Dehydrodiconiferyl Glucosides and the Control of Plant Cell Division

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Several naturally occurring isomers of dehydrodiconiferyl glucosides (DCGs) can substitute for cytokinin in tobacco pith and leaf cell division bioassays. These DCGs have been found in Vinca rosea and Nicotiana tabacum. In rapidly growing crown gall tumors and non- transformed tissues the DGCs are found in micromolar concentrations whereas in quiescent pith tissues their levels are one hundred fold reduced. These results suggest that cytokinin may exert control of cell division by regulating the accumulation and/or availability of DCGs. The objectives of the proposed work are to: 1) determine the timing and biochemical basis of DCG accumulation after cytokinin treatment of quiescent tissues, 2) determine whether adenylate cytokinins are required for DCG accumulation or vice versa, and 3) initiate studies on the uptake and metabolism of DCGs. The stimulatory effects of the plant hormones auxin and cytokinin on cell division have been known for many years. However, the mechanisms by which these hormones exert their control is not known. Dr. Binns has evidence that implicates dehydrodeconiferyl glucosides in the cell division response to the hormone cytokinin. If this link proves to be a causal one it will provide the first meaningful physiological link between the hormonal signal (cytokinin) and the cellular response (cell division).