Leucine-rich repeat receptor-like gene screen reveals that Nicotiana RXEG1 regulates glycoside hydrolase 12 MAMP detection

Yan Wang,Jiaming Qi,Yuanchao Wang,Wenwu Ye,Suomeng Dong,Yachun Lin,Yuanpeng Xu,Brett M Tyler,Bowen Wan,Yuanyuan Shao,Huibin Wang,Yujing Sun

doi:10.1038/s41467-018-03010-8

Abstract

Activation of innate immunity by membrane-localized receptors is conserved across eukaryotes. Plant genomes contain hundreds of such receptor-like genes and those encoding proteins with an extracellular leucine-rich repeat (LRR) domain represent the largest family. Here, we develop a high-throughput approach to study LRR receptor-like genes on a genome-wide scale. In total, 257 tobacco rattle virus-based constructs are generated to target 386 of the 403 identified LRR receptor-like genes in Nicotiana benthamiana for silencing. Using this toolkit, we identify the LRR receptor-like protein Response to XEG1 (RXEG1) that specifically recognizes the glycoside hydrolase 12 protein XEG1. RXEG1 associates with XEG1 via the LRR domain in the apoplast and forms a complex with the LRR receptor-like kinases BAK1 and SOBIR1 to transduce the XEG1-induced defense signal. Thus, this genome-wide silencing assay is demonstrated to be an efficient toolkit to pinpoint new immune receptors, which will contribute to developing durable disease resistance.

Highlights

Activation of innate immunity by membrane-localized receptors is conserved across eukaryotes
We successfully identify the Response to XEG1 (RXEG1) protein, which is required for response to the glycoside hydrolase 12 (GH12) protein XEG1 and homologs in N. benthamiana
We scanned the genome of N. benthamiana using both BLAST and hidden Markov model (HMM) searches to identify fragments encoding proteins with both leucine-rich repeat (LRR) and TM domains

Summary

Introduction

Activation of innate immunity by membrane-localized receptors is conserved across eukaryotes. RXEG1 associates with XEG1 via the LRR domain in the apoplast and forms a complex with the LRR receptor-like kinases BAK1 and SOBIR1 to transduce the XEG1-induced defense signal This genome-wide silencing assay is demonstrated to be an efficient toolkit to pinpoint new immune receptors, which will contribute to developing durable disease resistance. Only a few LRR receptor-like genes have been documented encoding PRRs capable of recognizing MAMPs or receptor-like proteins (DAMPs) and function as immune receptors[12] These include RLKs, such as the bacterial flagellin receptors FLS213,14 and FLS315, the bacterial elongation factor Tu receptor EFR, the bacterial elicitor xup[25] receptor XPS1, and the DAMP receptors PEPR1 and PEPR216–19. The GH12 proteins are widely distributed across microbial taxa and many are able to trigger cell death in plants[34,36], indicating that the recognition system is evolutionally conserved

Methods

Results

Conclusion