DETERMINATION OF THE CYTOKININ COMPLEMENT IN HEALTHY AND WITCHESBROOM MALFORMED PROTEAS

Cytokinins from normal and witches-broom malformed stems of proteas were determined by radioimmunoassay following sample resolution by high-performance liquid chromatography (HPLC). Material from the early stages of shoot malformation had increased cytokinin concentrations which, over time, declined to the concentrations found in normal-growing stems. The cytokinin complement of the malformed structures was different from that of normal stems. The high concentrations of isopentenyladenosine detected appear to be related to the loss of the correlative inhibition of lateral buds and the development of the witches-broom structures and may result from localized changes in cytokinin biosynthesis and/or metabolism.