科研之友
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摘要
Heavy metal stress affects both, nodulation and nitrogen fixation of legumes. Mercury triggers disturbances in cellular structure and metabolism but its influence on ROS generation is poorly understood. Copper is redox active metal which in opposition to mercury is an essential micronutrient for plants. Excess of copper is cytotoxic, as it participates in ROS generation via Fenton-type reaction. %26lt;br%26gt;The present work describes changes in hydrogen peroxide (H2O2) accumulation in response to monthly stress caused by mercury (6 mg/L HgCl2) or copper (60 mg/L CuCl2) in root nodules. %26lt;br%26gt;H2O2 accumulation viewed with a light microscopy was detected by the use of diaminobenzidine (DAB). 2%26apos;,7%26apos;-Dichlorofluorescein diacetate (H2DCF-DA) was used as a probe for the intracellular localization of H2O2 with a confocal laser scanning system. H2O2 detection under transmission electron microscopy was performed by the use of cerium method. %26lt;br%26gt;Histochemical localization and light and confocal microscopy investigations revealed that under Hg or Cu treatments distinct amount of H2O2 accumulated mainly in the interzone and nitrogen-fixing zone. Under normal conditions H2O2 accumulated predominantly in the interzone. Electron microscopy observations showed H2O2 accumulation under Hg or Cu- treatments around peribacteroid membranes of mature symbiosomes located within nitrogen-fixing zone. It should be underlined that under normal conditions H2O2 was not detected at the peribacteroid membranes. %26lt;br%26gt;The main result of our observations is increased accumulation of H2O2 in response to mercury and copper treatments at the peribacteroidal membranes, to our knowledge shown for the first time. Therefore, our results revealed that an overproduction of H2O2 in response to copper or mercury-treatment may account for lowering of nitrogen fixation rates in heavy-metal affected root nodules.
- 出版日期2013-10
