# An immune receptor complex evolved in soybean to perceive a polymorphic bacterial flagellin

## TL;DR

Soybean has evolved a unique immune receptor to detect a bacterial flagellin that other plants cannot recognize, offering a way to boost resistance against bacterial wilt disease.

## Contribution

The discovery of polymorphic soybean flagellin receptors that can perceive Ralstonia solanacearum flagellin, enabling enhanced disease resistance in other plants.

## Key findings

- Soybean has evolved receptors that can detect the polymorphic flg22Rso from Ralstonia solanacearum.
- Key residues in soybean receptors are responsible for perceiving flg22Rso, unlike in Arabidopsis.
- Expressing soybean receptors in tomato plants increases resistance to bacterial wilt disease.

## Abstract

In both animals and plants, the perception of bacterial flagella by immune receptors elicits the activation of defence responses. Most plants are able to perceive the highly conserved epitope flg22 from flagellin, the main flagellar protein, from most bacterial species. However, flagellin from Ralstonia solanacearum, the causal agent of the bacterial wilt disease, presents a polymorphic flg22 sequence (flg22Rso) that avoids perception by all plants studied to date. In this work, we show that soybean has developed polymorphic versions of the flg22 receptors that are able to perceive flg22Rso. Furthermore, we identify key residues responsible for both the evasion of perception by flg22Rso in Arabidopsis and the gain of perception by the soybean receptors. Heterologous expression of the soybean flg22 receptors in susceptible plant species, such as tomato, enhances resistance to bacterial wilt disease, demonstrating the potential of these receptors to enhance disease resistance in crop plants.

Ralstonia solanacearum evades plant immunity by producing an atypical flagellin protein, thus causing bacterial wilt disease. Here, Wei et al. show that soybean has evolved a divergent flagellin receptor that recognises R. solanacearum flagellin and enhances wilt resistance when transferred to other plants.