Abstract
To understand the plant responses to ozone, we isolated and characterized an ozone sensitive mutant (ozs1) from Arabidopsis thaliana ecotype Columbia. The mutant plants showed enhanced sensitivity to ozone, desiccation and sulfur dioxide but had normal sensitivity to hydrogen peroxide, low temperature and high light intensity. The OZS1 encodes a transporter-like protein in the tellurite resistance/C4-dicarboxylate transporter family. Transpiration levels of OZS1, stomatal conductance and stomatal apertures were greater in ozs1 plants than in wild-type. The stomatal apertures of ozs1 plants showed diurnal fluctuations but were always larger than that of the wild-type plants under the same conditions. The stomata of ozs1 and wild-type plants similarly responded to stimuli such as light, abscisic acid and high concentration (1,000 ppm) of carbon dioxide. These results suggest that OZS1 helps to maintain stomata in the closed state rather than being involved in regulation of responses to these stimuli.
