title: DELLAs regulate chlorophyll and carotenoid biosynthesis to prevent photooxidative damage during seedling deetiolation in Arabidopsis.
abstract: In plants, light represents an important environmental signal that triggers the production of photosynthetically active chloroplasts. This developmental switch is critical for plant survival because chlorophyll precursors that accumulate in darkness can be extremely destructive when illuminated. Thus, plants have evolved mechanisms to adaptively control plastid development during the transition into light. Here, we report that the gibberellin (GA)-regulated DELLA proteins play a crucial role in the formation of functional chloroplasts during deetiolation. We show that Arabidopsis thaliana DELLAs accumulating in etiolated cotyledons derepress chlorophyll and carotenoid biosynthetic pathways in the dark by repressing the transcriptional activity of the phytochrome-interacting factor proteins. Accordingly, dark-grown GA-deficient ga1-3 mutants (that accumulate DELLAs) display a similar gene expression pattern to wild-type seedlings grown in the light. Consistent with this, ga1-3 seedlings accumulate higher amounts of protochlorophyllide (a phototoxic chlorophyll precursor) in darkness but, surprisingly, are substantially more resistant to photooxidative damage following transfer into light. This is due to the DELLA-dependent upregulation of the photoprotective enzyme protochlorophyllide oxidoreductase (POR) in the dark. Our results emphasize the role of DELLAs in regulating the levels of POR, protochlorophyllide, and carotenoids in the dark and in protecting etiolated seedlings against photooxidative damage during initial light exposure.
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Unité Propre de Recherche 2357, Conventioné avec l'Université de Strasbourg, Strasbourg, France.
authors.forename: Soizic
authors.initials: S
authors.lastname: Cheminant
authors.forename: Michael
authors.initials: M
authors.lastname: Wild
authors.forename: Florence
authors.initials: F
authors.lastname: Bouvier
authors.forename: Sandra
authors.initials: S
authors.lastname: Pelletier
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Renou
authors.forename: Mathieu
authors.initials: M
authors.lastname: Erhardt
authors.forename: Scott
authors.initials: S
authors.lastname: Hayes
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Terry
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Patrick
authors.initials: P
authors.lastname: Achard
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism* / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism* / Q000528:radiation effects; D018548:Cotyledon / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D008027:Light; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism*; D038761:Photobleaching; D010834:Phytochrome / Q000378:metabolism; D011521:Protochlorophyllide / Q000378:metabolism / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D029681:Arabidopsis Proteins; D005875:Gibberellins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D010834:Phytochrome; D002734:Chlorophyll; D011521:Protochlorophyllide; D002338:Carotenoids; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase