Protozoa as drivers for soil disease suppressiveness
Crop losses due to pathogens are important world-wide and expected to increase under climate change. Soil-borne diseases are especially problematic as they cannot be controlled directly in the soil but have to be controlled by preventive measures. Biocontrol by adding antagonistic bacteria or fungi is an environmentally friendly disease control strategy. However, biocontrol research has rarely considered that bacteria are under predation pressure from unicellular protozoa in the soil. Recent studies have shown that bacterial metabolites with anti-fungal activity also are involved in the defense against protozoan predators. Therefore, an increased disease suppressiveness of bacterial communities as a response to protozoan predation can be hypothezised. In this project I investigate a novel strategy in biocontrol: to use protozoa to promote rhizosphere bacteria antagonistic to fungal pathogens and increase disease suppression. First, I will examine the effect of different protozoa on disease suppression and the expression of genes involved in biocontrol in order to identify the best protozoan candidates for use as a biocontrol strategy. Second, I will assess the potential of protozoa as predictors of soil disease suppressiveness by correlating the protozoan communities present in agricultural soils to disease suppression. The project runs for three years (2016-2018) and is a collaboration with researchers at the Swedish University of Agricultural Sciences and Utrecht University in the Netherlands.