The mycoparasitic fungus Clonostachys rosea responds with both common and specific gene expression during interspecific interactions with fungal prey

Clonostachys rosea is a necrotrophic mycoparasitic fungus, used for biological control of plant pathogenic fungi. A better understanding of the underlying mechanisms resulting in successful biocontrol is important for knowledge-based improvements of the application and use of biocontrol in agricultural production systems. Transcriptomic analyses revealed that C.rosea responded with both common and specific gene expression during interactions with the fungal prey species Botrytis cinerea and Fusarium graminearum. Genes predicted to encode proteins involved in membrane transport, biosynthesis of secondary metabolites and carbohydrate-active enzymes were induced during the mycoparasitic attack. Predicted major facilitator superfamily (MFS) transporters constituted 54% of the induced genes, and detailed phylogenetic and evolutionary analyses showed that a majority of these genes belonged to MFS gene families evolving under selection for increased paralog numbers, with predicted functions in drug resistance and transport of carbohydrates and small organic compounds. Sequence analysis of MFS transporters from family 2.A.1.3.65 identified rapidly evolving loop regions forming the entry to the transport tunnel, indicating changes in substrate specificity as a target for selection. Deletion of the MFS transporter gene mfs464 resulted in mutants with increased growth inhibitory activity against F.graminearum, providing evidence for a function in interspecific fungal interactions. In summary, we show that the mycoparasite C.rosea can distinguish between fungal prey species and modulate its transcriptomic responses accordingly. Gene expression data emphasize the importance of secondary metabolites in mycoparasitic interactions.