NPR1-Mediated Plant Immunity Mechanisms

NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) is a central regulator of salicylic acid (SA)–induced plant defence, acting both as an SA receptor and as a transcriptional co-activator. In resting cells NPR1 resides in the cytosol as an oligomer maintained by redox-sensitive disulfide bonds. On pathogen challenge SA accumulation triggers a shift in cellular redox state, promoting reduction of NPR1 to monomers that translocate into the nucleus. There, NPR1 assembles into biomolecular condensates and associates with TGACG‐binding (TGA) transcription factors and other chromatin modifiers to orchestrate a transcriptional cascade. Initial binding to primary target promoters induces secondary regulators, notably WRKY factors, which then activate a broad suite of defence genes, including pathogenesis-related proteins and components of systemic acquired resistance (SAR). NPR1 activity is finely tuned by post-translational modifications such as phosphorylation, ubiquitination and acetylation, ensuring dynamic control of immune outputs. Beyond Arabidopsis, NPR1 homologues in crop species integrate crosstalk with jasmonic acid and other hormones, underpinning both local and systemic immunity. Insights into NPR1 function have informed strategies for engineering disease-resistant varieties, highlighting its global significance for sustainable agriculture.

Research from Nature Portfolio

Recent studies in monocot rice have revealed how viral effectors undermine NPR1-mediated antiviral immunity. The P2 protein of rice stripe virus enhances association of OsNPR1 with the E3 ligase adaptor OsCUL3a, promoting degradation of OsNPR1 and disrupting its role in coordinating salicylic acid–jasmonic acid synergy. OsNPR1 normally activates jasmonic acid signalling by dismantling the OsJAZ–OsMYC repressor complex and enhancing OsMYC2 transcriptional activity to bolster antiviral defences. Unrelated viral proteins converge on this mechanism to suppress SA–JA crosstalk, illustrating a common strategy by which pathogens impair NPR1 function and compromise broad-spectrum immunity in monocots.

NPR1-Mediated Plant Immunity Mechanisms publication trend

The graph below shows the total number of articles in npr1-mediated plant immunity mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

NPR1: Master regulator of SA-dependent immunity, acting as both receptor and transcriptional co-activator.

Salicylic acid (SA): Phytohormone that triggers local and systemic defence responses against pathogens.

Systemic acquired resistance (SAR): Long‐lasting, broad‐spectrum immunity induced throughout the plant following localized infection.

Biomolecular condensates: Membrane-less organelles formed by phase separation that concentrate proteins and nucleic acids to facilitate signalling and transcription.

TGACG-binding (TGA) factors: Family of bZIP transcription factors that recruit NPR1 to specific promoter motifs to activate defence genes.

Histone acetylation: Epigenetic modification that relaxes chromatin structure and promotes gene transcription during immune activation.

References

1. Next-generation mapping of the salicylic acid signaling hub and transcriptional cascade. Molecular Plant (2024).
2. Different viral effectors suppress hormone-mediated antiviral immunity of rice coordinated by OsNPR1. Nature Communications (2023).
3. Genomic overview of INA-induced NPR1 targeting and transcriptional cascades in Arabidopsis. Nucleic Acids Research (2024).
4. Salicylic acid-induced transcriptional reprogramming by the HAC–NPR1–TGA histone acetyltransferase complex in Arabidopsis. Nucleic Acids Research (2018).
5. The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) and Related Family: Mechanistic Insights in Plant Disease Resistance. Frontiers in Plant Science (2019).
6. Posttranslational Modifications of NPR1: A Single Protein Playing Multiple Roles in Plant Immunity and Physiology. PLOS Pathogens (2016).
7. The Arabidopsis NPR1 Protein Is a Receptor for the Plant Defense Hormone Salicylic Acid. Cell Reports (2012).
8. Overexpression of NPR1 in Brassica juncea Confers Broad Spectrum Resistance to Fungal Pathogens. Frontiers in Plant Science (2017).