receptor-like protein mediates the response to pectin modification by activating brassinosteroid signaling

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 42; pp. 15261 - 15266
• Main Authors: Wolf, Sebastian, van der Does, Dieuwertje, Ladwig, Friederike, Sticht, Carsten, Kolbeck, Andreas, Schürholz, Ann-Kathrin, Augustin, Sebastian, Keinath, Nana, Rausch, Thomas, Greiner, Steffen, Schumacher, Karin, Harter, Klaus, Zipfel, Cyril, Höfte, Herman
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 21.10.2014; National Acad Sciences
• Subjects: Arabidopsis Proteins - physiology; Biological Sciences; biosynthesis; Brassinosteroids; Brassinosteroids - chemistry; Cell growth; Cell Wall - metabolism; Cell walls; Cells; Cloning, Molecular; Gene expression; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant; genes; growth and development; Homeostasis; Life Sciences; Ligands; Microscopy, Confocal; monitoring; Mutation; pectins; Pectins - chemistry; Phenotype; Phenotypes; Plant cells; Plant growth; Plant growth regulators; Plant Proteins - physiology; Plants; Protein Binding; Protein Interaction Mapping; Protein-Serine-Threonine Kinases - physiology; Proteins; Receptors; Signal Transduction; brassinosteroids; cell wall integrity; pectin
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1322979111

The brassinosteroid (BR) signaling module is a central regulator of plant morphogenesis, as indicated by the large number of BR-responsive cell wall-related genes and the severe growth defects of BR mutants. Despite a detailed knowledge of the signaling components, the logic of this auto-/paracrine signaling module in growth control remains poorly understood. Recently, extensive cross-talk with other signaling pathways has been shown, suggesting that the outputs of BR signaling, such as gene-expression changes, are subject to complex control mechanisms. We previously provided evidence for a role of BR signaling in a feedback loop controlling the integrity of the cell wall. Here, we identify the first dedicated component of this feedback loop: a receptor-like protein (RLP44), which is essential for the compensatory triggering of BR signaling upon inhibition of pectin de-methylesterification in the cell wall. RLP44 is required for normal growth and stress responses and connects with the BR signaling pathway, presumably through a direct interaction with the regulatory receptor-like kinase BAK1. These findings corroborate a role for BR in controlling the sensitivity of a feedback signaling module involved in maintaining the physico-chemical homeostasis of the cell wall during cell expansion. Significance Plant growth and development depend on the biosynthesis and remodeling of the cell wall. To coordinate these two processes, surveillance mechanisms have evolved to monitor the state of the cell wall. The brassinosteroid (BR) hormone signaling pathway plays an essential role in growth control and regulates the expression of a plethora of cell wall-related genes. We have previously shown that feedback signaling from the wall can modulate the outputs of the BR pathway, ensuring cell wall homeostasis and integrity. Here, we identified a receptor-like protein (RLP44), which mediates the activation of BR signaling through direct interaction with the BR coreceptor BAK1. Thus, RLP44 integrates cell wall surveillance with hormone signaling to control cell wall integrity and growth.