A predatory myxobacterium controls cucumber Fusarium wilt by regulating the soil microbial community

Xianfeng Ye,Hui Wang,Ruifu Zhang,Yan Qiao,Xue Luo,Hui Cao,Bo Zhang,Rui Li,Zhoukun Li,Jiaqin Fan,Yongkai Li,Zhongli Cui,Yan Huang,Wenhui Wang,Jie Zhou

doi:10.1186/s40168-020-00824-x

Abstract

BackgroundMyxobacteria are micropredators in the soil ecosystem with the capacity to move and feed cooperatively. Some myxobacterial strains have been used to control soil-borne fungal phytopathogens. However, interactions among myxobacteria, plant pathogens, and the soil microbiome are largely unexplored. In this study, we aimed to investigate the behaviors of the myxobacterium Corallococcus sp. strain EGB in the soil and its effect on the soil microbiome after inoculation for controlling cucumber Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (FOC).ResultsA greenhouse and a 2-year field experiment demonstrated that the solid-state fermented strain EGB significantly reduced the cucumber Fusarium wilt by 79.6% (greenhouse), 66.0% (2015, field), and 53.9% (2016, field). Strain EGB adapted to the soil environment well and decreased the abundance of soil-borne FOC efficiently. Spatiotemporal analysis of the soil microbial community showed that strain EGB migrated towards the roots and root exudates of the cucumber plants via chemotaxis. Cooccurrence network analysis of the soil microbiome indicated a decreased modularity and community number but an increased connection number per node after the application of strain EGB. Several predatory bacteria, such as Lysobacter, Microvirga, and Cupriavidus, appearing as hubs or indicators, showed intensive connections with other bacteria.ConclusionThe predatory myxobacterium Corallococcus sp. strain EGB controlled cucumber Fusarium wilt by migrating to the plant root and regulating the soil microbial community. This strain has the potential to be developed as a novel biological control agent of soil-borne Fusarium wilt.6RWdjdPf3LfQd4sE1BE91JVideo abstract.

Highlights

Myxobacteria are micropredators in the soil ecosystem with the capacity to move and feed cooperatively
Our results revealed that myxobacterial predation of FOC and the alteration of the rhizosphere microbial community contributed to the efficient suppression of cucumber Fusarium wilt disease
Solid-state fermented strain EGB exhibited efficient biocontrol of cucumber Fusarium wilt in pot- and fieldscale experiments Previous results showed that liquid culture of strain EGB exhibited excellent biocontrol of cucumber Fusarium wilt in pot experiments [25]

Summary

Introduction

Myxobacteria are micropredators in the soil ecosystem with the capacity to move and feed cooperatively. Numerous biological control agents (BCAs) have been studied, but only a limited number of strains from the genera Bacillus, Pseudomonas, Streptomyces, Trichoderma, Coniothyrium, and Gliocladium and nonpathogenic Fusarium have been commercially developed [4]. Once applied to the soil, BCAs interact with the host plants, native soil microbes, target soil-borne pathogens, and the edaphic environment [5]. Understanding these ecological interactions is critical for the commercial development of BCAs [6]. The fact that a community composed of non-antagonistic bacteria from multiple parallel mineralization systems could suppress Fusarium wilt disease indicates the importance of the microbial community structure to the biocontrol capacity of BCAs [16]

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