article published Kamil Růžička author Mária Šimášková author Jérôme Duclercq author Jan Petrášek author Eva Zažímalová author Sibu Simon author 4542EF9A-F248-11E8-B48F-1D18A9856A870000-0002-1998-6741 Jirí Friml author 4159519E-F248-11E8-B48F-1D18A9856A870000-0002-8302-7596 Marc Van Montagu author Eva Benková author 38F4F166-F248-11E8-B48F-1D18A9856A870000-0002-8510-9739 Plant development is governed by signaling molecules called phytohormones. Typically, in certain developmental processes more than 1 hormone is implicated and, thus, coordination of their overlapping activities is crucial for correct plant development. However, molecular mechanisms underlying the hormonal crosstalk are only poorly understood. Multiple hormones including cytokinin and auxin have been implicated in the regulation of root development. Here we dissect the roles of cytokinin in modulating growth of the primary root. We show that cytokinin effect on root elongation occurs through ethylene signaling whereas cytokinin effect on the root meristem size involves ethylene-independent modulation of transport-dependent asymmetric auxin distribution. Exogenous or endogenous modification of cytokinin levels and cytokinin signaling lead to specific changes in transcription of several auxin efflux carrier genes from the PIN family having a direct impact on auxin efflux from cultured cells and on auxin distribution in the root apex. We propose a novel model for cytokinin action in regulating root growth: Cytokinin influences cell-to-cell auxin transport by modification of expression of several auxin transport components and thus modulates auxin distribution important for regulation of activity and size of the root meristem. National Academy of Sciences2009 10.1073/pnas.0900060106 106114284 - 4289 yes Růžička K, Šimášková M, Duclercq J, Petrášek J, Zažímalová E, Simon S, Friml J, Van Montagu M, Benková E. 2009. Cytokinin regulates root meristem activity via modulation of the polar auxin transport. PNAS. 106(11), 4284–4289. Růžička, Kamil, et al. “Cytokinin Regulates Root Meristem Activity via Modulation of the Polar Auxin Transport.” <i>PNAS</i>, vol. 106, no. 11, National Academy of Sciences, 2009, pp. 4284–89, doi:<a href="https://doi.org/10.1073/pnas.0900060106">10.1073/pnas.0900060106</a>. Růžička, Kamil, Mária Šimášková, Jérôme Duclercq, Jan Petrášek, Eva Zažímalová, Sibu Simon, Jiří Friml, Marc Van Montagu, and Eva Benková. “Cytokinin Regulates Root Meristem Activity via Modulation of the Polar Auxin Transport.” <i>PNAS</i>. National Academy of Sciences, 2009. <a href="https://doi.org/10.1073/pnas.0900060106">https://doi.org/10.1073/pnas.0900060106</a>. K. Růžička <i>et al.</i>, “Cytokinin regulates root meristem activity via modulation of the polar auxin transport,” <i>PNAS</i>, vol. 106, no. 11. National Academy of Sciences, pp. 4284–4289, 2009. Růžička K, Šimášková M, Duclercq J, et al. Cytokinin regulates root meristem activity via modulation of the polar auxin transport. <i>PNAS</i>. 2009;106(11):4284-4289. doi:<a href="https://doi.org/10.1073/pnas.0900060106">10.1073/pnas.0900060106</a> K. Růžička, M. Šimášková, J. Duclercq, J. Petrášek, E. Zažímalová, S. Simon, J. Friml, M. Van Montagu, E. Benková, PNAS 106 (2009) 4284–4289. Růžička, K., Šimášková, M., Duclercq, J., Petrášek, J., Zažímalová, E., Simon, S., … Benková, E. (2009). Cytokinin regulates root meristem activity via modulation of the polar auxin transport. <i>PNAS</i>. National Academy of Sciences. <a href="https://doi.org/10.1073/pnas.0900060106">https://doi.org/10.1073/pnas.0900060106</a> 30502018-12-11T12:01:04Z2021-01-12T07:40:42Z