Localization of hydrogen peroxide during the defence response of Arabidopsis thaliana against the plant-parasitic nematode Heterodera glycines

Hydrogen peroxide (H2O2) production during the infection of Arabidopsis tha liana by the soybean cyst nematode Heterodera glycines was detected histoch emically by the reaction of H2O2 with cerium chloride producing four differ ent patterns of electron-dense precipitates of cerium perhydroxides. As A. thaliana is not a regular host of H. glycines, the defence response is cons iderable, but does not completely inhibit the development of the nematode. H2O2 was produced not only by cells mechanically damaged during invasion an d feeding site induction by the nematode, but also by cells surrounding dev eloping syncytia and cells which were neither in contact with the nematode nor with the syncytium.