caa a22 4500 397522290 CHVBK 20180308164636.0 cr unu---uuuuu 161202e199510 xx s 000 0 eng 10.1093/jxb/46.10.1479 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.10.1479 Phosphorus deficiency increases the acetylene-induced decline in nitrogenase activity in soybean (Glycine max (L.) Merr.) [Elektronische Daten] [Jérôme Ribet, Jean-Jacques Drevon] Open-flow assays of acetylene reduction activity {ARA)and CO2 production in nodulated roots were performed in situ with soybean {Glycine max (L.) Merr.) cv. Kingsoy grown hydroponically with orthophosphate (Pi) nutrition either limiting (low-P) or non-limiting (control) for plant growth. Nodule growth was more limited than shoot growth by P deficiency. During ARA assays, nitrogenase activity declined a few minutes after exposure of the nodulated roots to C2H2, and this acetyleneinduced decline (C2H2-ID) was twice as intense at low-P. Moreover, the minimum ARA after the C2H2-ID was reached about 10 min earlier at low-P. The intensity of the C2H2-ID was correlated negatively with nodule mass per plant and positively with the ratio of shoot/nodule mass. After initial exposure to C2H2, the nodulated-root CO2 production was transiently stimulated and, moreover, this increase was 2-fold higher at low-P. Then, the nodulated-root CO2 production decreased with nodule C2H4 production. During the C2H2-ID, the nodule nitrogenase-linked respiration, which was computed as the variable component of the linear regression between CO2 and C2H4 production, was 2-fold higher at low-P. Furthermore, the microscopic observation of nodule sections revealed that starch deposits were decreased at low-P. However, nitrogenase activity, i.e. ARA before the C2H2-ID, was not affected by P deficiency. It is argued that P deficiency increased the C2H2-ID because it increased nodule permeability to O2 diffusion. © Oxford University Press Research Papers nationallicence Acetylene reduction nationallicence nitrogen fixation nationallicence phosphorus nationallicence respiration nationallicence soybean nationallicence Glycine max (L.) Merr nationallicence Ribet Jérôme Laboratoire de Recherche sur les Symbiotes des Racines, INRA, Place Viala, F-34 060 Montpellier cedex, France aut Drevon Jean-Jacques Laboratoire de Recherche sur les Symbiotes des Racines, INRA, Place Viala, F-34 060 Montpellier cedex, France aut Journal of Experimental Botany Oxford University Press 46/10(1995-10), 1479-1486 0022-0957 46:10<1479 1995 46 exbotj https://doi.org/10.1093/jxb/46.10.1479 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.10.1479 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ribet Jérôme Laboratoire de Recherche sur les Symbiotes des Racines, INRA, Place Viala, F-34 060 Montpellier cedex, France aut NATIONALLICENCE 700 1- Drevon Jean-Jacques Laboratoire de Recherche sur les Symbiotes des Racines, INRA, Place Viala, F-34 060 Montpellier cedex, France aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/10(1995-10), 1479-1486 0022-0957 46:10<1479 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford