科研之友
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摘要
Nitric oxide (NO) is a reactive gaseous molecule recognized as biological mediator in all leaving organisms. Although there is a lot of evidences on both enzymatic and nonenzymatic synthesis of NO in plant cells, this problem still remains puzzling. NO is generated in different cellular compartments from L-arginine or nitrite ions in reaction catalyzed by nitric oxide synthase or nitrate reductase, respectively. Recent experimental data have shown NO involvement in regulation of many different physiological processes in plants such as seed germination, flowering, root rhizogenesis or senescence. NO acts as signaling molecule in plant reaction to biotic (pathogen attack) and abiotic stresses (heavy metals, salinity, drought, hypoxia). NO itself not only participate in signal transduction but also modifies cellular components, mainly proteins through cysteine S-nitrosylation and probably tyrosine nitration. The involvement of NO into regulation of so many responses implies a severe mechanism of regulation of its concentration in the tissue. A number of reports implicated non-symbiotic hemoglobins as a key system for modulation of NO bioactivity in plants, especially during low oxygen support. Plant hemoglobins with properties distinct from symbiotic hemoglobin are expressed in different organs and tissue and are widespread in the plant kingdom. Hemoglobins are suggested to protect plant cells against nitrosative stress resulting from enhanced reactive nitrogen species production and to modify NO signaling action. The aim of the paper is to explain the main physiological and biochemical functions reported for nonsymbiotic hemoglobins in plants and characterize the mechanism by which hemoglobins interact with NO in plants exposed to low oxygen conditions. The function of hemoglobin/nitric oxide cycle is described as the way of restoration redox and energy status of the cells.
- 出版日期2009
