Marina Omacini
University of Buenos Aires
As an Associate Professor at the Faculty of Agronomy, University of Buenos Aires (FAUBA), my research investigates mutualistic interactions, particularly symbiotic relationships with microorganisms in native and invasive plants of Pampean grasslands and crops. I focus on the synergistic effects of coexisting symbioses and how these interactions influence community dynamics and ecological restoration. My work examines the ecological and agronomic significance of various types of plant symbionts—such as non-toxic fungal endophytes for cattle, rhizobia, and mycorrhizal fungi—within the same host plant or neighboring plants, particularly in response to agricultural intensification practices. Additionally, I teach Ecology to graduate students and lead a postgraduate course on Symbiosis Ecology, aiming to deepen ecological understanding and promote sustainable development goals within diverse agroecosystems-
Abstract:
Interplay of symbiotic beings in the Pampa: the encounter between an alien grass and leaf-cutting ants
M OMACIN I, JE FIORENZA, A MINAS, S MENDEZ, P. FERNANDEZ
Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Agronomía, Buenos Aires, Argentina (CONICET-FAUBA, IFEVA)
Exploring biological invasions requires understanding symbiotic relationships across trophic levels. This study connected experimental results to illustrate how three types of symbiotic fungi indirectly interact throughout an invasive plant's life cycle, potentially conferring herbivore protection. We focused on the annual grass Lolium multiflorum (Italian ryegrass), co-introduced with the asexual endophyte Epichloë occultan s (Ascomycota: Clavicipitacea), and naturalized in the Pampa region. Field observations in experimental patches dominated by ryegrass plants with or without the endophyte (E+ and E-) revealed that this symbiosis could increase the emission of Z3 hexenyl acetate (Z3-HAC), a green leaf volatile. Z3-HAC production comprised over 95% of the emitted compounds when defensive loline alkaloids were at their lowest in E+ leaves. Notably, there were no significant differences in volatile emission between E+ and E- plants uncolonized by soil mycorrhizal fungi. Furthermore, leaf-cutting ants Acromyrmex ambiguus displayed a delay avoidance for E+ young plants, and Z3-HAC exposure modified the growth of Leucoagaricus sp ( Agaricaceae, Basidiomycota ), the ant´s obligate symbiotic fungus that modulates their foraging behavior. These findings reveal intricate interactions among endophytic, arbuscular mycorrhizal, and leaf-cutting ants´ fungi, highlighting microbial coalitions and collisions in plant defense mechanisms.
Research interests: Symbosis ecology, agroecosystems, grasslands, grass-endophyte symbiosis, mycorrhiza
My Sessions
Interplay of symbiotic beings in the Pampa: the encounter between an alien grass and leaf-cutting ants
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