Our Projects
Transcriptional regulation of arbuscule accommodation inside plant cells
Arbuscules are highly branched hyphal structures of arbuscular mycorrhiza fungi, which form inside root cortex cells. Arbuscules and the root cortex cells they colonize represent the major site for symbiotic nutrient exchange. Arbuscule formation, requires signal exchange and subcellular remodeling of the host cell and is accompanied by cell-autonomous transcriptional changes. We investigate transcription factor complexes and networks regulating transcriptional changes required for arbuscule development
Regulatory networks of plant cell rearrangement during symbiont accommodation (RECEIVE)
Arbuscular mycorrhiza (AM) is an ancient plant-fungus symbiosis that is wide-spread in the plant kingdom. AM improves plant nutrition, stress resistance and general plant performance and thus represents a promising addition to sustainable agricultural practices. Mineral nutrients are released from the fungus to the plant at highly branched hyphal structures, the arbuscules, which form inside root cortex cells. Like the cells of other multicellular eukaryotes, plant cells show a remarkable developmental plasticity. Single cell re-differentiation is a fascinating process during arbuscule development, which can be conceptually separated into distinct stages controlled by the plant cell which precisely guide the step-wise formation of different parts of the arbuscule. It involves cell autonomous transcriptional reprogramming and subcellular remodelling, leading to repositioning of subcellular structures and cell polarization and multiplication of organelles. RECEIVE utilizes an integrated strategy combining transcriptional profiling, transcription factor identification, interaction network analysis with reverse genetics and cell biological techniques to understand the coordinated step-wise progression of arbuscule development. RECEIVE builds on the hypothesis that each stage of arbuscule development is accompanied by a stage-specific wave of gene expression and that transcriptional regulation is a key determinant of the developmental progress from stage to stage. The characterisation of these waves and the identification of the underlying transcriptional regulatory nodes is the focus of this project. RECEIVE aims to bridge a major knowledge gap about the molecular basis of one of the most important symbioses on earth.
This project was funded until July 2024 by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 759731, ERC-2017-StG).
Nutrient and metabolite exchange at the plant-fungal interface
Arbuscular mycorrhiza fungi provide mineral nutrients to the plant and receive photosynthetically-fixed carbon in return. This exchange of nutrients and metabolites mainly occurs between arbuscules and arbuscule containing cells. In addition, it is conceivable that the organisms exchange signalling molecules inside root cells. We investigate which nutrients and metabolites are exchanged, what is the mechanism of exchange and how the exchange is regulated. For example, in the past we found that plants provide lipids to AM fungi (Keymer et al., 2017) and not only hexoses as previously assumed.
Molecular exchange at the plant-fungal interface in arbuscular mycorrhiza symbiosis (SymbioticExchange)
Nutrient acquisition is the basis of life. Arbuscular mycorrhiza (AM) symbiosis of plants with nutrient-delivering fungi is detected in the oldest land plant fossils and considered a prerequisite for plant life on land. It is wide-spread in the plant kingdom and its secondary loss is the exception. AM improves plant nutrition, stress resistance and general plant performance. Breeding AM-optimized crops has significant potential for improving food security and sustainable agriculture. Understanding the molecular underpinnings of AM function is thus imperative. The hallmark of the symbiosis are the arbuscules, highly branched hyphal structures, which develop in root cortex cells. They build a large membrane interface with the plant derived peri-arbuscular membrane (PAM) that surrounds them. Most mineral nutrients are delivered from the arbuscules and taken up via the PAM into plant cells through transporter proteins. In return, the fungi receive up to 20% of the photosynthetically-fixed carbon. The balance in mineral-nutrient-gain-for-carbon-loss influences the effect of the symbiosis in plant growth and yield. However, the full range of transported nutrients, any mechanisms regulating transport and the balance in molecular exchange are unknown. ‘SymbioticExchange’ strategically integrates transcriptomics, phosphoproteomics, metabolomics and protein-protein interaction analysis, with reverse genetics, cell biology and transport physiology to identify novel plant and fungal transporters involved in symbiotic nutrient and metabolite exchange, and to understand the molecular mechanisms of their regulation. ‘SymbioticExchange’ will thus deliver major advances on the range of transporters at the plant-fungal interface, the exchanged goods and the regulation of exchange. This important knowledge-base will provide crucial clues on how nutrient exchange can be tuned for profitable agricultural application of one of the most important symbioses on earth.
This project is funded by the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation programme (Grant agreement No. 101089250, ERC-2022-CoG).