Abstract
Ascorbate oxidase is an apoplastic enzyme in plants which catalyzes the oxidation of ascorbate to monodehydroascorbate. Its biological function remains largely unclear. Transgenic tobacco plants expressing AAO gene in sense and antisense orientations and an Arabidopsis mutant were used to examine the potential roles of AAO for salt-stress tolerance in plants. AAO activities in the transgenic tobacco plants expressing AAO gene in sense and antisense orientations were about 16-fold and 0.2-fold of wild-type's ones. Under high salinity condition, the germination yields were highest in antisense plants, then wild-type and sense plants followed. When tobacco plants were subjected to salt stress during the developmental- and reproductive-stage, the sense plants were most severely damaged whereas the antisense plants exhibited the modest inhibition. Number of ovaries and seed weight was high in the antisense plants, but significantly reduced in the sense plants. These results will be presented.
