A correlative study of hydrogen peroxide accumulation after mercury or copper treatment observed in root nodules of Medicago truncatula under light, confocal and electron microscopy

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.