Soil bugs could help farmers tackle crop diseases, say scientists

Dr Alba Pacheco-Moreno of the John Innes Centre is researching new ways to protect crops from diseases such as potato scab

Dr Alba Pacheco-Moreno of the John Innes Centre is first author of a new study exploring new ways to protect crops from diseases such as potato scab - Credit: Alba Pacheco-Moreno / JIC

Beneficial bacteria in the soil can be harnessed to help farmers control devastating crop diseases, said Norwich scientists.

A team from the John Innes Centre (JIC) has published a study exploring how crops can be protected from bacterial infection without the cost and environmental damage of chemical treatments.

The researchers isolated and tested hundreds of strains of Pseudomonas bacteria from the soil of a commercial potato field, and then sequenced the genomes of 69 of these strains.

By comparing those shown to suppress pathogen activity with those that did not, the team identified a key mechanism in some strains which protected the potato crop from harmful disease-causing bacteria.

They showed that the production of small molecules called cyclic lipopeptides have an antibacterial effect on the bacteria that cause potato scab - a disease which causes unsightly blemishes and can make potato crops unsellable, causing major losses.

These small molecules also help the protective Pseudomonas bacteria colonise the plant roots.

Dr Alba Pacheco-Moreno of the JIC, who is the first author of the study, said: “By identifying and validating mechanisms of potato pathogen suppression we hope that our study will accelerate the development of biological control agents to reduce the application of chemical treatments which are ecologically damaging.

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"The approach we describe should be applicable to a wide range of plant diseases because it is based on understanding the mechanisms of action that are important for biological control agents."

The study, published in the scientific journal eLife, proposes a method using high-speed genetic sequencing to screen the soil's micro-organisms to find therapeutic bacteria and identify which molecules are being produced to suppress pathogenic bacteria.

Researchers say it can also show how these beneficial bugs are affected by agronomic factors such as irrigation, which can cause substantial changes to the population of Pseudomonas bacteria in the soil.

The next step is to put the beneficial bugs back into the same field in greater numbers or in mixed "cocktails" of bacterial strains as "microbiome boosters", which could be applied as seed coatings, as a spray or via drip irrigation, says the study.

Potatoes infected with potato scab, a bacterial disease that causes major losses for farmers

Potatoes infected with potato scab, a bacterial disease that causes major losses for farmers - Credit: Alba Pacheco-Moreno