A mechanism for promoting the germination of Zinnia elegans seeds by hydrogen peroxide

H2O2 promotes seed germination of cereal plants such as barley, wheat and rice, and several mechanisms have been proposed for its action [Naredo et al. (1998) Seed Sci Technol, 26: 675-689], We investigated the role of H2O2 in the germination of Zinnia elegans seeds. H2O2 promoted seed germination in a dose-dependent manner as did respiratory inhibitors, indicating that H2O2 itself possibly promotes seed germination rather than O-2. Seed germination was promoted by removal of pericarp from seeds or by removal of ethanol-soluble compounds from the seeds with pericarp, The ethanol-soluble compounds suppressed the germination of seeds having no pericarp, and this effect was reversed by H2O2. These findings indicate that oxidation of the germination inhibitor(s) present in the pericarp by H2O2 promotes seed germination. Antioxidants which are derivatives of well-known germination inhibitors suppressed seed germination in a dose-dependent manner, suggesting that, to initiate seed germination, a germination inhibitor(s) should be decomposed by an oxidant such as H2O2.