Sphingolipid remodeling in the plasma membrane is essential for osmotic stress tolerance in Arabidopsis.

This article investigates the role of glucosylceramidases GCD1 and GCD3 in sphingolipid remodeling of the plasma membrane (PM) and their importance for osmotic stress tolerance in Arabidopsis thaliana. The study demonstrates that GCD1, localized to the PM, hydrolyzes glucosylceramides (GlcCers) to ceramides, altering membrane lipid composition by decreasing GlcCer and increasing glycosylinositol phosphoceramide (GIPC) levels, which modulates membrane order and tension under osmotic stress. Loss of both GCD1 and GCD3 disrupts sphingolipid homeostasis, impairs osmotic stress–induced gene expression and root growth, and increases membrane sensitivity to osmotic changes. Additionally, the gcd1 gcd3 double mutant exhibits enhanced resistance to the herbivore Spodoptera exigua, associated with elevated jasmonate signaling, suggesting that sphingolipid metabolism via GCD1 and GCD3 influences both abiotic stress tolerance and biotic defense responses by regulating PM physicochemical properties.