Identification of endogenous small peptides involved in rice immunity through transcriptomics- and proteomics-based...

Area of Science:

• Plant Molecular Biology
• Plant Immunity
• Peptide Signaling

Background:

• Small signaling peptides regulate crucial plant processes like development and immunity.
• The specific small signaling peptides involved in plant immunity are largely unidentified.
• Rice blast fungus (Magnaporthe oryzae) and chitin are key factors in rice immunity.

Purpose of the Study:

• To develop a pipeline for identifying precursors of small signaling peptides in rice.
• To discover small secreted proteins (SSPs) in rice induced by Magnaporthe oryzae and chitin.
• To identify novel peptide precursors involved in regulating rice immunity.

Main Methods:

• Developed a screening pipeline integrating transcriptomics and proteomics data.
• Identified small secreted proteins (SSPs) in rice induced by rice blast fungus and chitin.
• Analyzed gene expression and protein levels of identified SSPs, including the novel IRP gene.

Main Results:

• Identified 236 SSPs, including known families (e.g., rapid alkalinization factors, phytosulfokines) and immunity-related proteins.
• Discovered 52 unannotated SSPs, including the novel immune response peptide (IRP) gene.
• IRP expression was induced by bacterial peptidoglycan and fungal chitin; its overexpression enhanced defense gene PAL1 and activated MAPKs. IRP protein levels increased in medium after chitin treatment.

Conclusions:

• Established an efficient pipeline for discovering SSP candidates involved in plant immunity.
• Identified novel SSPs, including IRP, that play a role in regulating rice immunity.
• The developed method is applicable for identifying SSPs in various plant functions beyond immunity.