Experimental evolution of new legume symbionts
Los rizobios son bacterias del suelo capaces de establecer simbiosis mutualistas en los nódulos en las raíces de las plantas leguminosas, proceso durante el cual fijan nitrógeno atmosférico en beneficio de sus hospedadores.
- Salón de Actos del Instituto de Investigaciones Biológicas Clemente Estable / Zoom
Disertante: Philippe Remigi
Laboratoire des Interactions Plantes Microbes-Environnement
INRAE (Instituto Nacional de Investigación para la Agricultura, la Alimentación y el Medio Ambiente) y CNRS (Centro Nacional de Investigación Científica), Francia.
Rhizobia are soil bacteria that can establish mutualistic symbioses within root nodules of leguminous plants, during which bacteria fix atmospheric nitrogen to the benefit of their hosts. Rhizobia form a genetically diverse bacterial group, and phylogenetic analyses have shown that soil bacteria can acquire the ability to establish this symbiosis through horizontal transfer of genes that are essential for nodulation and nitrogen fixation. However, these genes are not always sufficient to transform recipient bacteria into effective legume symbionts. What additional genes and metabolic functions enable bacteria to establish this complex interaction? What evolutionary processes and selective forces drive the transition from soil bacterium to rhizobium?
To address these questions, our team has conducted a bacterial evolution experiment aimed at reproducing the emergence of new rhizobia in the laboratory. We introduced the symbiotic plasmid from the rhizobium Cupriavidus taiwanensis into the phytopathogenic bacterium Ralstonia solanacearum, and subjected the resulting chimeric strain to successive cycles of nodulation on the legume Mimosa pudica. During this experiment, evolved bacteria gradually acquired different symbiotic properties, without reaching a bona fide mutualistic, nitrogen-fixing lifestyle. In this talk, I will present our efforts to understand the dynamics of bacterial adaptation in this experiment, and to identify the genetic bases of phenotypic shifts. I will then discuss possible barriers to the acquisition of nitrogen fixation, and strategies to overcome them.
Enlace para la reunión de Zoom: https://us06web.zoom.us/j/88211784186?pwd=fVPjI2MENqaddTfvIMVe2Ni0emWjIm.1
ID de reunión: 882 1178 4186
Código de acceso: 089322