Abstract
Plant stem-cell pools, the source for all organs, are first established during embryogenesis. It has been known for decades that cytokinin and auxin interact to control organ regeneration in cultured tissue1. Auxin has a critical role in root stem-cell specification in zygotic embryogenesis2,3, but the early embryonic function of cytokinin is obscure4,5,6. Here, we introduce a synthetic reporter to visualize universally cytokinin output in vivo. Notably, the first embryonic signal is detected in the hypophysis, the founder cell of the root stem-cell system. Its apical daughter cell, the precursor of the quiescent centre, maintains phosphorelay activity, whereas the basal daughter cell represses signalling output. Auxin activity levels, however, exhibit the inverse profile. Furthermore, we show that auxin antagonizes cytokinin output in the basal cell lineage by direct transcriptional activation of ARABIDOPSIS RESPONSE REGULATOR genes, ARR7 and ARR15, feedback repressors of cytokinin signalling. Loss of ARR7 and ARR15 function or ectopic cytokinin signalling in the basal cell during early embryogenesis results in a defective root stem-cell system. These results provide a molecular model of transient and antagonistic interaction between auxin and cytokinin critical for specifying the first root stem-cell niche.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Skoog, F. & Miller, C. O. Chemical regulation of growth and organ formation in plant tissues cultured in vitro. Symp. Soc. Exp. Biol. 54, 118–130 (1957)
Friml, J. et al. Efflux-dependent auxin gradients establish the apical-basal axis of Arabidopsis. Nature 426, 147–153 (2003)
Weijers, D. & Jürgens, G. Auxin and embryo axis formation: the ends in sight? Curr. Opin. Plant Biol. 8, 32–37 (2005)
Riefler, M., Novak, O., Strnad, M. & Schmülling, T. Arabidopsis cytokinin receptor mutants reveal functions in shoot growth, leaf senescence, seed size, germination, root development, and cytokinin metabolism. Plant Cell 18, 40–54 (2006)
Nishimura, C. et al. Histidine kinase homologs that act as cytokinin receptors possess overlapping functions in the regulation of shoot and root growth in Arabidopsis. Plant Cell 16, 1365–1377 (2004)
Higuchi, M. et al. In planta functions of the Arabidopsis cytokinin receptor family. Proc. Natl Acad. Sci. USA 101, 8821–8826 (2004)
To, J. P. et al. Type-A Arabidopsis response regulators are partially redundant negative regulators of cytokinin signaling. Plant Cell 16, 658–671 (2004)
Leibfried, A. et al. WUSCHEL controls meristem function by direct regulation of cytokinin-inducible response regulators. Nature 438, 1172–1175 (2005)
Müller, B. & Sheen, J. Advances in cytokinin signaling. Science 318, 68–69 (2007)
Sakai, H., Aoyama, T. & Oka, A. Arabidopsis ARR1 and ARR2 response regulators operate as transcriptional activators. Plant J. 24, 703–711 (2000)
Hosoda, K. et al. Molecular structure of the GARP family of plant Myb-related DNA binding motifs of the Arabidopsis response regulators. Plant Cell 14, 2015–2029 (2002)
Imamura, A., Kiba, T., Tajima, Y., Yamashino, T. & Mizuno, T. In vivo and in vitro characterization of the ARR11 response regulator implicated in the His-to-Asp phosphorelay signal transduction in Arabidopsis thaliana. Plant Cell Physiol. 44, 122–131 (2003)
Rashotte, A. M., Carson, S. D., To, J. P. & Kieber, J. J. Expression profiling of cytokinin action in Arabidopsis. Plant Physiol. 132, 1998–2011 (2003)
Hwang, I. & Sheen, J. Two-component circuitry in Arabidopsis cytokinin signal transduction. Nature 413, 383–389 (2001)
Yoo, S. D., Cho, Y. H. & Sheen, J. Arabidopsis mesophyll protoplasts: a versatile cell system for transient gene expression analysis. Nature Protocols 2, 1565–1572 (2007)
Gallie, D. R. The 5′-leader of tobacco mosaic virus promotes translation through enhanced recruitment of eIF4F. Nucleic Acids Res. 30, 3401–3411 (2002)
D’Agostino, I. B., Deruere, J. & Kieber, J. J. Characterization of the response of the Arabidopsis response regulator gene family to cytokinin. Plant Physiol. 124, 1706–1717 (2000)
Aloni, R., Langhans, M., Aloni, E. & Ullrich, C. I. Role of cytokinin in the regulation of root gravitropism. Planta 220, 177–182 (2004)
Mähönen, A. P. et al. Cytokinin signaling and its inhibitor AHP6 regulate cell fate during vascular development. Science 311, 94–98 (2006)
Lohar, D. P. et al. Cytokinins play opposite roles in lateral root formation, and nematode and Rhizobial symbioses. Plant J. 38, 203–214 (2004)
Orchard, C. B. et al. Tobacco BY-2 cells expressing fission yeast cdc25 bypass a G2/M block on the cell cycle. Plant J. 44, 290–299 (2005)
Ulmasov, T., Hagen, G. & Guilfoyle, T. J. Dimerization and DNA binding of auxin response factors. Plant J. 19, 309–319 (1999)
Guilfoyle, T., Hagen, G., Ulmasov, T. & Murfett, J. How does auxin turn on genes? Plant Physiol. 118, 341–347 (1998)
Roslan, H. A. et al. Characterization of the ethanol-inducible alc gene-expression system in Arabidopsis thaliana. Plant J. 28, 225–235 (2001)
Sabatini, S., Heidstra, R., Wildwater, M. & Scheres, B. SCARECROW is involved in positioning the stem cell niche in the Arabidopsis root meristem. Genes Dev. 17, 354–358 (2003)
Aida, M. et al. The PLETHORA genes mediate patterning of the Arabidopsis root stem cell niche. Cell 119, 109–120 (2004)
Sarkar, A. K. et al. Conserved factors regulate signalling in Arabidopsis thaliana shoot and root stem cell organizers. Nature 446, 811–814 (2007)
Hass, C. et al. The response regulator 2 mediates ethylene signalling and hormone signal integration in Arabidopsis. EMBO J. 23, 3290–3302 (2004)
Hiratsu, K., Matsui, K., Koyama, T. & Ohme-Takagi, M. Dominant repression of target genes by chimeric repressors that include the EAR motif, a repression domain, in Arabidopsis. Plant J. 34, 733–739 (2003)
Ottenschläger, I. et al. Gravity-regulated differential auxin transport from columella to lateral root cap cells. Proc. Natl Acad. Sci. USA 100, 2987–2991 (2003)
Weijers, D. et al. An Arabidopsis Minute-like phenotype caused by a semi-dominant mutation in a RIBOSOMAL PROTEIN S5 gene. Development 128, 4289–4299 (2001)
Xiang, C., Han, P., Lutziger, I., Wang, K. & Oliver, D. J. A mini binary vector series for plant transformation. Plant Mol. Biol. 40, 711–717 (1999)
Sauer, M. & Friml, J. In vitro culture of Arabidopsis embryos within their ovules. Plant J. 40, 835–843 (2004)
Laureys, F. et al. Zeatin is indispensable for the G2-M transition in tobacco BY-2 cells. FEBS Lett. 426, 29–32 (1998)
Laule, O. et al. Crosstalk between cytosolic and plastidial pathways of isoprenoid biosynthesis in Arabidopsis thaliana. Proc. Natl Acad. Sci. USA 100, 6866–6871 (2003)
Di Laurenzio, L. et al. The SCARECROW gene regulates an asymmetric cell division that is essential for generating the radial organization of the Arabidopsis root. Cell 86, 423–433 (1996)
Acknowledgements
We thank T. Kakimoto and C. Ueguchi for providing ahk mutant seeds; J. Friml for the DR5::GFP plasmid and DR5::GFP seeds; E. Lam for providing the AlcA/AlcR vector; A. Jazwinska for help with mRNA in situ hybridizations; and S. Riku for help with plant growth and protoplast experiments. We also thank C. Ping, S. Howell, Y. Guo, Y. Tan, G. Selvaraj, T. Mizuno, J. Zuo, D. Jackson and J. To for sharing unpublished results. This work was supported by a Fellowship for Prospective Researchers by the Swiss National Science Foundation, a Long Term Fellowship of the International Human Frontier Science Program organization to B.M., and grants from the National Science Foundation and National Institutes of Health to J.S.
Author Contributions B.M. initiated the project, performed the experiments and analysed the data; B.M. and J.S. discussed the results, planned the experiments and wrote the manuscript.
Author information
Authors and Affiliations
Corresponding authors
Supplementary information
Supplementary Figures
The file contains Supplementary Figures S1-S13 with Legends. (PDF 2097 kb)
Rights and permissions
About this article
Cite this article
Müller, B., Sheen, J. Cytokinin and auxin interaction in root stem-cell specification during early embryogenesis. Nature 453, 1094–1097 (2008). https://doi.org/10.1038/nature06943
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/nature06943
This article is cited by
-
ARGONAUTE10 controls cell fate specification and formative cell divisions in the Arabidopsis root
The EMBO Journal (2024)
-
Melatonin Antagonizes Cytokinin Responses to Stimulate Root Growth in Arabidopsis
Journal of Plant Growth Regulation (2023)
-
Involvement of cytokinins in STOP1-mediated resistance to proton toxicity
Stress Biology (2022)
-
PEPC of sugarcane regulated glutathione S-transferase and altered carbon–nitrogen metabolism under different N source concentrations in Oryza sativa
BMC Plant Biology (2021)
-
Azospirillum brasilense Sp245 triggers cytokinin signaling in root tips and improves biomass accumulation in Arabidopsis through canonical cytokinin receptors
Physiology and Molecular Biology of Plants (2021)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.