophically growing cell suspension cultures of Chenopodium rubrum was rapidly taken up and metabolized by the cells. The predominant metabolites in extracts of the cells were [3H]dihydrozeatin-O-glucoside and [3H]dihydrozeatin riboside-O-glucoside. Both these compounds could be shown to be compartmented within the vacuole, whereas [3H]dihydrozeatin and [3H]dihydrozeatin riboside, which were both present to a minor extent in cell extracts, were both present to a minor extent in cell extracts, were localized predominantly outside the vacuole. Analysis of the culture medium at the end of the 36-h incubation period showed that there had been an efflux of [3H]dihydrozeatin metabolites out of the cells. Whereas [3H]dihydrozeatin riboside was found to be the major extracellular [3H]dihydrozeatin metabolite, the O-glucosides of neither this compound nor [3H]dihydrozeatin could be detected in the medium. The differential compartmentation of [3H]dihydrozeatin metabolites found with the C. rubrum suspension-culture system is discussed with respect to possible mechanisms governing the metabolism of cytokinins in plants cells.