title: Singlet oxygen-dependent translational control in the tigrina-d.12 mutant of barley.
abstract: The tigrina (tig)-d.12 mutant of barley is impaired in the negative control limiting excess protochlorophyllide (Pchlide) accumulation in the dark. Upon illumination, Pchlide operates as photosensitizer and triggers singlet oxygen production and cell death. Here, we show that both Pchlide and singlet oxygen operate as signals that control gene expression and metabolite accumulation in tig-d.12 plants. In vivo labeling, Northern blotting, polysome profiling, and protein gel blot analyses revealed a selective suppression of synthesis of the small and large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (RBCSs and RBCLs), the major light-harvesting chlorophyll a/b-binding protein of photosystem II (LHCB2), as well as other chlorophyll-binding proteins, in response to singlet oxygen. In part, these effects were caused by an arrest in translation initiation of photosynthetic transcripts at 80S cytoplasmic ribosomes. The observed changes in translation correlated with a decline in the phosphorylation level of ribosomal protein S6. At later stages, ribosome dissociation occurred. Together, our results identify translation as a major target of singlet oxygen-dependent growth control and cell death in higher plants.
authors.affiliation: Université Joseph Fourier, CERMO, PO Box 53, F-38041 Grenoble Cedex 9, France.
authors.forename: Dhriti
authors.initials: D
authors.lastname: Khandal
authors.forename: Iga
authors.initials: I
authors.lastname: Samol
authors.forename: Frank
authors.initials: F
authors.lastname: Buhr
authors.forename: Stephan
authors.initials: S
authors.lastname: Pollmann
authors.forename: Holger
authors.initials: H
authors.lastname: Schmidt
authors.forename: Stephan
authors.initials: S
authors.lastname: Clemens
authors.forename: Steffen
authors.initials: S
authors.lastname: Reinbothe
authors.forename: Christiane
authors.initials: C
authors.lastname: Reinbothe
mesh_terms: D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D045342:Light-Harvesting Protein Complexes / Q000096:biosynthesis; D009154:Mutation; D010766:Phosphorylation; D010788:Photosynthesis; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D011521:Protochlorophyllide / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases / Q000502:physiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis; D026082:Singlet Oxygen / Q000494:pharmacology*
chemical_list: D045342:Light-Harvesting Protein Complexes; D026082:Singlet Oxygen; D011521:Protochlorophyllide; D019893:Ribosomal Protein S6 Kinases; D012273:Ribulose-Bisphosphate Carboxylase