A RALF-brassinosteroid signaling circuit regulates Arabidopsis hypocotyl cell shape

2025/09/27 by David Biermann, Michelle von Arx, Kristina S. Munzert‐Eberlein +8 · 1 voice · 15 citations
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Arabidopsis #Autocrine signalling #Brassinosteroid #Cell #Cell signaling #Cell type #Plant Molecular Biology Research #Plant Reproductive Biology #Polysaccharides and Plant Cell Walls #Receptor #Signal transduction #Signaling proteins

paper · pdf · doi:10.1016/j.cub.2025.09.016

published in Current Biology 35(20), 5002-5017.e5 (Elsevier BV)

openalex publication_date 2025/09/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22

Abstract

Plant cells survey and modulate their cell walls to control their shape and anisotropic growth. Signaling mediated by the plant steroid hormones brassinosteroids (BR) plays a central role in coordinating cell wall status and cell growth, and alterations in the cell wall-BR feedback loop leads to life-threatening defects in tissue and cellular integrity. How the status of the cell wall is relayed to BR signaling remains largely unclear. Increasing evidence shows that RAPID ALKALANIZATION FACTORs (RALFs), a class of secreted peptides, play structural and signaling roles at the cell surface. Here, we show that loss of RALF signaling mediated by the plasma membrane-localized RALF receptor complex FERONIA (FER)-LORELEI-LIKE GPI-anchor protein 1 (LLG1) leads to defects in cell morphology, organization, and composition of the cell wall-including pectin methylation status-and to an increase in BR signaling. We observed that increase in BR signaling mitigates the cellular defects associated with the loss of FER-mediated RALF signaling. We show that perception of RALF23 promotes the formation and signaling activity of the main BR receptor complex formed by BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE 1 (BAK1) and that its bioactivity relies on pectin status. Our observations suggest a model in which RALF peptides operate at the nexus between cell wall status and BR signaling, capable of inducing changes in the cell wall as well as functioning as a cell-wall-informed signaling cues initiating a feedback loop that solicits BR signaling and coordinates cell morphogenesis.

Citations

• Colorimetric Method for Determination of Sugars and Related Substances
• Brassinosteroid Signaling Network and Regulation of Photomorphogenesis

Cited by

• Plasma membrane nanoscale dynamics of Arabidopsis leucine-rich repeat receptor kinase complexes
• An ancient alkalinization factor informs Arabidopsis root development
• Peptide signaling at the intersection of growth, nutrient sensing, and stress responses
• The interplay of RALF structural and signaling functions in plant-microbe interactions. [europepmc]
• Plant cell wall remodeling and peptide signaling under abiotic and biotic stress. [europepmc]
• Peptide signaling at the intersection of growth, nutrient sensing, and stress responses. [europepmc]

Discussions

• A RALF-brassinosteroid signaling circuit regulates Arabidopsis hypocotyl cell shape doi.org/10.1016/j.cu... [bsky, 16 points, 1 comments]

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