Screening and Validation of Interacting Proteins of Receptor-like Cytoplasmic Kinase OsRLCK118 Involved in Rice Blast Resistance

TL;DR

This study identifies proteins that interact with OsRLCK118, a kinase involved in rice immunity, revealing a new signaling pathway that could help improve rice blast resistance.

Contribution

The study discovers a novel signaling axis involving OsRLCK118 and OsSAMS1 in rice immunity against blast disease.

Findings

OsRLCK118 physically interacts with OsSAMS1, a known positive regulator of blast resistance.

OsRLCK118 specifically phosphorylates OsSAMS1 in vitro, linking pathogen recognition to ethylene biosynthesis.

The interaction between OsRLCK118 and OsSAMS1 provides mechanistic insight into rice immunity.

Abstract

Rice blast, caused by Magnaporthe oryzae, severely threatens global rice production. Although the receptor-like cytoplasmic kinase OsRLCK118 positively regulates rice immunity, its downstream signaling mechanism remains unknown. To systematically identify OsRLCK118-interacting proteins, we performed immunoprecipitation–mass spectrometry (IP-MS) and a yeast library screen, yielding 781 and 287 candidates, respectively, with 35 overlapping hits. Among these, OsSAMS1, a known positive regulator of blast resistance, was selected for validation. Membrane yeast two-hybrid, split-luciferase complementation, and co-immunoprecipitation assays confirmed the physical interaction between OsRLCK118 and OsSAMS1. Furthermore, in vitro kinase assays showed that OsRLCK118 specifically phosphorylates OsSAMS1. These results uncover a novel signaling axis connecting pathogen recognition to ethylene biosynthesis via OsRLCK118-dependent phosphorylation of OsSAMS1, providing both mechanistic insight into rice immunity and potential genetic targets for resistance breeding.

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