Commensal Pseudomonas strains facilitate protective response against pathogens in the host plant

Or Shalev,Detlef Weigel,Derek S Lundberg,Pratchaya Pramoj Na Ayutthaya,Haim Ashkenazy,Talia L Karasov

doi:10.1038/s41559-022-01673-7

Abstract

The community structure in the plant-associated microbiome depends collectively on host–microbe, microbe–microbe and host–microbe–microbe interactions. The ensemble of interactions between the host and microbial consortia may lead to outcomes that are not easily predicted from pairwise interactions. Plant–microbe–microbe interactions are important to plant health but could depend on both host and microbe strain variation. Here we study interactions between groups of naturally co-existing commensal and pathogenic Pseudomonas strains in the Arabidopsis thaliana phyllosphere. We find that commensal Pseudomonas prompt a host response that leads to selective inhibition of a specific pathogenic lineage, resulting in plant protection. The extent of protection depends on plant genotype, supporting that these effects are host-mediated. Strain-specific effects are also demonstrated by one individual Pseudomonas isolate eluding the plant protection provided by commensals. Our work highlights how within-species genetic differences in both hosts and microbes can affect host–microbe–microbe dynamics.

Highlights

The community structure in the plant-associated microbiome depends collectively on host–microbe, microbe–microbe and host–microbe–microbe interactions
Because we wanted to study interactions that are likely to occur in nature, we used A. thaliana genotypes that originated from the same plant populations near Tübingen, Germany[28], from which the Pseudomonas strains had been isolated (Fig. 1a)
We have described two general differences between pathogenic and commensal Pseudomonas: (1) on average, pathogens have a greater impact per a given load on plant growth than commensals do and (2) pathogens can reach higher titre in A. thaliana leaves than commensals can

Summary

Introduction

The community structure in the plant-associated microbiome depends collectively on host–microbe, microbe–microbe and host–microbe–microbe interactions. Like other complex organisms, host a diverse set of microbes The assembly of these microbial communities is shaped both by host–microbe and microbe–microbe interactions. In the case of pathogens, there is often a co-evolutionary arms race, in which plants evolve recognition and immune tools to control the microbes, while microbes evolve evasion and an offensive arsenal to further populate the plant[7,8] These co-evolutionary dynamics typically fuel the generation of genetic diversity within both host and microbe, and the dependence of microbial colonization and host health on intraspecific variation has been widely documented[1,9,10,11]. The role of fine-grained taxonomic differences has often been overlooked in the context of characterizing and analysing plant microbiota, limiting our understanding of how genetic variation among closely related strains affects plant–microbe– microbe interactions

Methods

Results

Conclusion