Molecular mechanism of cytokinin-activated cell division in <i>Arabidopsis</i>
Weibing Yang, Sandra Cortijo, Niklas Korsbo, Pawel Roszak, Katharina Schiessl, A. V. Gurzadyan, Raymond Wightman, Henrik Jönsson, Elliot M. Meyerowitz
Abstract
shoot apical meristem (SAM), cytokinin regulates cell division by promoting nuclear shuttling of Myb-domain protein 3R4 (MYB3R4), a transcription factor that activates mitotic gene expression. Newly synthesized MYB3R4 protein resides predominantly in the cytoplasm. At the G2-to-M transition, rapid nuclear accumulation of MYB3R4-consistent with an associated transient peak in cytokinin concentration-feeds a positive feedback loop involving importins and initiates a transcriptional cascade that drives mitosis and cytokinesis. An engineered nuclear-restricted MYB3R4 mimics the cytokinin effects of enhanced cell proliferation and meristem growth.