USP1, an MAPK Target with Chaperone-like Activity, Regulates Innate Plant Immunity in Arabidopsis
Year: 2026
Type: article
Abstract: In eukaryotes, mitogen-activated protein kinase (MAPK) cascades are highly conserved signaling modules in transducing extracellular signals perceived by receptors/sensors. MAPKs phosphorylate cytoplasmic and nuclear target proteins, modifying their stability, protein–protein interaction, enzyme activity, DNA-binding affinity, and subcellular localization. A comparative phosphoproteomics analysis of wild-type and mapk mutant plants identified a previously uncharacterized protein, USP1, as a novel MAPK target. In this work, we investigated the role of USP1 in pathogen responses. CRISPR-Cas9-generated knockout usp1 mutants displayed enhanced resistance to the bacterial pathogen P. syringae pv. tomato DC3000, reduced apoplast reactive oxygen species (ROS) accumulation, and upregulated defense marker genes such as WRKY29 and FRK1. Transcriptome analyses revealed that immune hormone signaling genes, such as salicylic acid (SA) and jasmonic acid (JA), are differentially regulated. These hormones are responsible for primary defense responses against biotrophic and necrotrophic pathogens, respectively. Accordingly, usp1 mutants show enhanced and reduced resistance to bacterial and fungal infection by Pst DC3000 and Botrytis cinerea, respectively. Biochemical analyses showed that USP1 exhibits chaperone-like activity that stabilizes various proteins, including the MAPKs MPK4 and MPK6. Furthermore, usp1 mutants were defective in flg22-mediated immune priming, indicating that USP1 is required for the establishment of PAMP-induced immune memory. Collectively, our findings identify USP1 as a MAPK-regulated chaperone that plays an important role in coordinating plant immune responses.
DOI: 10.3390/ijms27219426
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $3,499
OpenAlex ID: W7223281675