Abstract
In legume nodules, treatments such as detopping or nitrate fertilization inhibit nodule metabolism and N2 fixation by decreasing the nodule's permeability to O2 diffusion, thereby decreasing the infected cell O2 concentration (Oi) and increasing the degree to which nodule metabolism is limited by O2 availability. In the present study we used nodule oximetry to assess and compare the role of O2 limitation in soybean (Glycine max L. Merr) nodules inhibited by either drought or detopping. Compared to detopping, drought caused only minor decreases in Oi, and when the external O2 concentration was increased to raise Oi, the infected cell respiration rate in the drought-stressed plants was not stimulated as much as it was in the nodules of the detopped plants. Unlike those in detopped plants, nodules exposed to moderate drought stress displayed an O2-sufficient respiration rate that was significantly lower than that in control nodules. Despite possible side effects of oximetry in altering nodule metabolism, these results provided direct evidence that, compared to detopping, O2 limitation plays a minor role in the inhibition of nodule metabolism during drought stress and changes in nodule permeability are the effect, not the cause, of a drought-induced inhibition of nodule metabolism and the O2-suffiecient rate of respiration.
Full Text
The Full Text of this article is available as a PDF (862.5 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Del Castillo L. D., Hunt S., Layzell D. B. The Role of Oxygen in the Regulation of Nitrogenase Activity in Drought-Stressed Soybean Nodules. Plant Physiol. 1994 Nov;106(3):949–955. doi: 10.1104/pp.106.3.949. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Denison R. F., Hunt S., Layzell D. B. Nitrogenase activity, nodule respiration, and o(2) permeability following detopping of alfalfa and birdsfoot trefoil. Plant Physiol. 1992 Mar;98(3):894–900. doi: 10.1104/pp.98.3.894. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Denison R. F., Layzell D. B. Measurement of legume nodule respiration and o(2) permeability by noninvasive spectrophotometry of leghemoglobin. Plant Physiol. 1991 May;96(1):137–143. doi: 10.1104/pp.96.1.137. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Denison R. F., Witty J. F., Minchin F. R. Reversible o(2) inhibition of nitrogenase activity in attached soybean nodules. Plant Physiol. 1992 Dec;100(4):1863–1868. doi: 10.1104/pp.100.4.1863. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gibson Q. H., Wittenberg J. B., Wittenberg B. A., Bogusz D., Appleby C. A. The kinetics of ligand binding to plant hemoglobins. Structural implications. J Biol Chem. 1989 Jan 5;264(1):100–107. [PubMed] [Google Scholar]
- Guerin V., Trinchant J. C., Rigaud J. Nitrogen Fixation (C(2)H(2) Reduction) by Broad Bean (Vicia faba L.) Nodules and Bacteroids under Water-Restricted Conditions. Plant Physiol. 1990 Mar;92(3):595–601. doi: 10.1104/pp.92.3.595. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Khanna-Chopra R., Koundal K. R., Sinha S. K. A Simple Technique of Studying Water Deficit Effects on Nitrogen Fixation in Nodules without Influencing the Whole Plant. Plant Physiol. 1984 Sep;76(1):254–256. doi: 10.1104/pp.76.1.254. [DOI] [PMC free article] [PubMed] [Google Scholar]
- King B. J., Hunt S., Weagle G. E., Walsh K. B., Pottier R. H., Canvin D. T., Layzell D. B. Regulation of o(2) concentration in soybean nodules observed by in situ spectroscopic measurement of leghemoglobin oxygenation. Plant Physiol. 1988 Jun;87(2):296–299. doi: 10.1104/pp.87.2.296. [DOI] [PMC free article] [PubMed] [Google Scholar]
- King B. J., Layzell D. B. Effect of Increases in Oxygen Concentration during the Argon-Induced Decline in Nitrogenase Activity in Root Nodules of Soybean. Plant Physiol. 1991 Jun;96(2):376–381. doi: 10.1104/pp.96.2.376. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuzma M. M., Hunt S., Layzell D. B. Role of Oxygen in the Limitation and Inhibition of Nitrogenase Activity and Respiration Rate in Individual Soybean Nodules. Plant Physiol. 1993 Jan;101(1):161–169. doi: 10.1104/pp.101.1.161. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thumfort P. P., Atkins C. A., Layzell D. B. A Re-Evaluation of the Role of the Infected Cell in the Control of O2 Diffusion in Legume Nodules. Plant Physiol. 1994 Aug;105(4):1321–1333. doi: 10.1104/pp.105.4.1321. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walsh K. B., Vessey J. K., Layzell D. B. Carbohydrate supply and n(2) fixation in soybean : the effect of varied daylength and stem girdling. Plant Physiol. 1987 Sep;85(1):137–144. doi: 10.1104/pp.85.1.137. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weisz P. R., Denison R. F., Sinclair T. R. Response to drought stress of nitrogen fixation (acetylene reduction) rates by field-grown soybeans. Plant Physiol. 1985 Jul;78(3):525–530. doi: 10.1104/pp.78.3.525. [DOI] [PMC free article] [PubMed] [Google Scholar]