Effect of sulfur dioxide hydrates on cell cycle, sister chromatid exchange, and micronuclei in barley.

The effects of sulfur dioxide (SO(2)) hydrates exposure on cell cycle, sister chromatid exchange (SCE), and micronuclei (MN) were investigated in barley (Hordeum vulgare) roots. A mixture of sodium bisulfite and sodium sulfite (1:3), at various concentrations from 1x10(-5) to 3x10(-2)M, was used for the treatments. The results showed that the mixture induced the formation of SCE and MN in barley root cells with different effective concentrations and with different trends as treatment concentrations increased. At high concentrations of 0.5-30.0mM, SO(2) hydrates inhibited the mitotic activity and the growth of barley roots by cell cycle delay and cell death, but at 0.1mM, the chemicals slightly stimulated mitotic activity and root growth. These remarkable effects in causing DNA damage and consequent chromosome damage suggest that SO(2) is genotoxic agent and its genotoxicity may influence the mitotic activity and plant growth under SO(2) stress.