Ibtissem Guefrachi, Marianna Nagymihály, Véronique Gruber, Florian Lamouche, Jamal Ibijbijen, Théophile Kazmierczak, Benoit Alunni, Eva Kondorosi, Peter Mergaert, Mouna Ouadghiri, Quentin Barrière, Institut des Sciences des Plantes de Paris-Saclay (IPS2 (UMR_9213 / UMR_1403)), Institut National de la Recherche Agronomique (INRA)-Université Paris-Sud - Paris 11 (UP11)-Université Paris Diderot - Paris 7 (UPD7)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Intégrative de la Cellule (I2BC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Biological Research Centre [Budapest] (BRC), Hungarian Academy of Sciences (MTA), Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Faculté des Sciences, Université de Genève = University of Geneva (UNIGE), 'Infrastructures en Biologie Sante et Agronomie' (IBiSA), 'Agence Nationale de la Recherche' (ANR) [ANR-10-INSB-04-01], 'Saclay Plant Sciences' [ANR-10-LABX-0040-SPS], Conseil General de l'Essonne, LabEx Saclay Plant Sciences-SPS [ANR-10-LABX-0040-SPS], Universite Paris-Sud, Agence Nationale de la Recherche, Campus France, France-Tunisia 'Comite Mixte de Cooperation Universitaire' (CMCU) [14G0817], LabEx Saclay Plant Sciences-SPS, Lidex Plant Phenotyping and Engineering Pipeline-3P, [ANR-13-BSV7-0013], Université de Genève (UNIGE), Institut National de la Recherche Agronomique (INRA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Saclay-Université Paris-Sud - Paris 11 (UP11), Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), UMR 1403 Institut des Sciences des Plantes de Paris Saclay, Institut National de la Recherche Agronomique ( INRA ) -Université Paris Diderot - Paris 7 ( UPD7 ), Institut de Biologie Intégrative de la Cellule ( I2BC ), Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Hungarian Academy of Sciences, Hungarian Academy of Sciences ( HAS ), Centre National de la Recherche Scientifique ( CNRS ), Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut National de la Recherche Agronomique ( INRA ), Université de Genève ( UNIGE ), Institut National de la Recherche Agronomique (INRA)-Université Paris-Sud - Paris 11 (UP11)-Université Paris Diderot - Paris 7 (UPD7)-Université d'Évry-Val-d'Essonne (UEVE)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay
Legume plants interact with rhizobia to form nitrogen-fixing root nodules. Legume-rhizobium interactions are specific and only compatible rhizobia and plant species will lead to nodule formation. Even within compatible interactions, the genotype of both the plant and the bacterial symbiont will impact on the efficiency of nodule functioning and nitrogen-fixation activity. The model legume Medicago truncatula forms nodules with several species of the Sinorhizobium genus. However, the efficiency of these bacterial strains is highly variable. In this study, we compared the symbiotic efficiency of Sinorhizobium meliloti strains Sm1021, 102F34, and FSM-MA, and Sinorhizobium medicae strain WSM419 on the two widely used M. truncatula accessions A17 and R108. The efficiency of the interactions was determined by multiple parameters. We found a high effectiveness of the FSM-MA strain with both M. truncatula accessions. In contrast, specific highly efficient interactions were obtained for the A17-WSM419 and R108-102F34 combinations. Remarkably, the widely used Sm1021 strain performed weakly on both hosts. We showed that Sm1021 efficiently induced nodule organogenesis but cannot fully activate the differentiation of the symbiotic nodule cells, explaining its weaker performance. These results will be informative for the selection of appropriate rhizobium strains in functional studies on symbiosis using these M. truncatula accessions, particularly for research focusing on late stages of the nodulation process.