Poster #18

Multipartite symbioses of Mimosa scabrella: interactions among partners determine biological processes
S. P. PRIMIERI , P. M. ANTUNES
Instituto Federal de Santa Catarina (IFSC), Câmpus Lages, Lages, SC 88506-400, Brazil

Mimosa scabrella stands out as a rapidly growing leguminous tree species indigenous to the Araucaria Forest of Brazil. This species engages in multipartite symbiotic associations, including arbuscular mycorrhizal fungi (AMF), N2-fixing bacteria (NFB), and nodule-associated bacteria (NAB). Despite the recognized importance of these interactions, their dynamics and consequent impacts on the host remain poorly understood. Here we present results from experiments designed to investigate the contributions of these symbionts in M. scabrella. We found that select species of NFB exhibited varying capacities to meet the host’s nitrogen (N) requirements. To elucidate the mechanisms underlying such variability, we isolated NAB species from nodules. Subsequent inoculation of plants with these isolated strains revealed a 57.7% reduction in nodule abundance. Further investigations into dual inoculation showed that co-inoculation of M. scabrella with AMF alongside NFB resulted in a 71% increase in biomass compared to individual treatments, indicating a synergistic effect between these symbiotic partners. Conversely, when NAB were introduced in conjunction, total AM root colonization experienced a significant reduction of approximately 50% in the tetrapartite compared to the tripartite symbiotic. These findings demonstrate the ecological complexity of multipartite symbioses which may help explain context dependency in biological processes and their associated functional ecology.