A phylogenetically conserved group of NF-Y transcription factors interact to control nodulation in legumes

The endosymbiotic association between legumes and rhizobia leads to the formation of root nodules in which differentiated bacteria convert atmospheric nitrogen into a form that can be assimilated by the host plant. Successful root infection by rhizobia and nodule organogenesis require the activation of symbiotic genes that are controlled by a set of early transcription factors (TFs). MtNF-YA1 and MtNF-YA2 are two TFs playing partially redundant functions during several steps of the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti. NF-Y proteins are part of a transcriptional complex composed of three proteins (NF-YA, NF-YB and NF-YC) which bind DNA at CCAAT-boxes, a motif present in most eukaryotic promoters. In plants, each subunit is encoded by small gene families, potentially leading to a multitude of heterotrimeric NF-Y complexes. Here, using yeast two hybrid screenings, we identified the MtNF-YB and MtNF-YC subunits that interact with MtNF-YA1 and A2. Further, we confirmed, both in yeast and in planta, the formation of trimeric NF-Y complexes and showed that these complexes are functional during nodulation using reverse genetic approaches and ChIP-PCR. Finally, as orthologs of the characterized NF-Y subunits also control nodulation in other legumes, we showed in common bean that similar NF-Y trimers could form in planta. Our results suggest that we have identified a group of evolutionary conserved NF-Y proteins that interact to control nodulation in leguminous plants.Fil: Baudin, Maël. Centre National de la Recherche Scientifique; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; FranciaFil: Laloum, Tom. Centre National de la Recherche Scientifique; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; FranciaFil: Lepage, Agnes. Centre National de la Recherche Scientifique; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; FranciaFil: Rípodas, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Ariel, Federico Damian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centre D'etudes de Saclay; FranciaFil: Frances, Lisa. Centre National de la Recherche Scientifique; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; FranciaFil: Crespi, Martin. Centre D'etudes de Saclay; FranciaFil: Gamas, Pascal. Centre National de la Recherche Scientifique; FranciaFil: Blanco, Flavio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Zanetti, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: de Carvalho-Niebel, Fernanda. Centre National de la Recherche Scientifique; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; FranciaFil: Niebel, Andreas. Centre National de la Recherche Scientifique; Francia. Centre de Recherche de Nantes. Institut National de la Recherche Agronomique; Franci