Characterization of the molecular mechanisms underpinning local and systemic responses in root-microbe multispecies interactions

This project aimed to understand how host-microbiota interactions in natural soil shape and are shaped by local and systemic responses to beneficial and pathogenic root associated fungi. In order to address this, we established a reductionist approach which takes advantage of a gnotobiotic natural soil-based split root system to identify plant and microbe-derived transcripts that locally and systemically affect these interactions. Focus was on the role of local and root to root systemic signalling events on barley root associated fungal microbes. We studied single and joint root infection of barley with the cereal root rot fungal pathogen Bipolaris sorokiniana and with the beneficial root endophyte Serendipita vermifera. The consequences for local and systemic plant immunity were studied by analysis of reciprocal transcriptional responses to fungal colonization. Fungal cell wall degrading enzymes like chitinases and β-1,3-exoglucanases of S. vermifera were highly induced indicating that antagonism might play a role in protecting plant roots. However, transcriptomic analysis of tripartite interaction in the split-root system suggested plausible role of symbiont-modified plant responses in reducing colonization by the pathogen.