The EDS1-PAD4-ADR1 node mediates Arabidopsis pattern-triggered immunity.

Area of Science:

• Plant immunity
• Molecular plant-microbe interactions
• Signal transduction

Background:

• Plants utilize cell-surface and intracellular leucine-rich repeat (LRR) immune receptors to detect pathogens.
• Pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) are initiated in different cellular compartments but converge on similar gene expression patterns.

Purpose of the Study:

• To investigate the molecular mechanisms underlying PTI and ETI pathway convergence in Arabidopsis.
• To identify key signaling components shared between PTI and ETI.

Main Methods:

• Investigated the role of EDS1, PAD4, and ADR1 in RLP23-triggered PTI.
• Utilized genetic and molecular approaches to study protein interactions and signaling complex formation.
• Analyzed evolutionary patterns of LRR receptor genes in Arabidopsis accessions.

Main Results:

• PTI triggered by RLP23 requires signaling-competent dimers of EDS1, PAD4, and ADR1, components typically associated with ETI.
• The LRR receptor kinase SOBIR1 acts as a bridge, linking RLP23 to EDS1, PAD4, and ADR1.
• Supramolecular complexes involving PTI receptors and ETI transducers form at the plasma membrane.
• Evolutionary analysis reveals distinct variation patterns in LRR receptor protein and LRR receptor kinase genes, suggesting specialized roles.

Conclusions:

• The EDS1-PAD4-ADR1 node serves as a crucial convergence point for plant defense signaling.
• Both surface-resident (PTI) and intracellular (ETI) LRR receptors activate this common node to confer pathogen immunity.
• This finding advances our understanding of the integrated nature of plant immune signaling pathways.