Periodic Reporting for period 1 - NUCLEAR MIX (Nuclear cooperation and conflict across symbiotic fungal networks)
Reporting period: 2023-01-01 to 2025-06-30
Arbuscular mycorrhizal fungi (AMF) form one of the most widespread symbiotic relationships on Earth. These soil fungi partner with the roots of most land plants, exchanging nutrients they gather from the soil for carbohydrates and fats from their plant hosts. Because AMF can connect with multiple plant species at once, and a single plant can host multiple fungi, they create extensive underground networks called common mycorrhizal networks (CMNs). These networks help maintain soil health, support plant growth, shape plant communities, and store carbon in their mycelia. Becasue of that they are commonly used as organic biofertilizers across the globe.
Despite their ecological and commercial importance, the genetic mechanisms governing the reproduction of these fungi (believed to be asexual organisms) and the connectivity of their underground networks remain unknown. Their networks facilitate large-scale nutrient transfer, but their efficiency varies depending on genetic makeup and structure, but due to their peculiar cell organization and genetic makeup these processes are not clearly understood. AMF possess multinucleate hyphae, meaning that thousands of nuclei coexist within a single continuous cell. Previously, these nuclei were thought to be genetically diverse, challenging the concept of AMF as true individuals. However, recent findings reveal a strict genetic organization: AMF can contain either genetically identical nuclei, or in some rare occasions they contain two nuclear population of unique genetic makeup (two genomes in a cell).
Despite these important recent advances, fundamental questions remain:
• How is genetic diversity generated in AMF?
• Can this variation exist without sexual reproduction?
• How does nuclear diversity impact network stability, nutrient exchange, and in a larger scale ecosystem processes?
How nuclei mix in AMF has significant ecological and agricultural implications. If nuclear competition leads to the exclusion of certain nucleotypes, network connectivity may be disrupted, affecting nutrient flow, plant community composition, and carbon sequestration. Conversely, nuclear cooperation could enhance network stability and resilience. By providing detailed insights into AMF nuclear interaction, we challenge long-standing assumptions about AMF asexuality and the presumed benefits of network connectivity for fungi and plants, reshaping understanding of their reproductive biology and network dynamics. This work opens new possibilities for optimizing mycorrhizal applications in agriculture, potentially improving crop resilience and nutrient uptake. Additionally, by reevaluating the functionality of common mycorrhizal networks, this work can help clarify how AMF shape plant communities and ecosystem dynamics, informing strategies to enhance soil fertility and carbon sequestration for more sustainable land management.
Despite their ecological and commercial importance, the genetic mechanisms governing the reproduction of these fungi (believed to be asexual organisms) and the connectivity of their underground networks remain unknown. Their networks facilitate large-scale nutrient transfer, but their efficiency varies depending on genetic makeup and structure, but due to their peculiar cell organization and genetic makeup these processes are not clearly understood. AMF possess multinucleate hyphae, meaning that thousands of nuclei coexist within a single continuous cell. Previously, these nuclei were thought to be genetically diverse, challenging the concept of AMF as true individuals. However, recent findings reveal a strict genetic organization: AMF can contain either genetically identical nuclei, or in some rare occasions they contain two nuclear population of unique genetic makeup (two genomes in a cell).
Despite these important recent advances, fundamental questions remain:
• How is genetic diversity generated in AMF?
• Can this variation exist without sexual reproduction?
• How does nuclear diversity impact network stability, nutrient exchange, and in a larger scale ecosystem processes?
How nuclei mix in AMF has significant ecological and agricultural implications. If nuclear competition leads to the exclusion of certain nucleotypes, network connectivity may be disrupted, affecting nutrient flow, plant community composition, and carbon sequestration. Conversely, nuclear cooperation could enhance network stability and resilience. By providing detailed insights into AMF nuclear interaction, we challenge long-standing assumptions about AMF asexuality and the presumed benefits of network connectivity for fungi and plants, reshaping understanding of their reproductive biology and network dynamics. This work opens new possibilities for optimizing mycorrhizal applications in agriculture, potentially improving crop resilience and nutrient uptake. Additionally, by reevaluating the functionality of common mycorrhizal networks, this work can help clarify how AMF shape plant communities and ecosystem dynamics, informing strategies to enhance soil fertility and carbon sequestration for more sustainable land management.
To answer these important questions we develop novel approaches using a combination of high-resolution imaging, molecular techniques, and ecological experiments which enable us to investigate nuclear interactions across different scales:
• Super-resolution microscopy and innovative DNA/RNA fluorescence in situ hybridization (FISH) protocols to determine whether coexisting nucleotypes undergo sexual reproduction.
• Fully automated time-lapse microscopy imaging and molecular tools to analyse nuclear interactions in coexisting fungal networks and their effect on fungal fitness.
• In-planta experiments and field sampling to assess how nuclear diversity influences plant communities and ecosystem processes.
Our work so far has led to numerous technological invocations such as our novel culturing system for AMF in microchips and our microfluidic based FISH protocols that allow for high-throughput and cost efficient sample processing and analysis. Another major breakthrough is our custom-built imaging robot, which captures network spatiotemporal growth as well as network interactions in unpresented detail. Furthermore, using high-resolution imaging, we are now able to track cytoplasmic flows inside hyphae, uncovering bi-directional streaming that enhances transport, much like human highways. Finally, our automated nuclear detection in fixed samples provides the first precise view of nuclear distribution in entire undisturbed fungal networks.
• Super-resolution microscopy and innovative DNA/RNA fluorescence in situ hybridization (FISH) protocols to determine whether coexisting nucleotypes undergo sexual reproduction.
• Fully automated time-lapse microscopy imaging and molecular tools to analyse nuclear interactions in coexisting fungal networks and their effect on fungal fitness.
• In-planta experiments and field sampling to assess how nuclear diversity influences plant communities and ecosystem processes.
Our work so far has led to numerous technological invocations such as our novel culturing system for AMF in microchips and our microfluidic based FISH protocols that allow for high-throughput and cost efficient sample processing and analysis. Another major breakthrough is our custom-built imaging robot, which captures network spatiotemporal growth as well as network interactions in unpresented detail. Furthermore, using high-resolution imaging, we are now able to track cytoplasmic flows inside hyphae, uncovering bi-directional streaming that enhances transport, much like human highways. Finally, our automated nuclear detection in fixed samples provides the first precise view of nuclear distribution in entire undisturbed fungal networks.
So far, our work reveals key design principles of symbiotic supply chains by studying mycorrhizal networks, which balance transport efficiency with adaptability. Our research also identifies fungal growth patterns resampling traveling waves which regulate expansion whilst stabilize symbiotic trade. Finally, initial results also demonstrate that when network fuse, nuclear competition can take place leading to dramatic shifts in the species establishment and survival.