# Rapid local and systemic jasmonate signalling drives the initiation and establishment of plant systemic immunity

## TL;DR

The paper shows how plants rapidly activate immunity against pathogens using jasmonate signaling, tracked with a new reporter system.

## Contribution

A novel luciferase reporter reveals jasmonate's role in systemic immunity initiation and surface electrical potentials after pathogen recognition.

## Key findings

- JISS1::LUC captures early ETI-elicited systemic immunity signaling independent of classical SAR mutants.
- Jasmonate biosynthesis and perception are essential for SAR against Pseudomonas syringae.
- ETI triggers jasmonate-dependent systemic surface electrical potentials involving glutamate receptors and JISS1.

## Abstract

Successful recognition of pathogen effectors by plant disease resistance proteins, or effector-triggered immunity (ETI), contains the invading pathogen through localized hypersensitive cell death. ETI also activates long-range signalling to establish broad-spectrum systemic acquired resistance (SAR). Here we describe a sensitive luciferase (LUC) reporter that captures the spatial–temporal dynamics of SAR signal generation, propagation and establishment in systemic responding leaves following ETI. JASMONATE-INDUCED SYSTEMIC SIGNAL 1 (JISS1) encodes an endoplasmic-reticulum-localized protein of unknown function. JISS1::LUC captured very early ETI-elicited SAR signalling, which surprisingly was not affected by classical SAR mutants but was dependent on calcium and was also wound responsive. Both jasmonate biosynthesis and perception mutants abolished JISS1::LUC signalling and SAR to Pseudomonas syringae. Furthermore, we discovered that ETI initiated jasmonate-dependent systemic surface electrical potentials. These surface potentials were dependent on both glutamate receptors and JISS1, despite neither JISS1 loss-of-function nor glutamate receptor mutants altering SAR to Pseudomonas syringae. We thus demonstrate that jasmonate signalling, usually associated with antagonism of defence against biotrophs, is crucial to the rapid initiation and establishment of SAR systemic defence responses (including the activation of systemic surface potentials) and that JISS1::LUC serves as a reporter to further dissect these pathways.

A novel reporter captured spatial temporal dynamics of effector-triggered-immunity (ETI)-induced systemic immunity, revealing that signal propagation and establishment in systemic acquired resistance depend on jasmonates. Furthermore, ETI initiates jasmonate-dependent systemic induced surface electrical potentials.