title: Singlet oxygen initiates a plastid signal controlling photosynthetic gene expression.
abstract: Retrograde signals from the plastid regulate photosynthesis-associated nuclear genes and are essential to successful chloroplast biogenesis. One model is that a positive haem-related signal promotes photosynthetic gene expression in a pathway that is abolished by the herbicide norflurazon. Far-red light (FR) pretreatment and transfer to white light also results in plastid damage and loss of photosynthetic gene expression. Here, we investigated whether norflurazon and FR pretreatment affect the same retrograde signal. We used transcriptome analysis and real-time reverse transcription-polymerase chain reaction (RT-PCR) to analyse the effects of these treatments on nuclear gene expression in various Arabidopsis (Arabidopsis thaliana) retrograde signalling mutants. Results showed that the two treatments inhibited largely different nuclear gene sets, suggesting that they affected different retrograde signals. Moreover, FR pretreatment resulted in singlet oxygen (1O2) production and a rapid inhibition of photosynthetic gene expression. This inhibition was partially blocked in the executer1executer2 mutant, which is impaired in1O2signalling. Our data support a new model in which a1O2retrograde signal, generated by chlorophyll precursors, inhibits expression of key photosynthetic and chlorophyll synthesis genes to prevent photo-oxidative damage during de-etiolation. Such a signal would provide a counterbalance to the positive haem-related signal to fine tune regulation of chloroplast biogenesis.
authors.affiliation: Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: Mike T
authors.initials: MT
authors.lastname: Page
authors.affiliation: Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: Alex C
authors.initials: AC
authors.lastname: McCormac
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK.
authors.forename: Alison G
authors.initials: AG
authors.lastname: Smith
authors.affiliation: Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.|Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Terry
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology* / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects* / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D018087:Plastids / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D026082:Singlet Oxygen / Q000494:pharmacology*; D045725:Tetrapyrroles / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects
chemical_list: D045725:Tetrapyrroles; D026082:Singlet Oxygen
keywords: chlorophyll synthesis; chloroplast development; photosynthesis; regulation of gene expression; retrograde signalling; singlet oxygen (1O2); tetrapyrroles