High dependence on nitrogen-fixing bacteria in a Neotropical legume species

Author(s)

Souza, Caroline ; Leal, Laura C. ; Lima, Vanessa ; Melati, Bruno ; Centeno, Danilo ; Gross, Eduardo ; Urzedo, Alessandro L. ; Nogueira, Anselmo

• Document type: Journal article
• Source: SYMBIOSIS; v. N/A, p. 10-pg., 2025-03-20.

Abstract

Mutualisms are cooperative interactions between species that exhibit varying degrees of partner dependence. In a greenhouse experiment, we investigated the dependence of the native legume species Chamaecrista nictitans (L.) Moench on its nitrogen-fixing bacteria partners, rhizobia. Our study aimed to determine the nature of this association and the level of plant dependence on rhizobia. We conducted a manipulative experiment in a climatically controlled greenhouse using sterilized soil, where we cultivated 180 C. nictitans plants, 90 plants with rhizobia (R+), and the remaining 90 plants without rhizobia (R-) inoculation (exclusion treatment). We assessed plant dependence on nitrogen-fixing bacteria by comparing survival rates, growth patterns, and bud and flower production between R + and R- plants. Additionally, we investigated the investment of R + plants in root nodulation and its influence on plant biomass. The results supported a highly dependent association between C. nictitans and nitrogen-fixing bacteria. R- plants exhibited increased mortality rates, stunted growth, and a complete absence of reproductive structures. R + plants that produced many nodules had a higher accumulated dry biomass. This study underscores the variability in dependence within mutualistic associations in tropical ecosystems. Understanding partner dependence in these habitats is crucial for unraveling the ecological and evolutionary processes underlying the mutualisms, especially in tropical ecosystems. (AU)

• FAPESP's process: 17/13358-1 - Competition-based screening of partners as a stabilizing mechanism in ant-plant facultative mutualisms
• Grantee: Laura Carolina Leal de Sousa
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/19544-7 - Synergistic effect of multiple mutualists on plants: how bacteria, ants and bees contribute to the evolution of a hyper-diverse lineage of legumes
• Grantee: Anselmo Nogueira
• Support Opportunities: BIOTA-FAPESP Program - Young Investigators Grants