The Small GTPase OsRac1 Forms Two Distinct Immune Receptor Complexes Containing the PRR OsCERK1 and the NLR Pit

Area of Science:

• Plant immunity
• Molecular plant-pathogen interactions
• Cell biology

Background:

• Plants use pattern recognition receptors (PRRs) and nucleotide-binding leucine-rich repeat proteins (NLRs) for pathogen defense.
• It is unclear if PRRs and NLRs form separate or shared protein complexes.
• The small GTPase OsRac1 is involved in signaling pathways of both PRR OsCERK1 and NLR Pit.

Purpose of the Study:

• To investigate whether PRR OsCERK1 and NLR Pit assemble into the same or distinct protein complexes.
• To elucidate the role of OsRac1 in the formation and function of these immune receptor complexes.
• To understand the involvement of Hsp90 in NLR-mediated immunity.

Main Methods:

• Biochemical assays
• Bioimaging techniques
• Analysis of protein complex formation and localization

Main Results:

• OsRac1 forms two distinct protein complexes, one with OsCERK1 and another with Pit.
• OsCERK1 and Pit use different mechanisms for plasma membrane anchoring.
• OsRac1 activation leads to its recruitment into larger protein complexes upon PRR and NLR activation.
• Hsp90 is crucial for Pit transport to the plasma membrane and its immune function.

Conclusions:

• PRR OsCERK1 and NLR Pit operate through separate OsRac1-containing complexes.
• OsRac1 acts as a central signaling hub orchestrating rice immunity via distinct receptor pathways.
• These findings provide insights into the coordinated regulation of plant immune responses.