title: Analysis of oxidative signalling induced by ozone in Arabidopsis thaliana.
abstract: We are using acute ozone as an elicitor of endogenous reactive oxygen species (ROS) to understand oxidative signalling in Arabidopsis. Temporal patterns of ROS following a 6 h exposure to 300 nL L(-1) of ozone in ozone-sensitive Wassilewskija (Ws-0) ecotype showed a biphasic ROS burst with a smaller peak at 4 h and a larger peak at 16 h. This was accompanied by a nitric oxide (NO) burst that peaked at 9 h. An analysis of antioxidant levels showed that both ascorbate (AsA) and glutathione (GSH) were at their lowest levels, when ROS levels were high in ozone-stressed plants. Whole genome expression profiling analysis at 1, 4, 8, 12 and 24 h after initiation of ozone treatment identified 371 differentially expressed genes. Early induction of proteolysis and hormone-responsive genes indicated that an oxidative cell death pathway was triggered rapidly. Down-regulation of genes involved in carbon utilization, energy pathways and signalling suggested an inefficient defense response. Comparisons with other large-scale expression profiling studies indicated some overlap between genes induced by ethylene and ozone, and a significant overlap between genes repressed by ozone and methyl jasmonate treatment. Further, analysis of cis elements in the promoters of ozone-responsive genes also supports the view that phytohormones play a significant role in ozone-induced cell death.
authors.affiliation: Oklahoma State University, Stillwater, OK, USA. mali@biochem.okstate.edu
authors.forename: Ramamurthy
authors.initials: R
authors.lastname: Mahalingam
authors.forename: Niranjani
authors.initials: N
authors.lastname: Jambunathan
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Gunjan
authors.forename: Enock
authors.initials: E
authors.lastname: Faustin
authors.forename: Hua
authors.initials: H
authors.lastname: Weng
authors.forename: Patricia
authors.initials: P
authors.lastname: Ayoubi
mesh_terms: D017360:Arabidopsis / Q000187:drug effects*; D001205:Ascorbic Acid / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D005651:Fumigation; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D005978:Glutathione / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010126:Ozone / Q000494:pharmacology*; D010447:Peptide Hydrolases / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D010937:Plant Growth Regulators; D014157:Transcription Factors; D009569:Nitric Oxide; D010126:Ozone; D010447:Peptide Hydrolases; D005978:Glutathione; D001205:Ascorbic Acid