Multiple feedback loops through cytokinin signaling control stem cell number within the Arabidopsis shoot meristem
Abstract
A central unanswered question in stem cell biology, both in plants and in animals, is how the spatial organization of stem cell niches are maintained as cells move through them. We address this question for the shoot apical meristem (SAM) which harbors pluripotent stem cells responsible for growth of above-ground tissues in flowering plants. We find that localized perception of the plant hormone cytokinin establishes a spatial domain in which cell fate is respecified through induction of the master regulator WUSCHEL as cells are displaced during growth. Cytokinin-induced WUSCHEL expression occurs through both CLAVATA-dependent and CLAVATA-independent pathways. Computational analysis shows that feedback between cytokinin response and genetic regulators predicts their relative patterning, which we confirm experimentally. Our results also may explain how increasing cytokinin concentration leads to the first steps in reestablishing the shoot stem cell niche in vitro.
Additional Information
© 2009 National Academy of Sciences. Contributed by Elliot M. Meyerowitz, July 27, 2009 (received for review June 3, 2009). Published online before print August 26, 2009, doi: 10.1073/pnas.0908122106. We thank P. Benfey for the pWOODENLEG::GFP line referred to here as the AHK4 reporter, pAHK4::GFP. The pARR5::GFP line was provided by J. Kieber and Y. Helariutta provided the pAHP6::AHP6-GFP line. Cytokinin receptor mutants were provided by T. Kakimoto. We thank the Computable Plant group (http://computableplant.org/) including H. Jönsson, M. Heisler, A. Roeder, and P. Tarr for comments on the manuscript; K. Sugimoto for advice with RT-PCR analysis of treated root explants; A. Martin for sample collection of cytokinin serial dilutions; and A. Garda for technical support. This study was supported by National Science Foundation grants IOS-0846192 and IOS-0544915 to E.M.M. Author contributions: S.P.G. and V.S.C. designed research; S.P.G. performed research; C.O. contributed new reagents/analytic tools; V.S.C. performed the computational analysis and model building; S.P.G., V.S.C., and E.M.M. analyzed data; and S.P.G., V.C., and E.M.M. wrote the paper. The authors declare no conflict of interest. This article contains supporting information online at www.pnas.org/cgi/content/full/0908122106/DCSupplemental.Attached Files
Published - Gordon2009p6022P_Natl_Acad_Sci_Usa.pdf
Supplemental Material - 0908122106SI.pdf
Supplemental Material - Appendix_PDF.pdf
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Additional details
- PMCID
- PMC2752578
- Eprint ID
- 16292
- Resolver ID
- CaltechAUTHORS:20091013-093447174
- IOS-0846192
- NSF
- IOS-0544915
- NSF
- Created
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2009-10-21Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field