1. A Reservoir of Pluripotent Phloem Cells Safeguards the Linear Developmental Trajectory of Protophloem Sieve Elements.
- Author
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Gujas, Bojan, Kastanaki, Elizabeth, Sturchler, Alessandra, Cruz, Tiago M.D., Ruiz-Sola, M. Aguila, Dreos, Rene, Eicke, Simona, Truernit, Elisabeth, and Rodriguez-Villalon, Antia
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SIEVE elements , *PHLOEM , *RESERVOIRS , *PROTEIN kinases , *MULTICELLULAR organisms - Abstract
Plant cells can change their identity based on positional information, a mechanism that confers developmental plasticity to plants. This ability, common to distinct multicellular organisms, is particularly relevant for plant phloem cells. Protophloem sieve elements (PSEs), one type of phloem conductive cells, act as the main organizers of the phloem pole, which comprises four distinct cell files organized in a conserved pattern. Here, we report how Arabidopsis roots generate a reservoir of meristematic phloem cells competent to swap their cell identities. Although PSE misspecification induces cell identity hybridism, the activity of RECEPTOR LIKE PROTEIN KINASE 2 (RPK2) by perceiving CLE45 peptide contributes to restrict PSE identity to the PSE position. By maintaining a spatiotemporal window when PSE and PSE-adjacent cells' identities are interchangeable, CLE45 signaling endows phloem cells with the competence to re-pattern a functional phloem pole when protophloem fails to form. • An early PSE misspecification promotes identity hybridism between PSE and CC • Meristematic CC and MSE retain plastic identity to safeguard phloem functionality • RPK2 excludes PSE identity from PSE-surrounding cells within the root meristem • CLE45 maintains PSE and PSE-surrounding cells in a plastic identity stage Gujas et al. describe a molecular mechanism that endows plant cells with a plastic cell fate. Hereby, CLE-RPK2 module halts heterogeneous phloem cells sub-specification. This plastic identity state safeguards the re-establishment of a functional phloem pattern in case conductive protophloem fails to form in its by-lineage-predestined position. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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