Native, beneficial soil bacteria could be the key to controlling potato scab according to a research-industry collaboration led by the John Innes Centre in Norwich. It is hoped that new controls can be developed which are less financially and environmentally costly to the existing chemical options.
The John Innes Centre team 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 the genomes of those strains shown to suppress pathogen activity with those that did not, the team were able to identify a key mechanism in some of the strains that protected the potato crop from harmful 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.
With high-speed genetic sequencing the soil microbiome can be screened for the presence of therapeutic bacteria, and the molecules which 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.
The next step for the new 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.
Dr Jacob Malone, Group Leader at the John Innes Centre commented, “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.”