Low antioxidant concentrations impact on multiple signalling pathways in Arabidopsis thaliana partly through NPR1.
Production of reactive oxygen species (ROS) is linked to signalling in both developmental and stress responses. The level of ROS is controlled by both production and removal through various scavengers including ascorbic acid and glutathione. Here, the role of low ascorbic acid or glutathione concentrations was investigated on ozone-induced cell death, defence signalling, and developmental responses. Low ascorbic acid concentrations in vtc1 activated expression of salicylic acid (SA)-regulated genes, a response found to be dependent on the redox-regulated transcriptional co-regulator NPR1. In contrast, low glutathione concentrations in cad2 or pad2 reduced expression of SA-regulated genes. Testing different responses to jasmonic acid (JA) revealed the presence of at least two separate JA signalling pathways. Treatment of the vtc1 mutant with JA led to hyper-induction of MONODEHYDROASCORBATE REDUCTASE3, indicating that low ascorbic acid concentrations prime the response to JA. Furthermore, NPR1 was found to be a positive regulator of JA-induced expression of MDHAR3 and TAT3. The vtc1 and npr1 mutants were sensitive to glucose inhibition of seed germination; an opposite response was found in cad2 and pad2. Overall, low ascorbic acid concentrations mostly led to opposite phenotypes to low glutathione concentrations, and both antioxidants interacted with SA and JA signalling pathways.
Department of Biosciences, University of Helsinki, Helsinki, Finland. mikael.brosche@helsinki.fi
Mikael
M
Brosché
Jaakko
J
Kangasjärvi
D000085:Acetates / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D003517:Cyclopentanes / Q000494:pharmacology; D035264:Flowers / Q000187:drug effects / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D018525:Germination / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D054883:Oxylipins / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology*; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
D000085:Acetates; D000975:Antioxidants; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; C105496:NPR1 protein, Arabidopsis; D054883:Oxylipins; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D010126:Ozone; C072239:methyl jasmonate; D005978:Glutathione; D020156:Salicylic Acid; D001205:Ascorbic Acid