The Role of Oxygen in the Regulation of Nitrogenase Activity in Drought-Stressed Soybean Nodules.
AUTOR(ES)
Del Castillo, L. D.
RESUMO
The aim of this study was to investigate the mechanism of nitrogenase inhibition in drought-stressed soybean (Glycine max L.) nodules to determine whether this stress was similar to other inhibitory treatments (e.g. detopping) known to cause an O2 limitation of nodule metabolism. Nodulated soybean plants were either detopped or subjected to mild, moderate, or severe drought stress by growth in different media and by withholding water for different periods. All treatments caused a decline in nitrogenase activity, and in the drought-stressed nodules, the decline was correlated with more negative nodule water potentials. Increases in rhizosphere O2 concentration stimulated nitrogenase activity much more in detopped plants than in drought-stressed plants, reflecting a greater degree of O2 limitation with the detopped treatment than with the drought-stressed treatment. These results indicated that drought stress differs from many other inhibitory treatments, such as detopping, in that its primary cause is not a decrease in nodule permeability and a greater O2 limitation of nodule metabolism. Rather, drought stress seems to cause a decrease in the maximum O2-sufficient rate of nodule respiration or nitrogenase activity, and the changes in nodule permeability reported to occur in drought-stressed nodules may be a response to elevated O2 concentrations in the infected cell that may occur as nodule respiration declines.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=159617Documentos Relacionados
- Identification of reference genes for expression analysis by real-time quantitative PCR in drought-stressed soybean.
- Role of Oxygen in the Limitation and Inhibition of Nitrogenase Activity and Respiration Rate in Individual Soybean Nodules.
- Bacteroid Proline Catabolism Affects N2 Fixation Rate of Drought-Stressed Soybeans1
- Evidence for the Contribution of the Mehler-Peroxidase Reaction in Dissipating Excess Electrons in Drought-Stressed Wheat.
- Increased susceptibility and reduced phytoalexin accumulation in drought-stressed peanut kernels challenged with Aspergillus flavus.