Diverse phytocytokines derived from conserved subtilase scaffolds co-evolved with clustered receptors to confer defence responses in legumes

Abstract

Plant peptide hormones orchestrate growth, development and immunity by engaging membrane-resident receptor kinases. GmSubPEP, a defence-eliciting peptide derived from a subtilase precursor, was initially isolated from soybean leaf extracts. Here we uncover an unexpected expansion of GmSubPEP variants with highly diverse sequences, yet each capable of triggering robust, tissue-specific pathogen resistance. Integrated transcriptomic and phosphoproteomic profiling shows that individual GmSubPEPs differentially activate overlapping and unique immune pathways, enabling fine-tuned defence modulation. Strikingly, genes generating these peptides and their receptors, termed GmSubPEP Receptors (GSPRs), are physically interspersed within a genomic cluster, and GSPRs exhibit differential binding affinities for their cognate peptide ligands. By unveiling how conserved subtilase precursor scaffolds diversify into specialized ligand–receptor pairs across legume lineages, our work reveals the role of SubPEP–GSPR modules in plant–microbe interactions and provides a framework for mining and engineering peptide–receptor modules to strengthen crop immunity. This study identifies SubPEP variants in soybean that confer tissue-specific immunity via GmSubPEP Receptors. Their precursor genes and receptor genes are colocalized in genomic clusters, revealing the diversification of conserved ligand–receptor pairs for crop immunity.