Resumen de Factores estructurales, bioquímicos y moleculares de la simbiosis "Bradyrhizobium sp. (Lupinus)-Lupinus

M.R. de Felipe Antón, Mercedes Fernández Pascual, M.M. Lucas Sánchez, E. Fedorova, M.P. Golvano Herrero, A. González Sama, L. Guasch Pereira, Cristina de Lorenzo Carretero, Núria de María de las Heras, José Manuel Pozuelo Guanche, J.J. Pueyo Dabad, A. Vivo Rodríguez

• The present revision summarises some of the original works carried out in our Department to study different aspects of the peculiar symbiosis Bradyrhyzobium sp. Lupinus, by integrating structure and function. The first part of the revision is focused to a structural study on the infection mechanisms, since differ of other legumes. This study was realized by applying immunofluorescent techniques with the green fluorescent protein, immunocytochemistry and different microscopies. It could be observed that the infection by the Bradyrhizobium follows the intercellular way. The infection study includes the presence of enzymatic components, as MAPKs (Mitogen-Activated Protein Kinase) and aldehyde oxidase in the first steps of the symbiosis. Both enzymes are very much related with auxins and cell multiplication. The second part takes up the physiological, biochemical and genetic mechanisms that regulates nitrogen fixation, speccially those related to oxygen diffusion, since nitrogenase activity is very sensible to oxygen and needs a microaerobic atmosphere for its function. Between these mechanisms, the leghemoglobine and the oxygendiffusion resistance barrier have been considered the more important in oxygen regulation. Finally it is included the results of a genetic study carried out to know the genes implicated in nodule oxygen diffusion as: lenod 2, leghemoglobin and nifH.