# Mitochondrial Protein MjEF‐Tu is Secreted into Host Plants by Nematodes Eliciting Immune Signaling and Resistance

## TL;DR

A nematode's mitochondrial protein triggers plant immune responses by interacting with a plant receptor, revealing a new way pathogens communicate across species.

## Contribution

The first identified plant-parasitic animal-derived proteinaceous PAMP/PRR pair and the first example of a mitochondrial pathogen protein acting as a cross-kingdom signal.

## Key findings

- MjEF-Tu from nematode mitochondria is secreted into host plants and activates immune responses via AtEFR.
- An 18-aa sequence in MjEF-Tu is responsible for its immunogenic activity.
- MjEF-Tu and its Nelf18 fragment enhance plant resistance to multiple pathogens.

## Abstract

Little is known about plant‐parasitic animal‐derived pathogen‐associated molecular pattern (PAMP)/ pattern‐recognition receptor (PRR) pairs. Additionally, mitochondrial proteins have not previously been reported to be secreted into hosts by pathogens. Here, it is found that the Meloidogyne javanica elongation factor thermo unstable (EF‐Tu) (MjEF‐Tu) located in the nematode mitochondria is up‐regulated and secreted into the host plant during nematode parasitism. MjEF‐Tu interacts with the PRR Arabidopsis thaliana EF‐Tu receptor (AtEFR), triggering the plant hallmark defence responses mediated by AtEFR. An 18‐aa sequence (Nelf18) in the N terminus of the nematode EF‐Tu contributes to the immunogenic activity. M. javanica water extract and mitochondrial extract also induce plant immunity sensed by AtEFR, owing to the presence of MjEF‐Tu. In addition, Nelf18 enhances plant resistance to nematode, virus, and bacterial infections depending on AtEFR. These findings first demonstrate that mitochondrial proteins from pathogens can be secreted into hosts and function as a cross‐kingdom signal and identified the first plant‐parasitic animal‐derived proteinaceous PAMP/PRR pair, providing novel insights into host‐pathogen interactions.

This study reports that the mitochondrial protein EF‐Tu from Meloidogyne javanica is secreted into the host plant during nematode parasitism, where it interacts with the PRR AtEFR, thereby activating AtEFR‐mediated plant immune responses. This work represents the first demonstration that mitochondrial proteins from pathogens can act as cross‐kingdom signaling molecules and identifies the first plant‐parasitic animal‐derived proteinaceous PAMP/PRR pair.