Molecular mechanism of cytokinin-activated cell division in Arabidopsis

Mitogens trigger cell division in animals. In plants, cytokinins, a group of phytohormones derived from adenine, stimulate cell proliferation. Cytokinin signaling is initiated by membrane-associated histidine kinase receptors and transduced through a phosphorelay system. We show that in the Arabidopsis 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.

Source: ScienceNOW - March 25, 2021 Category: Science Authors: Yang, W., Cortijo, S., Korsbo, N., Roszak, P., Schiessl, K., Gurzadyan, A., Wightman, R., Jönsson, H., Meyerowitz, E. Tags: Botany, Cell Biology r-articles Source Type: news