ELIMÄKI Locus Is Required for Vertical Proprioceptive Response in Birch Trees.
Current biology : CB
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Alonso-Serra, J., Shi, X., Peaucelle, A., Rastas, P., Bourdon, M., Immanen, J., Takahashi, J., et al. (2020). ELIMÄKI Locus Is Required for Vertical Proprioceptive Response in Birch Trees.. Current biology : CB, 30 (4), 589-599.e5. https://doi.org/10.1016/j.cub.2019.12.016
Tree architecture has evolved to support a top-heavy above-ground biomass, but this integral feature poses a weight-induced challenge to trunk stability. Maintaining an upright stem is expected to require vertical proprioception through feedback between sensing stem weight and responding with radial growth. Despite its apparent importance, the principle by which plant stems respond to vertical loading forces remains largely unknown. Here, by manipulating the stem weight of downy birch (Betula pubescens) trees, we show that cambial development is modulated systemically along the stem. We carried out a genetic study on the underlying regulation by combining an accelerated birch flowering program with a recessive mutation at the ELIMÄKI locus (EKI), which causes a mechanically defective response to weight stimulus resulting in stem collapse after just three months. We observed delayed wood morphogenesis in eki compared with WT, along with a more mechanically elastic cambial zone and radial compression of xylem cell size, indicating that rapid tissue differentiation is critical for cambial growth under mechanical stress. Furthermore, the touchinduced mechanosensory pathway was transcriptionally misregulated in eki, indicating that the ELIMÄKI locus is required to integrate the weight-growth feedback regulation. By studying this birch mutant, we were able to dissect vertical proprioception from the gravitropic response associated with reaction wood formation. Taken together, our study provides evidence for both local and systemic responses to mechanical stimuli during secondary plant development.
The Academy of Finland Finnish Centre of Excellence in Molecular Biology of Primary Producers (CoE 2014-2019) project (271832) and the project (286404); Gatsby Foundation (GAT3395/PR3); University of Helsinki (award 799992091); European Research Council Advanced Investigator Grant SYMDEV (323052)
European Research Council (323052)
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External DOI: https://doi.org/10.1016/j.cub.2019.12.016
This record's URL: https://www.repository.cam.ac.uk/handle/1810/299680
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Licence URL: https://creativecommons.org/licenses/by-nc-nd/4.0/