Abstract
Sulfur dioxide (SO2) is mainly produced by fossil fuel combustion. (SO2) absorbed by plant leaves dissolves in aqueous phase of apoplast and it yields sulfite ion. Sulfite inhibits photoshynthetic carbon fixation, by competing for carbon dioxide or bicarbonate binding sites of RuBisCO or PEPCase, respectively, and by reacting with thiol groups of several enzymes. Sulfite produces much active oxygen species (AOS) by sulfite-mediated chain reaction in chloroplasts and sulfite itself is oxidized into harmless sulfate. To enhance (SO2)-detoxying capacity of plants, we tried to generate transgenic tobacco with enhanced activities of sulfite oxidase (SOX) by introducing cDNA of rat liver SOX, which oxidizes SO32- to (SO32-) without generating AOS.
Four lines of transgenic tobacco were obtained. By Southern blotting it was confirmed that they have 2 to 5 copies of SOX genes. Transgenic plants showed higher tolerance to sulfite ion than control ones.
