Review. Unraveling plant-microbe interaction dynamics: Insights from the Tripartite Symbiosis Model

Plants naturally interact with a diverse array of microorganisms, which influence their fitness in various ways. However, understanding these plant-microbe interactions and applying the knowledge in real-world agricultural systems has been challenging. Most experimental research focuses on bipartite systems, where a single plant species is paired with one microbial species. This oversimplification fails to capture the complexity of natural ecosystems, where plants typically engage with multiple microorganisms simultaneously. One promising model for exploring these complex interactions is the tripartite symbiosis between legumes, arbuscular mycorrhizal fungi (AMF), and nitrogen-fixing rhizobia. This tripartite system provides valuable insights into the intricate relationships that govern plant-microbe dynamics and brings researchers closer to understanding how these multifactorial interactions shape plant health and productivity. In their review, Gorgia and Tsikou examine current knowledge and challenges associated with this system. They highlight that the effects of dual inoculation with both AMF and rhizobia cannot be predicted by simply adding the individual contributions of each microorganism, as indicated by multi-omics analyses. Moreover, factors such as partner compatibility, nutrient availability, environmental conditions, plant autoregulation, and the interactions between microbes inside (intraradical) and outside (extraradical) the root tissue all play critical roles. Together, these factors shape the rhizosphere community, influence root morphology, and ultimately affect the competitive dynamics of plants. Although the tripartite system remains relatively simple, it serves as a foundational model for studying more complex multispecies interactions that could have important applications in agriculture, particularly in enhancing crop productivity and sustainability. (Summary by Ching Chan @ntnuchanlab) Plant, Cell & Environment 10.1111/pce.15341