Abstract
Plants are exposed to various environmental stressors associated with generation of reactive oxygen species (ROS). To remove ROS, plants synthesize antioxidant substances such as ascorbate (ASA). The leaf injury under ozone exposure in the ASA-deficient Arabidopsis mutant (vtc1) has been explained by the ROS generation. However, recent studies showed that pathogen-infected vtc1 accumulates higher levels of salicylic acid (SA) glucoside, indicating not only the ROS generation but also phytohormone-pathways are involved in the processes leading to the leaf injury. In the present study, we focused on two phytohormones, SA and ethylene. Accumulation of these phytohormones was higher in vtc1 than in Col-0 under ozone exposure. The transcript levels of PR-1 and PR-4 were also higher in vtc1. These results indicate that the leaf injury in vtc1 arises not only from the ROS generation but also from the accumulation of SA and/or ethylene. Analyses of double mutants vtc1/sid2, vtc1/ein2 are underway.
