Biological control organisms (BCOs) can form an important component of more sustainable agriculture. Trichoderma spp. are soil fungi with great potential in this respect. They can trigger induced systemic resistance (ISR) in the plant, leading to a more rapid and robust systemic activation of defense when the plant is subsequently challenged by a pathogen. However, genome-wide investigations of the tripartite plant-Trichoderma-pathogen interaction are scarce, although they provide substantial novel information to improve our understanding of ISR and form the basis for development of rational disease management options. In addition, root responses have been neglected despite the fact that they are the first point of contact for soil microbes and drive above-ground plant responses. The research objective of this project is to identify the defining plant responses originating in roots that drive the ISR process in the Arabidopsis-Fusarium-Trichoderma interaction. This will be achieved by a comparative genomics study of the tripartite interaction in Arabidopsis roots, with Fusarium as soil-borne plant pathogen (core expertise of outgoing host CSIRO Plant Industry Brisbane, Australia) and Trichoderma as BCO (core expertise of return host CPMG, KU Leuven, Belgium). The unique character of this project is to bridge research domains on Trichoderma and Fusarium plant responses, thereby focusing on the largely unknown processes that take place in plant roots. Novel expertise on this interaction will be acquired during the outgoing phase and transferred to the ERA for implementation at the return host institute, in collaboration with the outgoing host and afterwards also other ERA laboratories, to the benefit of biocontrol research in general. In addition, the project foresees a thorough complementary skills training for the applicant. Overall the project is aimed at turning the applicant into a well-trained, internationally-oriented expert in biocontrol and ISR mechanisms.