Bacteria in the genus Streptomyces are effective biological control agents for management of fungal plant pathogens: A meta-analysis

Authors: Leblanc, Nicholas

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2021
Publication Date: 11/12/2021
Citation: LeBlanc, N.R. 2021. Bacteria in the genus Streptomyces are effective biological control agents for management of fungal plant pathogens: A meta-analysis. Biocontrol. 67:111-121. https://doi.org/10.1007/s10526-021-10123-5.
DOI: https://doi.org/10.1007/s10526-021-10123-5

Interpretive Summary: Agricultural and horticultural crops are under continuous threat from diseases caused by fungal plant pathogens. Chemical fungicides are an important tool for managing these diseases but can have negative impacts on the environment and are incompatible with organic agriculture. An alternative disease management strategy that is environmentally friendly and compatible with organic agriculture is to use beneficial microbes that suppress disease. The goal of this research was to test if beneficial microbes called Streptomyces bacteria can reduce disease by statistically analyzing previously published data. Statistical analysis of 160 datasets showed application of beneficial Streptomyces bacteria reduced disease on many different crops by an average of 56%. Further analyses demonstrated disease was reduced the most when Streptomyces bacteria were applied under high disease pressure and when plants were grown under controlled greenhouse conditions. In addition, Streptomyces were most effective at controlling diseases on tomato plants infected by a common fungal plant pathogen called Fusarium oxysporum that lives in the soil. This study shows beneficial Streptomyces bacteria can be used to control fungal plant pathogens and should be considered as a viable alternative to chemical fungicides.

Technical Abstract: Plant diseases caused by fungal plant pathogens are a significant constraint on the global production of horticultural and agronomic crops. Synthetic chemical fungicides are an important tool for managing these diseases but have negative impacts on the environment and are incompatible with organic agriculture. Application of bacteria in the genus Streptomyces Waksman and Henrici 1943 (Approved Lists 1980) as biological control agents is an alternative disease management strategy that has reduced environmental impacts and is compatible with organic agriculture. The goal of this study was to conduct a meta-analysis to test if Streptomyces biological control agents reduce disease caused by fungal plant pathogens and identify factors that alter biological control efficacy of these bacteria. Data were compiled from 160 studies representing 44 publications that tested the effect of Streptomyces on diseases caused by fungal plant pathogens of agronomic and horticultural crops. Overall, Streptomyces biological control agents significantly reduced disease by 56% compared to negative control groups. Additional analyses showed Streptomyces reduced disease caused by soilborne pathogens marginally more than disease from foliar pathogens. Biological control efficacy increased under controlled environments and when Streptomyces bacteria were applied under high disease pressure. Among different fungal pathogens and hosts, Streptomyces were most effective at controlling the soilborne pathogen Fusarium oxysporum Schltdl. and diseases of Solanum lycopersicum L. These results confirm Streptomyces reduce disease caused by fungal plant pathogens and provide novel insight into ways biological control efficacy can be further optimized by considering the production environment and pathogen-host combinations.