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The acetylene-induced decline in nitrogenase activity in root nodules of Elaeagnus angustifolia

The acetylene-induced decline in nitrogenase activity in root nodules of Elaeagnus angustifolia The rate of C 2 H 2 reduction by nodulated seedlings of Elaeagnus angustifolia (Russian olive) was followed as a function of time. Our goals were to: 1) determine whether there is an C 2 H 2 -induced decline in nitrogenase activity; and 2) investigate the mechanism of any decline. We found a peak rate of C 2 H 2 reduction at 1.5 min after the introduction of C 2 H 2 that was followed by a rapid decline in activity to 56% of the peak value. After the decline there was a partial recovery to 67% of the peak value at 60 min. When the pO 2 was decreased during the decline there was no significant effect (p≤0.05) on nitrogenase activity. When the C 2 H 2 reduction assay was preceded by an incubation in a gas mixture (20 kPa O 2 ) with Ar substituted for N 2 , there was little decline in nitrogenase activity as a function of time, but the rate of C 2 H 2 reduction per gram nodule was reduced by approximately 50%. From these results we conclude that t Elaeagnus angustifolia exhibits a pronounced C 2 H 2 -induced decline and consequently the initial peak rate C 2 H 2 reduction must be determined to obtain a valid measure of nitrogenase activity. We further suggest that cessation of NH 3 formation initiates the decline and that the decline is not caused by a change in nodule permeability to gases. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant and Soil Springer Journals

The acetylene-induced decline in nitrogenase activity in root nodules of Elaeagnus angustifolia

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References (16)

Publisher
Springer Journals
Copyright
Copyright © 1997 by Kluwer Academic Publishers
Subject
Environment; Ecology; Plant Sciences; Plant Physiology; Soil Science & Conservation
ISSN
0032-079X
eISSN
1573-5036
DOI
10.1023/A:1004253714621
Publisher site
See Article on Publisher Site

Abstract

The rate of C 2 H 2 reduction by nodulated seedlings of Elaeagnus angustifolia (Russian olive) was followed as a function of time. Our goals were to: 1) determine whether there is an C 2 H 2 -induced decline in nitrogenase activity; and 2) investigate the mechanism of any decline. We found a peak rate of C 2 H 2 reduction at 1.5 min after the introduction of C 2 H 2 that was followed by a rapid decline in activity to 56% of the peak value. After the decline there was a partial recovery to 67% of the peak value at 60 min. When the pO 2 was decreased during the decline there was no significant effect (p≤0.05) on nitrogenase activity. When the C 2 H 2 reduction assay was preceded by an incubation in a gas mixture (20 kPa O 2 ) with Ar substituted for N 2 , there was little decline in nitrogenase activity as a function of time, but the rate of C 2 H 2 reduction per gram nodule was reduced by approximately 50%. From these results we conclude that t Elaeagnus angustifolia exhibits a pronounced C 2 H 2 -induced decline and consequently the initial peak rate C 2 H 2 reduction must be determined to obtain a valid measure of nitrogenase activity. We further suggest that cessation of NH 3 formation initiates the decline and that the decline is not caused by a change in nodule permeability to gases.

Journal

Plant and Soil – Springer Journals

Published: Apr 1, 1997

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