The Arabidopsis miR396 mediates pathogen-associated molecular pattern-triggered immune responses against fungal
Mauricio Soto-Suárez1, Patricia Baldrich1, Detlef Weigel2
1Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB. Edifici CRAG, Campus UAB, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain.
Abstract:
MicroRNAs (miRNAs) play a pivotal role in regulating gene expression during plant development. Although a substantial fraction of plant miRNAs has proven responsive to pathogen infection, their role in disease resistance remains largely unknown, especially during fungal infections. In this study, we screened Arabidopsis thaliana lines in which miRNA activity has been reduced using artificial miRNA target mimics (MIM lines) for their response to fungal pathogens. Reduced activity of miR396 (MIM396 plants) was found to confer broad resistance to necrotrophic and hemibiotrophic fungal pathogens. MiR396 levels gradually decreased during fungal infection, thus, enabling its GRF (GROWTH-REGULATING FACTOR) transcription factor target genes to trigger host reprogramming. Pathogen resistance in MIM396 plants is based on a superactivation of defense responses consistent with a priming event during pathogen infection. Notably, low levels of miR396 are not translated in developmental defects in absence of pathogen challenge. Our findings support a role of miR396 in regulating plant immunity, and broaden our knowledge about the molecular players and processes that sustain defense priming. That miR396 modulates innate immunity without growth costs also suggests fine-tuning of miR396 levels as an effective biotechnological means for protection against pathogen infection.
Insights
Reduced microRNA (miRNA) activity, specifically miR396, enhances plant immunity against fungal pathogens without causing developmental issues. This discovery offers a new strategy for disease resistance in crops.
Area of Science:
- Plant Molecular Biology
- Plant Pathology
- Genetics
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression in plants.
- While some plant miRNAs respond to pathogens, their role in fungal disease resistance is poorly understood.
- Understanding miRNA function is crucial for developing novel disease resistance strategies.
Purpose of the Study:
- To investigate the role of specific miRNAs in plant defense against fungal pathogens.
- To screen Arabidopsis thaliana lines with reduced miRNA activity for enhanced disease resistance.
- To elucidate the molecular mechanisms underlying miR396-mediated plant immunity.
Main Methods:
- Screening of Arabidopsis thaliana artificial miRNA target mimic (MIM) lines.
- Assessing disease resistance in MIM396 plants against necrotrophic and hemibiotrophic fungal pathogens.
- Analyzing miR396 levels and its target gene (GROWTH-REGULATING FACTOR transcription factors) expression during infection.
Main Results:
- Reduced miR396 activity (MIM396 plants) conferred broad resistance to fungal pathogens.
- miR396 levels decreased during infection, allowing GRF transcription factors to reprogram host responses.
- MIM396 plants exhibited superactivated defense responses, indicating a priming effect.
- Low miR396 levels did not cause developmental defects in the absence of pathogens.
Conclusions:
- miR396 plays a significant role in regulating plant innate immunity and defense priming.
- Modulating miR396 levels enhances pathogen resistance without compromising plant growth.
- Fine-tuning miR396 offers a potential biotechnological approach for crop protection against fungal infections.
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