Indirect reduction of Ralstonia solanacearum via pathogen helper inhibition

Mei Li,Zhong Wei,Alexandre Jousset,Joost Keuskamp,Jianing Wang,George A Kowalchuk,Yue Yin,Honggui Wang,Qirong Shen,Thomas Pommier,Yangchun Xu,Shaohua Gu

doi:10.1038/s41396-021-01126-2

Abstract

The rhizosphere microbiome forms a first line of defense against soilborne pathogens. To date, most microbiome enhancement strategies have relied on bioaugmentation with antagonistic microorganisms that directly inhibit pathogens. Previous studies have shown that some root-associated bacteria are able to facilitate pathogen growth. We therefore hypothesized that inhibiting such pathogen helpers may help reduce pathogen densities. We examined tripartite interactions between a model pathogen, Ralstonia solanacearum, two model helper strains and a collection of 46 bacterial isolates recovered from the tomato rhizosphere. This system allowed us to examine the importance of direct (effects of rhizobacteria on pathogen growth) and indirect (effects of rhizobacteria on helper growth) pathways affecting pathogen growth. We found that the interaction between rhizosphere isolates and the helper strains was the major determinant of pathogen suppression both in vitro and in vivo. We therefore propose that controlling microbiome composition to prevent the growth of pathogen helpers may become part of sustainable strategies for pathogen control.

Highlights

Plant pathogens have a large negative impact on agricultural production, and there is an urgent need for sustainable strategies to prevent diseases while reducing the environmental footprint of modern agriculture [1]
MATERIALS AND METHODS Rhizosphere soil sampling A total of 20 rhizosphere soil samples (20 tomato plants) were collected at the flowering stage from a tomato field located in Qilin town, Jiangsu province, China, 118°57’ E, 32°03’ N, which had been infested by the pathogen Ralstonia solanacearum for more than 15 years [8]
P 0.1146 0.0032 0.8485 df RESULTS Taxonomic characterization of inhibiting and helping strains of Ralstonia solanacearum from the tomato rhizosphere The 160 non-redundant isolates we examined were classified within four main phyla, with the following distribution: Proteobacteria 33.1%, Firmicutes 25.0%, Bacteroidetes 19.4% and Actinobacteria 22.5%

Summary

Introduction

Plant pathogens have a large negative impact on agricultural production, and there is an urgent need for sustainable strategies to prevent diseases while reducing the environmental footprint of modern agriculture [1].

Results

Conclusion