Phosphorous deficiency decreases nitrogenase activity but increases proton efflux in N 2-fixing Medicago truncatula

• Published in: Plant physiology and biochemistry Vol. 49; no. 4; pp. 458 - 460
• Main Authors: Schulze, J., Mohamed, M.A.N., Carlsson, G., Drevon, J.J.
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 2011; Elsevier
• Subjects: Agricultural Science; Agricultural sciences; Jordbruksvetenskap; Life Sciences; Model legume; Nitrogen fixation; P deficiency; Sinorhizobium meliloti; Symbiosis; Symbiosis; Nitrogen fixation; P deficiency; Sinorhizobium meliloti; Model legume; symbiotic n-2 fixation; release; nodules; rhizobium-meliloti; phaseolus-vulgaris; alfalfa; plants; induced; decline
• ISSN: 0981-9428; 1873-2690; 1873-2690
• DOI: 10.1016/j.plaphy.2011.01.022

Effects of Sinorhizobium strain and P nutrition on N 2-dependent growth, nitrogenase activity and proton efflux by nodulated roots were investigated in the model legume Medicago truncatula cultivar Jemalong grown in hydroaeroponic culture in symbioses with Sinorhizobium meliloti strains 102F51 and 2011. Sinorhizobium strain had strong effects on nitrogenase activity and N 2-dependent growth, with S. meliloti 102F51 being the more efficient strain. Apparent and total nitrogenase activities, measured by hydrogen evolution in air and argon, respectively, were drastically reduced in plants supplied with 5 μmol P plant −1 week −1 as compared with 15 μmol P plant −1 week −1. There was a net proton efflux as soon as 2 weeks after inoculation and, in contrast to the effect of P nutrition on nitrogenase activity, P deficiency increased total and specific proton effluxes, irrespective of Sinorhizobium strain. ► We measured N 2-dependent growth in the model legume Medicago truncatula cv Jemalong. ► The Sinorhizobium meliloti strains 120F51 was more efficient than S. meliloti 2011. ► Nitrogenase activity was drastically reduced in plants grown under P deficiency. ► P deficiency increased proton effluxes, irrespective of Sinorhizobium strain.