Allelic variation of an LRR only protein confers dual pathogen resistance in Arabidopsis

Plants utilize versatile leucine-rich repeat (LRR) proteins to perceive diverse pathogen-derived signals, thereby activating or suppressing defense responses. However, the specific roles of LRR-only proteins in pathogen-specific resistance remain largely unclear. Here, we show that allelic variations in an Arabidopsis thaliana LRR-only gene, LEUCINE-RICH REPEAT IMMUNE PROTEIN 1 (LRIP1), underlies dual functions in combating distinct pathogens. An allele common in arid regions confers resistance to Pseudomonas syringae pv. tomato (Pst) bacteria via salicylic acid (SA) signaling pathway, whereas an allele enriched in high-precipitation regions protects against Botrytis cinerea fungus via camalexin biosynthesis. Divergence in promoter and coding sequences between the two alleles modulates gene expression and elicitor-associated immune responses, thereby promoting pathogen-specific complex formation with BRASSINOSTEROID INSENSITIVE 1 (BRI1)-ASSOCIATED RECEPTOR KINASE 1 (BAK1). Globally distributed A. thaliana accessions carry two distinct LRIP1 allele groups that correlate with local precipitation conditions. These findings demonstrate that a single LRR-only gene can evolve environmentally adapted alleles that optimize immunity against different pathogens in contrasting habitats.