The colonization of land by plants over 500 million years ago was a significant event in Earth's history, leading to the establishment of land flora that transformed the biosphere and atmosphere. However, to access the mineral nutrients essential for growth and proliferation, early rootless plants needed to form intimate relationships with symbiotic arbuscular mycorrhizal fungi (AMF) that liberated and transferred nutrients from rocks to the plant in exchange for carbon fixed through photosynthesis. Recent discoveries challenge the traditional view that AMF played the primary role in facilitating the colonization of Earth's landmasses by plants. Instead, the Mucoromycotina "fine root endophyte" (MFRE) fungi, which are taxonomically distinct from AMF, may have also played a critical role in this process.
Recent findings demonstrate that symbiosis with MFRE is not limited to early diverging plant lineages, but is present in plants spanning the entire land plant phylogeny. However, the precise host range of MFRE symbionts remains unknown, which limits our understanding of the significance of MFRE in ecosystem structure and function. The most recent findings show that MFRE symbioses are functionally distinct from AMF symbioses in terms of the nutrients supplied to their hosts and their responses to changing atmospheric CO2 concentrations. These discoveries challenge much of what we thought we knew about plant-fungal symbioses, and the fundamental biology of MFRE-plant symbioses remains largely unknown.
MYCOREV aims to address these critical knowledge gaps regarding the diversity, structure, and functional significance of plant-MFRE symbioses. By testing the overarching hypothesis that "MFRE play a major role in plant nutrition and nutrient cycling in modern terrestrial ecosystems," this project will pave the way for a revolution in mycorrhizal research in the 21st century. Understanding the complexity of plant-fungal symbioses and their responses to environmental change is essential for regulating plant communities, ecosystem structure and function, climate, and sustainable agriculture now and in the future. The project is based on three key objectives:
OBJ 1: Determine identity, frequency, diversity, host range and relatedness of MFRE in plants across phylogenetic, developmental and ecological gradients.
OBJ 2: Define diagnostic ultrastructure in MFRE vs. AMF symbiotic interfaces and characterise the spatial distribution of each symbiont in planta in single and dual fungal colonisations in multiple plant species and determine how they are affected by changes in atmospheric CO2 relevant to future predicted changes.
OBJ 3: Quantify functional differences between MFRE- and AMF-plant symbioses in terms of carbon and nutrient fluxes between fungi and host plants in single and dual colonisations across a range of organic and inorganic nutrient sources in terms of type, quantity, metabolism and temporal dynamics of resource exchange and how these are affected by changes in atmospheric CO2.
