Understanding Plant Pathogen Interactions

Oct 28, 2024

Plant Pathogen Interaction

Overview

  • Discussion on plant-pathogen interaction and how pathogens interact with plant cells.

Proteins and Factors in Interaction

  • Plant Cell:
    • PRR (Pattern Recognition Receptors): Located on the plant cell surface.
  • Pathogen:
    • PAMP/MAMP (Pathogen/Microbe Associated Molecular Pattern): Recognized by plant's PRR.
    • Effector Molecules/Pathogen Effectors: Detected by plant cell's R protein.

Plant Immunity Types

  1. ETI (Effector Triggered Immunity): Evoked by pathogen effectors.
  2. PTI (Pattern/PAMP Triggered Immunity): Triggered by PAMP/MAMP.

Plant Pathogen Interaction Details

  • PRR-PAMP Binding:

    • PRR molecules on the plant cell bind to PAMP molecules on the pathogen.
    • Triggers PTI, initiating the MAPK cascade and activation of defense genes.
  • Pathogen Effector Detection:

    • Pathogens secrete effector molecules to hijack plant cells.
    • NBLRR Proteins (Nucleotide-Binding Leucine-Rich Repeat): Detect pathogen effectors and belong to the R protein class.
    • Activation of R genes causes ion flux (efflux of hydroxide, potassium ions, and influx of calcium, hydrogen ions).
    • Results in HR (Hypersensitive Response) leading to oxidative burst, ROS production, and lignin/callos deposition to prevent infection spread.

Short-term and Long-term Responses

  • Hypersensitive Response (HR):
    • Short-term containment of pathogen infection.
    • Induces SAR (Systemic Acquired Resistance), a more advanced immunity.
    • Activates transcription of proteins like phytoalexins and chitinases to degrade fungal cell walls and affect orthopod exoskeletons.

Hormonal Signaling Pathways

  • Different pathways activated based on pathogen type:
    • Necrotrophic Pathogen:
      • Induces JA (Jasmonic Acid) pathway.
    • Biotropic Pathogen:
      • Induces SA (Salicylic Acid) pathway.
  • Activation of these pathways induces PR gene transcription for defense.

Conclusion

  • PR gene expresses PR protein (e.g., chitinases) to combat pathogen infection.
  • Overview of how plant immune systems respond to pathogen encounters.