A pharmacological and mutagenic approach to dissecting the response of Arabidopsis thaliana to ozone

North, Kathryn A. and Knight, Marc R. and Hetherington, Alistair and McAinsh, Martin (2003) A pharmacological and mutagenic approach to dissecting the response of Arabidopsis thaliana to ozone. In: Plant Biology 2003, 2003-07-25 - 2003-07-30.

Abstract

The pollutant tropospheric ozone can cause reductions in crop yield and damage to forests. Ozone and other reactive oxygen species (ROS) derived from ozone are implicated in cell death and visible injury in plants. Arabidopsis thaliana transformed with the photoprotein apoaequorin have been used to investigate changes in cytosolic free calcium [Ca2+]cyt following exposure to ozone. Ozone causes elevations in [Ca2+]cyt in a dose dependent manner inducing a characteristic ‘calcium signature’. This consists of an initial peak in calcium of short duration followed by a second prolonged increase. The amplitude and duration of the second phase of [Ca2+]cyt elevations increase with ozone concentration. Ozone and other oxidative stresses initiate plant defence responses, however the signalling pathways involved are poorly understood. Here a pharmacological analysis of the initiation of the calcium signature and subsequent induction of antioxidant gene glutathione-S-transferase tau 5 (GSTU5) in response to ozone has been undertaken. The calcium specific inhibitors lanthanum and ruthenium red and the calcium chelator EGTA have been used prior to fumigation with ozone. In each case the calcium signature was altered, with a reduction in the first and second phase of calcium release. Inhibitors of other signalling molecules and components of signalling pathways have also been used. Additionally to further our understanding of the sources of calcium involved in the adaptive response of plants to ozone a mutagenic approach has also been undertaken. The calcium transport mutant ACA3, also transformed with apoaequorin, was treated with ozone to establish whether disruption of calcium transport within the plasma membrane affects the plant’s ability to respond to ozone.