The <i>Arabidopsis</i> Receptor Kinase FLS2 Binds flg22 and Determines the Specificity of Flagellin Perception

TLDR

Flagellin is a pathogen‑associated molecular pattern that triggers innate immunity, and in Arabidopsis thaliana the Leu‑rich repeat receptor kinase FLS2 is essential for flagellin perception. The study aims to demonstrate the specific interaction between the elicitor‑active epitope flg22 and the FLS2 protein. Chemical cross‑linking and immunoprecipitation were used to show flg22 binding to FLS2, and heterologous expression of the Arabidopsis FLS2 gene in tomato cells tested receptor functionality. Expression of Arabidopsis FLS2 in tomato cells conferred a flg22‑perception system with Arabidopsis‑like properties, proving that FLS2 determines the specificity of flagellin perception.

Abstract

Abstract Flagellin, the main building block of the bacterial flagellum, acts as a pathogen-associated molecular pattern triggering the innate immune response in animals and plants. In Arabidopsis thaliana, the Leu-rich repeat transmembrane receptor kinase FLAGELLIN SENSITIVE2 (FLS2) is essential for flagellin perception. Here, we demonstrate the specific interaction of the elicitor-active epitope flg22 with the FLS2 protein by chemical cross-linking and immunoprecipitation. The functionality of this receptor was further tested by heterologous expression of the Arabidopsis FLS2 gene in tomato (Lycopersicon esculentum) cells. The perception of flg22 in tomato differs characteristically from that in Arabidopsis. Expression of Arabidopsis FLS2 conferred an additional flg22-perception system on the cells of tomato, which showed all of the properties characteristic of the perception of this elicitor in Arabidopsis. In summary, these results show that FLS2 constitutes the pattern-recognition receptor that determines the specificity of flagellin perception.