Abstract
Cell death in plants caused by ozone is promoted by ethylene and salicylic acid, while reduced by jasmonate (JA). Using ozone-sensitive jasmonate-semi-insensitive Arabidopsis mutant oji1, it has been suggested that JA suppresses cell death by inhibition of ozone-induced ethylene production. On the other hand, ascorbate (AsA) protects cells from direct oxidation by removing active oxygen species. In wild type Ws-2 and oji1, ascorbate contents increased during ozone exposure in spite of visible injury, while sulfur dioxide gas exposure decreased ascorbate contents. From these, it is inferred that sulfur dioxide causes cell death by direct oxidation while ozone induces both programmed cell death and antioxidative function in surviving cells. Treatment with methyl jasmonate suppressed the increase in ascorbate contents in wild type. This result suggests that JA-mediated signaling pathway may possibly participate in regulation of ascorbate contents during ozone stress.
