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Poster

Session: Session 2 Presenting Authors at Posters (Odds)

P-405 - DDI1 - A novel regulator of biotic and abiotic proteotoxic stress responses in plants

Wednesday, July 16, 2025
13:30 - 15:15  
Location: Confex Hall 3
Plant Regulation of biotic and abiotic stress – trade-offs

    Presenting Author(s)

  • MR

    Margot Raffeiner

    Ruhr University Bochum
    Bochum, Nordrhein-Westfalen, Germany

    • Author(s)

  • GL

    Gautier Langin

    Faculty of Biology and Biotechnology, Ruhr-University of Bochum
    Bochum, Nordrhein-Westfalen, Germany

  • HT

    Huang Tan

    Department of Plant Biochemistry, Centre for Plant Molecular Biology (ZMBP), Eberhard Karls University
    Tubingen, Baden-Wurttemberg, Germany

  • MF

    Mirita Franz-Wachtel

    Proteome Center Tübingen, University of Tübingen
    Tübingen, Baden-Wurttemberg, Germany

  • BM

    Boris Macek

    Proteome Center Tübingen, University of Tübingen
    Tübingen, Baden-Wurttemberg, Germany

  • RL

    Rosa Lozano-Durán

    University of Tü​bingen
    Tübingen, GERMANY

  • SU

    Suayib Uestuen

    Ruhr-University Bochum
    Bochum, Nordrhein-Westfalen, Germany

Proteotoxic stress, caused by the accumulation of misfolded or excess proteins, threatens cell survival. Eukaryotic cells counter this through protein degradation pathways like the ubiquitin-26S proteasome system (UPS), which is crucial for cellular homeostasis and stress responses. In plants, UPS activity increases during bacterial infections, while pathogens suppress it to enhance virulence. Proteasome activation regulates growth and energy balance in plants. While pathogens manipulate the proteasome, plants may have evolved this interaction as a defense strategy, leveraging the growth-defense trade-off to counter infections.
Here, we identify Arabidopsis DNA-DAMAGE INDUCIBLE 1 (DDI1), a ubiquitin-binding aspartyl protease, as a key regulator of proteotoxic stress and immunity. ddi1 mutants are highly sensitive to proteasome inhibition (e.g., induced by bortezomib) and Pseudomonas syringae pv. tomato (Pst) stress, showing reduced proteasome gene expression, increased ubiquitinated protein accumulation, and enhanced Pst susceptibility. We show that DDI1 cleaves NAC53 and NAC78, transcription factors that activate proteasome genes, promoting their nuclear translocation. Evidence suggests DDI1 also regulates abiotic stress, balancing heat stress and bacterial defense. TurboID proximity labeling supports DDI1’s role in protein degradation pathways during biotic and abiotic stress. Overall, DDI1 links protein degradation, stress adaptation, and plant immunity.