Analysis of oxidative signalling induced by ozone in Arabidopsis thaliana.
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.
Mahalingam
Ramamurthy
R
Oklahoma State University, Stillwater, OK, USA. mali@biochem.okstate.edu
Jambunathan
Niranjani
N
Gunjan
Samir Kumar
SK
Faustin
Enock
E
Weng
Hua
H
Ayoubi
Patricia
P
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
D010937:Plant Growth Regulators; D014157:Transcription Factors; D009569:Nitric Oxide; D010126:Ozone; D010447:Peptide Hydrolases; D005978:Glutathione; D001205:Ascorbic Acid