Scientists in the UK have developed an innovative method of controlling crop diseases using native, beneficial soil bacteria.
Researchers hope the innovation will help farmers cut the financial costs of treating diseases, as well as reduce the environmental impact of chemical treatments currently used in agriculture.
Using soil from a commercial potato field, scientists at the John Innes Centre isolated and tested hundreds of strains of Pseudomonas — a bacteria that have been widely studied as biological control agents due to their secretion of natural products that promote plant growth and suppress pathogens. From there, they sequenced the genomes of 69 of the strains.
By comparing the genomes of strains shown to suppress pathogen activity with those that didn’t, the team identified a key mechanism that protected the potato plants from disease-causing bacteria.
Then using a combination of chemistry, genetics and plant infection experiments, they showed that the production of small molecules called cyclic lipopeptides is important to the control of potato scab, a bacterial disease that causes major losses to potato harvests.
These small molecules have an antibacterial effect on the pathogenic bacteria that cause potato scab, and they help the protective Pseudomonas move around and colonise the plant roots.
The experiments also showed that irrigation causes substantial changes to the genetically diverse Pseudomonas population in the soil.
Wide application potential
Researcher Dr Alba Pacheco-Moreno said by identifying mechanisms of potato pathogens suppression, the research team hoped their study would accelerate the development of biological control agents to reduce the application of chemical crop treatments.
“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,” she added.
The study, which appeared in the journal eLife, proposes a method by which researchers can screen the microbiome of virtually any crop site, and take into account varying soil, agronomic and environmental conditions.
By exploiting advances in high-speed genetic sequencing, the method can screen the soil microbiome for therapeutic bacteria and work out which molecules are being produced to suppress pathogenic bacteria.
They can also show how these beneficial bugs are affected by agronomic factors such as soil type and irrigation.
Boosting the microbiome
The next step for the approach is to put the beneficial bugs back into the same field in greater numbers, or in cocktails of mixed strains as a soil microbiome boosting treatment.
“The massive advantage of this approach is that we are using bacterial strains that are taken from the environment and put back in the same specific biological context in larger numbers, so there is no ecological damage,” added Dr Jacob Malone, Group Leader at the John Innes centre and co-corresponding author of the study.
Potential methods to apply the microbiome boosters include applying the bacterial cocktails as seed coatings, as a spray or via drip irrigation.
Read the full research report in the journal eLife.
