title: Evidence from inhibitor studies that the endophyte synthesises nitrogenase in the root nodules of Alnus glutinosa L. Gaertn.
abstract: Nitrogenase activity (acetylene reduction assay) in the nodulated non-leguminous angiosperm Alnus glutinosa is inhibited within minutes when plants are exposed to a gas phase containing 90% oxygen On returning the plants to air, nitrogenase activity recovers within a few hours, both in the presence of cycloheximide, which inhibits protein synthesis on 80 S (eukaryotic) ribosomes, and in the absence of inhibitor. When chloramphenicol, which inhibits protein synthesis on 70 S (prokaryotic) ribosomes, is added instead of cycloheximide, recovery from oxygen inhibition does not occur, or occurs only slowly. The effects of chloramphenicol are specific to the D-threo-isomer which indicates a direct inhibition of protein synthesis. Erythromycin has a similar effect to chloramphenicol. Protein biosynthesis in non-nodulated roots is inhibited by cycloheximide but not by chloramphenicol. The results are interpreted as evidence that the nitrogenase within Alnus glutinosa root nodules is synthesised by the microbial symbiont.
authors.affiliation: Department of Biological Sciences, University of Dundee, DD1 4HN, Dundee, U.K..
authors.forename: R A
authors.initials: RA
authors.lastname: Skeffington
authors.forename: W D
authors.initials: WD
authors.lastname: Stewart