Abstract
Four novel and single-recessive O3-tolerant mutants, toz (tolerant to ozone) 1, toz2, toz3 and toz4, were isolated from 60,000 EMS-treated seeds of Arabidopsis (Cvi-0). Observation of visible injury as well as ion-leakage analysis demonstrated clear differences between mutants and Cvi-0. Induction of AtGST3, which is regard as a marker for generation of reactive oxygen species (ROS), in mutants was lower than in Cvi-0, suggesting that generation of ROS in mutants was low-level. Moreover, two of them (toz2 and toz3) showed characteristic gene expression patterns induced by O3 and used for further analysis. In toz3, O3-induced expression of AtVSP1, a jasmonate-inducible gene, was remarkable, and the MeJA-induced inhibition of root elongation was higher than the other mutants and Cvi-0. Thus, O3-tolerance in toz3 might be occurred increasing JA-sensitivity because JA signaling modulates O3-induced leaf injury. The toz3 showed constitutive expression of PR-1, indicating that TOZ3 may regulate O3-sensitivity through SA-mediated pathway.
