Endoplasmic Reticulum Stress Responses in Plant Systems

The endoplasmic reticulum (ER) is the central organelle for protein synthesis and folding in plant cells, maintaining cellular homeostasis by ensuring that secretory and membrane proteins attain their correct conformation. Adverse environmental conditions such as heat, salinity or pathogen attack can overwhelm ER folding capacity, leading to accumulation of misfolded proteins and activation of the unfolded protein response (UPR). In plants, two principal UPR signalling arms emanate from membrane-embedded sensors: proteolytic activation of membrane-associated basic leucine zipper (bZIP) transcription factors and unconventional mRNA splicing catalysed by the ER-resident inositol-requiring enzyme 1 (IRE1). Together, these pathways induce expression of chaperones and quality-control factors, restore ER function and adjust secretory load. If stress persists, pro-death programmes engage, culminating in programmed cell death to protect the organism from chronic damage. The UPR intersects with heat shock and immune signalling, modulating development, reproductive success and defence. Understanding ER stress responses in plants underpins strategies for enhancing crop resilience and optimising plant platforms for recombinant protein production in biotechnology.

Research from Nature Portfolio

Recent studies in Arabidopsis have elucidated a critical node in UPR-mediated cell fate determination, revealing that the programmed cell death regulator BAP2 modulates the amplitude of IRE1-driven responses. Natural variation analyses and quantitative trait mapping identified a single nucleotide polymorphism that abolishes BAP2 function, altering the balance between adaptive UPR and activation of cell death. The work demonstrates that ER stress-induced BAP2 expression is antagonistically controlled by IRE1 and that BAP2 governs the threshold at which unresolved stress triggers pro-death signals. These insights refine our understanding of how plants negotiate survival and demise under persistent ER stress.

Endoplasmic Reticulum Stress Responses in Plant Systems publication trend

The graph below shows the total number of articles in endoplasmic reticulum stress responses in plant systems across all publications each year (not limited to Nature Index journals).

Technical terms

Unfolded protein response (UPR): A network of signalling pathways that detect and mitigate the accumulation of misfolded proteins in the endoplasmic reticulum, aiming to restore homeostasis or initiate cell death if stress remains unresolved.

Inositol-requiring enzyme 1 (IRE1): An ER-localised sensor and endoribonuclease that activates one branch of the UPR by catalysing unconventional splicing of specific mRNAs, notably those encoding bZIP transcription factors.

Programmed cell death (PCD): A genetically controlled process leading to organised cellular demise, engaged when adaptive responses fail to relieve severe or prolonged ER stress.

Basic leucine zipper (bZIP) transcription factors: Proteins characterised by a basic DNA-binding region and leucine zipper motif, which upon activation relocate to the nucleus to drive transcription of UPR and stress-responsive genes.

References

1. Programmed cell death regulator BAP2 is required for IRE1-mediated unfolded protein response in Arabidopsis. Nature Communications (2024).
2. Heterologous expression of influenza haemagglutinin leads to early and transient activation of the unfolded protein response in Nicotiana benthamiana. Plant Biotechnology Journal (2023).
3. A membrane‐associated NAC transcription factor OsNTL3 is involved in thermotolerance in rice. Plant Biotechnology Journal (2019).
4. IRE1/bZIP60-Mediated Unfolded Protein Response Plays Distinct Roles in Plant Immunity and Abiotic Stress Responses. PLOS ONE (2012).