The architecture of a plant's root system, established postembryonically, results from both coordinated root growth and lateral root branching. The plant hormones auxin and cytokinin are central endogenous signaling molecules that regulate lateral root organogenesis positively and negatively, respectively. Tight control and mutual balance of their antagonistic activities are particularly important during the early phases of lateral root organogenesis to ensure continuous lateral root initiation (LRI) and proper development of lateral root primordia (LRP). Here, we show that the early phases of lateral root organogenesis, including priming and initiation, take place in root zones with a repressed cytokinin response. Accordingly, ectopic overproduction of cytokinin in the root basal meristem most efficiently inhibits LRI. Enhanced cytokinin responses in pericycle cells between existing LRP might restrict LRI near existing LRP and, when compromised, ectopic LRI occurs. Furthermore, our results demonstrate that young LRP are more sensitive to perturbations in the cytokinin activity than are developmentally more advanced primordia. We hypothesize that the effect of cytokinin on the development of primordia possibly depends on the robustness and stability of the auxin gradient.
The Plant Cell
We thank Jen Sheen, Dolf Weijers, Tatsuo Kakimoto, Stephen Depuydt, and Laurent Laplaze for sharing published material, Jiri Friml for discussions, and Martine De Cock and Annick Bleys for help in preparing the manuscript. This work was supported by a Starting Independent Research grant from the European Research Council (ERC-2007-Stg-207362-HCPO) and the project CZ.1.07/2.3.00/20.0043 to the Central European Institute of Technology to E.B. and grants from the Ministry of Education, Youth, and Sports of the Czech Republic (MSM 6198959216) and the Centre of the Region Haná for Biotechnological and Agricultural Research (ED0007/01/01) to P.T.
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Bielach A, Podlesakova K, Marhavý P, et al. Spatiotemporal regulation of lateral root organogenesis in Arabidopsis by cytokinin. The Plant Cell. 2012;24(10):3967-3981. doi:10.1105/tpc.112.103044
Bielach, A., Podlesakova, K., Marhavý, P., Duclercq, J., Cuesta, C., Muller, B., … Benková, E. (2012). Spatiotemporal regulation of lateral root organogenesis in Arabidopsis by cytokinin. The Plant Cell. American Society of Plant Biologists. https://doi.org/10.1105/tpc.112.103044
Bielach, Agnieszka, Katerina Podlesakova, Peter Marhavý, Jérôme Duclercq, Candela Cuesta, Bruno Muller, Wim Grunewald, Petr Tarkowski, and Eva Benková. “Spatiotemporal Regulation of Lateral Root Organogenesis in Arabidopsis by Cytokinin.” The Plant Cell. American Society of Plant Biologists, 2012. https://doi.org/10.1105/tpc.112.103044.
A. Bielach et al., “Spatiotemporal regulation of lateral root organogenesis in Arabidopsis by cytokinin,” The Plant Cell, vol. 24, no. 10. American Society of Plant Biologists, pp. 3967–3981, 2012.
Bielach A, Podlesakova K, Marhavý P, Duclercq J, Cuesta C, Muller B, Grunewald W, Tarkowski P, Benková E. 2012. Spatiotemporal regulation of lateral root organogenesis in Arabidopsis by cytokinin. The Plant Cell. 24(10), 3967–3981.
Bielach, Agnieszka, et al. “Spatiotemporal Regulation of Lateral Root Organogenesis in Arabidopsis by Cytokinin.” The Plant Cell, vol. 24, no. 10, American Society of Plant Biologists, 2012, pp. 3967–81, doi:10.1105/tpc.112.103044.