INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
PHYSIOLOGICAL AND TRANSCRIPTIONAL VARIATION OF GENETICALLY DIVERSE ACCESSIONS OF Phaseolus vulgaris IN RESPONSE TO STRAINS OF Rhizobium etli REPRESENTATIVE OF MESOMERICAN AND ANDEAN SOILS
LUCÍA MAZZIOTTA, CAROLINA RÍPODAS, MARINA BATTAGLIA, MARIO AGUILAR, FLAVIO BLANCO, MARÍA EUGENIA ZANETTI
Congreso; Reunión Argentina de Fisiología Vegetal; 2010
Sociedad Argentina de Fisiología vegetal
Phaseolus vulgaris is native to America, where two major centers of genetic diversification (GD) have been proposed, one in Mesoamerica and the other in the Andean region. This legume associates with its symbiotic partner Rhizobium etli to form nitrogen fixing root nodules. In this interaction, host-dependant competitiveness has been observed: plants from the Mesoamerican GD center can effectively recognize and select rhizobium strains that have coevolved in the same geographic region. Here, we investigated the nodulation performance and transcriptional responses of wild and cultivated accessions from each GD center upon inoculation with R. etli strains representative from Mesoamerican and Andean soils, strains SC15 and 55N1 respectively. Accessions from Mesoamerica were more efficiently nodulated by the strain SC15 than the 55N1, whereas accession from the Andean center formed a higher number of nodules when inoculated with the strain 55N1 than SC15. Interestingly, these differences in nodulation performance were higher in cultivated than in wild accessions for each GD center, suggesting that the domestication process might have favored preference for native strains. Transcriptional response of early nodulation (ENOD) genes was explored in these bean accessions by RT-qPCR. Transcripts of PvENOD40, which is required for initiation and development of nodules, accumulated at a similar extent upon inoculation of Andean and Mesomerican roots with either SC15 or 55N1. Interestingly, expression analysis of two transcription factors (TFs) required for both bacterial infection and nodule organogenesis, PvERN and PvNF-YC, revealed that these genes are specifically induced in Mesoamerican accessions inoculated with strain SC15, but not with 55N1. On the other hand, in Andean accessions, neither of these two TFs showed a significant differential behavior between strains SC15 and 55N1. These results indicate that distinct mechanisms for regulation of these two TFs operate in Mesomerican and Andean bean accessions. Further characterization of these regulatory mechanisms would help to understand the molecular basis of functional compatibility in legume-rhizobia symbiosis, which could be use to improve nitrogen fixation in agricultural systems.