Application and mode of action of a Bacillus amyloliquefaciens subsp. plantarum biocontrol organism against foliar fungal and bacterial pathogens of broad acre crops

Novel biocontrol organisms can help farmers reduce the need the chemical pesticides. However, bridging the gap from laboratory research to true field efficacy involves intelligent design of assay and screening cascades that increase reliability and complexity while decreasing the number of false positives that are passed on through screens to expensive field trials.  Building effective assays for agricultural applications must at some point involve live plants, however doing this on a greenhouse scale means small trials and long trial application periods.  The need to have more high throughput assays on live plants has led to Novozymes using plant phenotyping on the ScanalyzerHTS system from LemnaTec GmbH. The biocontrol assay is based on Arabidopsis thaliana, which is a small flowering plant widely used as a model organism in plant biology. Arabidopsis is not of major agronomic significance, but it offers important advantages for basic research in genetics and molecular biology since it can be used in high-throughput screening as several plants can be grown in the space of a microtiter plate, and the short growth cycle means the number of experiments and replicates that can be completed is also high.  Experiments using a commercial biocontrol organism based on Bacillus amyloliquefaciens subsp. plantarum validated the assays ability to discern differences in the level of pathogenicity of the fungus Colletotrichum higginsianum.  Sensitivity of the response of this in planta assay was shown with experiments using deletions/up-regulations of key antifungal metabolites from the biocontrol organism.