Genotyping-by-sequencing-based identification of Arabidopsis pattern recognition receptor RLP32 recognizing proteobacterial translation initiation factor IF1

Abstract

Pattern-triggered immunity (PTI) is a central component of plant immunity. Activation of PTI relies on the recognition of microbe-derived structures, termed patterns, through plant encoded surface-resident pattern recognition receptors (PRRs). We have identified proteobacterial translation initiation factor 1 (IF1) as an immunogenic pattern that triggers PTI in Arabidopsis thaliana and some related Brassicaceae species. Unlike most other immunogenic patterns identified, IF1 elicitor activity cannot be assigned to a small peptide epitope, suggesting that tertiary fold features are required for IF1 receptor activation. We have deployed natural variation in IF1 sensitivity to identify leucine-rich repeat (LRR) receptor-like protein 32 (RLP32) as the corresponding Arabidopsis receptor using a restriction site-associated DNA sequencing (RAD-seq) approach. Transgenic expression of RLP32 confers IF1 sensitivity to rlp32 mutants, IF1-insensitive Arabidopsis accessions and IF1-insensitive Nicotiana benthamiana. RLP32 binds IF1 specifically and forms complexes with LRR receptor kinases SOBIR1 and BAK1 to mediate signaling. Similar to previously identified PRRs RLP32 confers resistance to Pseudomonas syringae infection, highlighting an unexpectedly complex array of bacterial pattern sensors within a single plant species.

The N‐terminus of a Fusarium graminearum‐secreted protein enhances broad‐spectrum disease resistance in plants

“…For example, the 22‐amino‐acid peptide flg22 from bacterial flagellin is a classical PAMP and is sensed by flagellin‐sensing 2 (FLS2) to stimulate cellular responses such as an oxidative burst and the transcriptional induction of downstream genes (Chinchilla et al, 2007; Denoux et al, 2008). Translation initiation factor 1 (IF1) isolated from Ralstonia solanacearum was recently demonstrated to bind to an RLP32 receptor, which recognizes the tertiary fold features of IF1 and induces PTI in Arabidopsis thaliana (Fan et al, 2022). The Pep‐13, INF1, and XEG1 proteins of tobacco and potato oomycetes activate plant defence reactions (Brunner et al, 2002; Kamoun et al, 1998).…”

An F‐box protein attenuates fungal xylanase‐triggered immunity by destabilizing LRR‐RLP NbEIX2 in a SOBIR1‐dependent manner

“…For instance, Arabidopsis TMM (TOO MANY MOUTHS; Yang & Sack, 1995), CLV2 (CLAVATA2; Kayes & Clark, 1998) and RLP44 are required for regulating stomata distribution, meristem and organ development, and cell fate in the root vasculature (Holzwart et al ., 2018), respectively. Arabidopsis AtRLP23, AtRLP30, AtRLP32 and AtRLP42, recognizes a conserved amino acid peptide of NLP proteins (Albert et al ., 2015), Sclerotinia sclerotiorum elicitor SCFE1 (Zhang et al ., 2013), proteobacterial translation initiation factor IF1 (Fan et al ., 2022) and fungal endopolygalacturonases (Zhang et al ., 2021), respectively. Nicotiana benthamiana NbRE02 and NbRXEG1 induce pattern‐triggered immunity after recognizing small cysteine‐rich protein VmE02 from apple canker pathogen Valsa mali (Nie et al ., 2021) and Phytophthora sojae PsXEG1 (Y. Wang et al ., 2018), respectively.…”