Roles of Defense Hormones in the Regulation of Ozone-Induced Changes in Gene Expression and Cell Death.
Apoplast, the diffusional space between plant cell plasma membranes, is an important medium for signaling within and between the cells. Apoplastic reactive oxygen species (ROS) are crucial signaling molecules in various biological processes. ROS signaling is interconnected with the response to several hormones, including jasmonic acid (JA), salicylic acid (SA) and ethylene. Using ozone (O3) to activate apoplastic ROS signaling, we performed global and targeted analysis of transcriptional changes and cell death assays to dissect the contribution of hormone signaling and various transcription factors (TFs) in the regulation of gene expression and cell death. The contributions of SA, JA, and ethylene were assessed through analysis of single, double, and triple mutants deficient in biosynthesis or signaling for all three hormones. Even in the triple mutant, the global gene expression responses to O3 were mostly similar to the wild-type. Cell death in the JA receptor mutant coi1-16 was suppressed by impairment of the NADPH oxidase RBOHF, suggesting a role for a ROS signal in limiting the spread of cell death. In response to apoplastic ROS, there is not a single signaling pathway that regulates gene expression or cell death. Instead, several pathways regulate the apoplastic ROS response via combinatorial or overlapping mechanisms.
Division of Plant Biology, Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, PO Box 65 Viikinkaari 1, 00014 Helsinki, Finland.
Enjun
E
Xu
Division of Plant Biology, Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, PO Box 65 Viikinkaari 1, 00014 Helsinki, Finland.
Lauri
L
Vaahtera
Division of Plant Biology, Department of Biosciences, Viikki Plant Science Centre, University of Helsinki, PO Box 65 Viikinkaari 1, 00014 Helsinki, Finland; Institute of Technology, University of Tartu, Nooruse 1, Tartu 50411, Estonia. Electronic address: mikael.brosche@helsinki.fi.
Mikael
M
Brosché
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D003517:Cyclopentanes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D054883:Oxylipins / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D010126:Ozone; C011006:jasmonic acid; D020156:Salicylic Acid
cell death; ethylene; gene expression; jasmonic acid; reactive oxygen species; salicylic acid