Mobile PEAR transcription factors integrate positional cues to prime cambial growth.
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Miyashima, S., Roszak, P., Sevilem, I., Toyokura, K., Blob, B., Heo, J., Mellor, N., et al. (2019). Mobile PEAR transcription factors integrate positional cues to prime cambial growth.. Nature, 565 (7740), 490-494. https://doi.org/10.1038/s41586-018-0839-y
While apical growth in plants initiates upon seed germination, radial growth is only primed during early ontogenesis in procambium cells and activated later by the vascular cambium1. Although it is not known how radial growth is organized and regulated in plants, this system resembles the developmental competence observed in some animal systems, in which pre-existing patterns of developmental potential are established early on2,3. Here we show that the initiation of radial growth occurs around early protophloem sieve element (PSE) cell files of the root procambial tissue in Arabidopsis. In this domain cytokinin signalling promotes expression of a pair of novel mobile transcription factors, PHLOEM EARLY DOF (PEAR1, PEAR2) and their four homologs (DOF6, TMO6, OBP2 and HCA2), collectively called PEAR proteins. The PEAR proteins form a short-range concentration gradient peaking at PSE and activating gene expression that promotes radial growth. The expression and function of PEAR proteins are antagonized by well-established polarity transcription factors, HD-ZIP III4, whose expression is concentrated in the more internal domain of radially non-dividing procambial cells by the function of auxin and mobile miR165/166. The PEAR proteins locally promote transcription of their inhibitory HD-ZIP III genes, thereby establishing a negative feedback loop that forms a robust boundary demarking the zone of cell divisions. Taken together, we have established a network, in which the PEAR - HD-ZIP III module integrates spatial information of the hormonal domains and miRNA gradients during root procambial development, to provide adjacent zones of dividing and more quiescent cells as a foundation for further radial growth.
Arabidopsis, Plant Roots, Indoleacetic Acids, Plant Growth Regulators, Cytokinins, Arabidopsis Proteins, Transcription Factors, MicroRNAs, Cues, Signal Transduction, Cell Division, Transcription, Genetic, Gene Expression Regulation, Plant, Phloem, Cambium
Gatsby Foundation [GAT3395/PR3)] University of Helsinki [award 799992091] ERC Grant SYMDEV [No. 323052] NSF-BBSRC MCSB 1517058 etc.
European Research Council (323052)
Gatsby Charitable Foundation (GAT3395/PR3)
MEDICAL RESEARCH COUNCIL (MR/M008975/1)
External DOI: https://doi.org/10.1038/s41586-018-0839-y
This record's URL: https://www.repository.cam.ac.uk/handle/1810/288837