Related Experiment Video
Updated: May 19, 2026

Identification of Post-translational Modifications of Plant Protein Complexes
Published on: February 22, 2014
Linking sugar sensing to immunity in plants through O-glycosylation of immune-signaling kinases
Yalikunjiang Aizezi1,2,3, Yang Bi1,3, Hongliang Zhang1,3
1Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA.
Abstract:
Interaction with microbes can reprogram metabolism and alter nutrient availability in plant cells. How metabolic changes modulate immune responses remains unknown. Here, we show that sugar-sensing O-glycosylation of immune-signaling kinases mediates metabolic regulation of immunity. Under sugar-replete conditions, the MAP kinase kinases (MKK4 and MKK5), key components of pattern-triggered immunity (PTI), are glycosylated with O-GlcNAc and O-fucose on their activation loops, blocking their phosphorylation by upstream kinases and thereby restricting PTI. Pathogen infection or sugar starvation reduces O-glycosylation of MKK4/5 and enhances immune signaling; these effects are reversed by GDP-fucose treatment, demonstrating that reduced sugar availability decreases O-fucosylation and enhances immune signaling in infected cells. Chemical inhibition of O-fucosylation enhances immunity and pathogen resistance in both Arabidopsis and tomato. Our findings establish O-glycosylation of MKKs as a metabolic rheostat that fine-tunes immune responses according to sugar availability during plant-microbe interactions, providing a new strategy for improving crop health.
Related Concept Videos
Oligosaccharide Assembly
Multiple sugar molecules that may or may...
Protein Glycosylation
Glycosylation occurs in...
Proteoglycans
Cell Signaling in Plants
Biosynthesis of Polysaccharides
Protein Modifications in the RER
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.

