Soil microbiome, crop health and productivity

We call the portion of soil closest to the roots of plants the rhizosphere. Some soils are more capable of supporting the suppression of plant disease-causing agents than others, helping to prevent the establishment of pathogens in the rhizosphere of plants. However, the characteristics that define these soils are largely unknown.

The rhizosphere environment is complex, composed primarily of carbon, and also containing several nutrients, which are essential for harboring a diverse microbial community responsible for promoting plant growth and health. The rhizosphere microbiome serves as the first line of defense against plant pathogens, a sustainability factor for agricultural production systems.

Sustainable strategies

Because of this, advancing our understanding of how variations in the composition of rhizosphere microbiomes influence plant diseases is of paramount importance to support innovative strategies that improve plant health and productivity.

A classic agronomic technique is crop rotation, which helps to mitigate the negative impacts of pathogens on agricultural production, breaking the link between the host plant and the pathogens.

But there are new developments, such as synthetic microbial communities – called SynComs – and metabolites produced by roots. These are promising strategies for combating pathogens present in the soil, which are responsible for causing plant diseases. SynComs are being developed as bioproducts to control diseases caused by pathogens present in the soil. However, there is still a long way to go to understand the impacts of SynComs on the rhizosphere of crops and their effectiveness for plant health.

Recent studies have shown that the rhizosphere microbiome is significantly influenced by the metabolism of plant roots. As a result, improving the health status of a plant depends on which microbial populations are able to take advantage of the metabolites produced by the roots.

crop rotation

Studies conducted by Yanyan Zhou’s team, in the laboratory and later in greenhouses and in the field, investigated the effect of management – ​​comparing monoculture and rotation – on the ability of rhizosphere microbiomes to suppress peanut root rot. Compared to crop rotations, monoculture resulted in microbial assemblages that were less effective in suppressing root rot diseases.

Furthermore, the depletion of key rhizosphere organisms in monoculture reduced the ability of plants to protect against pathogens. To overcome this problem, researchers promoted the supplementation of depleted strains, which restored the rhizosphere's resistance to the pathogen.

The merit of Zhou's research lies not in its originality, but in consolidating knowledge of the role of native soil microbes in combating disease and supporting plant health, and indicating the importance of crop rotation, and the potential of using microbial inocula, to regenerate the soil's natural ability to combat plant disease.

*By Décio Luiz Gazzoni, researcher at Embrapa Soja