FERONIA rmaintains cell-wall integrity during salt stress through Ca2+ signaling (Curr. Biol.)

Growing plant cells need to loosen up their cell walls while maintaining their integrity. This process gets trickier when plants are exposed to salt stress. Feng et al. describe the important role of the plasma membrane-localized receptor-like kinase FERONIA in restoring growth and cell wall integrity after exposure to salinity. FERONIA mutants showed high rate of cell rupture in root cortex and epidermal cells, most probably due to inability to restore cell wall rigidity after exposure to salinity. Salt stress induces cell wall loosening as sodium ions replace load-bearing ionic interactions in the pectin matrix, which are facilitated by calcium and boron ions. Although FERONIA’s extracellular domains were found to bind pectin in vitro, its role in sensing cell wall rigidity remains to be determined. FERONIA is also involved in eliciting a transient increase in calcium that coincides with growth recovery. The work explores the concept of salt toxicity occurring at the apoplast during the very early phase of salt stress exposure. (Summary by Magdalena Julkowska) Current Biology 10.1016/j.cub.2018.01.023