The Recognition of YopJ Family Effectors Depends on ZAR1/JIM2 Immune Complex in Nicotiana benthamiana

TL;DR

This study identifies how immune receptors in Nicotiana benthamiana recognize YopJ family effectors from plant pathogens and trigger immune responses.

Contribution

The study reveals the genetic basis for YopJ effector recognition by NbZAR1/JIM2 and NbPtr1 in N. benthamiana.

Findings

Twelve YopJ family effectors are recognized by NbZAR1 or NbZAR1 and NbPtr1 in N. benthamiana.

YopJ effector-induced cell death is differentially suppressed by the deacetylase SOBER1.

The study provides a foundation for understanding the activation mechanisms of NbZAR1/JIM2 and NbPtr1.

Abstract

Pathogens deploy effector proteins to manipulate host physiology and promote infection. YopJ family effectors are highly conserved across bacterial genera that cause crop diseases. Nucleotide‐binding leucine‐rich repeat receptors (NLRs) play a central role in direct or indirect recognition of effectors and trigger immune responses, including hypersensitive cell death (HR). Two NLRs, Nicotiana benthamiana homologues of Pseudomonas tomato race 1 (NbPtr1) and HOPZ‐ACTIVATED RESISTANCE 1 (NbZAR1), were recently identified as independently recognising two YopJ family effectors, HopZ5 and AvrBsT/XopJ2. NbZAR1 also detects XopJ4 via the receptor‐like cytoplasmic kinase XOPJ4 IMMUNITY 2 (JIM2). Here, we conducted Agrobacterium‐mediated transient expression assays with 20 YopJ family effectors from five phytopathogenic bacterial genera and identified 12 YopJ family effectors that are recognised either by NbZAR1 or independently by NbZAR1 and NbPtr1. Furthermore, we show that YopJ family effector‐induced HR is differentially suppressed by the deacetylase SUPPRESSOR OF AVRBST‐ELICITED RESISTANCE 1, suggesting more than one mechanism for YopJ family effector recognition. This work provides the genetic basis of the recognition of YopJ family effectors in N. benthamiana and lays a foundation for the mechanistic study of NbZAR1/JIM2 and NbPtr1 mode of activation.

The cell death triggered by different YopJ family effectors in Nicotiana benthamiana results from NbZAR1 and/or NbPtr1 activation and is differentially suppressed by the deacetylase SOBER1.

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