Light promotes the synthesis of lignin through the production of H2O2 mediated by diamine oxidases in soybean hypocotyls

In order to analyze the relationship between polyamine oxidative degradation induced by tight and the lignin synthesis in cell watts, the activities of diamine oxidases and peroxidase, the contents of H2O2. and lignin, and the growth of hypocotyls in soybean [Glycine max (Linn.) Merr.] grown under tight or in darkness were investigated. In comparison with the dark treatment, light irradiation significantly inhibited the growth of soybean hypocotyls and promoted the activities of diamine oxidases and peroxidase as well as the accumulation of H2O2 and lignin. Treatments with the different concentrations of diamine oxidase inhibitors (2-hydroxyethythydrazine and aminoguanidine) under the light condition inhibited diamine oxidase activity, and decreased the contents of H2O2 and lignin. The results provide evidence for the hypothesis that Light irradiation could promote the accumulation of H2O2. and lignin in cell watts by activating polyamine oxidative degradation mediated by diamine oxidases. (C) 2005 Elsevier GmbH. All rights reserved.