Importance of N-Acyl-Homoserine Lactone-Based Quorum Sensing and Quorum Quenching in Pathogen Control and Plant Growth Promotion.

Anton Hartmann,Michael Rothballer,Sophia Klink

doi:10.3390/pathogens10121561

Anton Hartmann, Michael Rothballer + Show 1 more

Open Access

https://doi.org/10.3390/pathogens10121561

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Abstract

The biological control of plant pathogens is linked to the composition and activity of the plant microbiome. Plant-associated microbiomes co-evolved with land plants, leading to plant holobionts with plant-beneficial microbes but also with plant pathogens. A diverse range of plant-beneficial microbes assists plants to reach their optimal development and growth under both abiotic and biotic stress conditions. Communication within the plant holobiont plays an important role, and besides plant hormonal interactions, quorum-sensing signalling of plant-associated microbes plays a central role. Quorum-sensing (QS) autoinducers, such as N-acyl-homoserine lactones (AHL) of Gram-negative bacteria, cause a pronounced interkingdom signalling effect on plants, provoking priming processes of pathogen defence and insect pest control. However, plant pathogenic bacteria also use QS signalling to optimise their virulence; these QS activities can be controlled by quorum quenching (QQ) and quorum-sensing inhibition (QSI) approaches by accompanying microbes and also by plants. Plant growth-promoting bacteria (PGPB) have also been shown to demonstrate QQ activity. In addition, some PGPB only harbour genes for AHL receptors, so-called luxR-solo genes, which can contribute to plant growth promotion and biological control. The presence of autoinducer solo receptors may reflect ongoing microevolution processes in microbe–plant interactions. Different aspects of QS systems in bacteria–plant interactions of plant-beneficial and pathogenic bacteria will be discussed, and practical applications of bacteria with AHL-producing or -quenching activity; QS signal molecules stimulating pathogen control and plant growth promotion will also be presented.

Highlights

During the evolution of land plants, plant-associated microbiomes co-evolved and were integrated into microbe–plant holobionts
Recent findings related to acyl-homoserine lactones (AHL)-based quorum-quenching activities and the presence of multiple luxR-solo genes [29] in plant growth-promoting bacteria have opened new insights into modified QS system activities with plant growth-promoting and biocontrol potential
Compounds and the AHL-signalling plant-beneficial bacteria should be acknowledged as important elements in bacteria–plant interactions, leading to plant growth promotion and biological control of plant pathogens

Summary

Introduction

During the evolution of land plants, plant-associated microbiomes co-evolved and were integrated into microbe–plant holobionts. Besides microbially produced plant hormones and a diversity of other metabolites, bacterial quorum-sensing (QS) signalling substances, e.g., of the N-acyl-homoserine lactone (AHL, AI-1) type, play a significant role in beneficial bacteria–plant interaction and pathogen defence [1]. During the course of bacteria–plant interactions, microbial signalling molecules stimulate the priming of specific plant gene expression, leading to enhanced pathogen defence and growth promotion [1].

Results

Conclusion