Are soils suppressive to fungal diseases the sources of biocontrol agents?

Abstract: Soils harbour a wide range of phytoparasitic microorganisms that affect plant growth and health. The purpose of this study was to conduct an intermediate approach between the metagenomic analysis of soil suppressiveness to diseases and the search for fungi whose activities contribute to the inhibition of infectious pathogens. There are two different suppressive soils investigated in this study. The first one is a natural, long-standing Fusarium-wilt suppressive soil from the south of France. This kind of suppressiveness is described as depending on natural microbiological properties of the soil and not of the culture conditions. The second soil is suppressive to Rhizoctonia solani damping-off and was identified in field surveys in the Netherlands conducted by the Institute of Sugar Beet Research in 2004. Unlike natural suppressiveness, this one is induced by crop monoculture. Structural shifts were revealed among rhizosphere fungal communities in suppressive soils in absence and in presence of the pathogen, as well as in conducive soils in two different patho-systems.