Abstract
The use of beneficial microorganisms for the biological control of plant diseases and pests has emerged as a viable alternative to chemical pesticides in agriculture. Traditionally, microbe-based biocontrol strategies for crop protection relied on the application of single microorganisms. However, the design of microbial consortia for improving the reliability of current biological control practices is now a major trend in biotechnology, and it is already being exploited commercially in the context of sustainable agriculture. In the present study, exploiting the microbial library of the biocontrol company Koppert Biological Systems, we designed microbial consortia composed of carefully selected, well-characterized beneficial bacteria and fungi displaying diverse biocontrol modes of action. We compared their ability to control shoot and root pathogens when applied separately or in combination as microbial consortia, and across different application strategies that imply direct microbial antagonism or induced systemic plant resistance. We hypothesized that consortia will be more versatile than the single strains, displaying an extended functionality, as they will be able to control a wider range of plant diseases through diverse mechanisms and application methods. Our results confirmed our hypothesis, revealing that while different individual microorganisms were the most effective in controlling the root pathogen Fusarium oxysporum or the foliar pathogen Botrytis cinerea in tomato, the consortia showed an extended functionality, effectively controlling both pathogens under any of the application schemes, always reaching the same protection levels as the best performing single strains. Our findings illustrate the potential of microbial consortia, composed of carefully selected and compatible beneficial microorganisms, including bacteria and fungi, for the development of stable and versatile biological control products for plant protection against a wider range of diseases.
Highlights
A plethora of soil-borne microorganisms live associated with plant roots, and some are detrimental, others provide important benefits to the host plant, from improved nutrition through growth and protection against multiple abiotic and biotic stresses (Bakker et al, 2018)
Using different inoculation methods and two agronomically relevant pathosystems, we demonstrate the advantages of targeting microbial consortia as versatile products for efficient biocontrol of diverse plant diseases
By combining well-characterized and compatible microorganisms, including bacteria and fungi, we demonstrated the potential of microbial consortia to effectively control fungal pathogens with different lifestyles through direct and plant-mediated disease suppression and using different application methods
Summary
A plethora of soil-borne microorganisms live associated with plant roots, and some are detrimental, others provide important benefits to the host plant, from improved nutrition through growth and protection against multiple abiotic and biotic stresses (Bakker et al, 2018). SynComs for Effective Biocontrol sustainability in agriculture (Barea, 2015; Trivedi et al, 2017; Compant et al, 2019). The ability of microorganisms to control pests and diseases has been well documented, but the variability of results often recorded under field conditions is one of the major challenges for wider adoption in agriculture (Trivedi et al, 2017; Mitter et al, 2019). Inconsistent or ineffective performance of single strain inoculants can be related to limited competitiveness against indigenous microbes and the varying environmental conditions (Trivedi et al, 2020). Successful examples of better performance for microbial consortia are comparatively limited and usually relate to growth or yield promotion (Bradácová et al, 2019)
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