title: GLK gene pairs regulate chloroplast development in diverse plant species.
abstract: Chloroplast biogenesis is a complex process that requires close co-ordination between two genomes. Many of the proteins that accumulate in the chloroplast are encoded by the nuclear genome, and the developmental transition from proplastid to chloroplast is regulated by nuclear genes. Here we show that a pair of Golden 2-like (GLK) genes regulates chloroplast development in Arabidopsis. The GLK proteins are members of the GARP superfamily of transcription factors, and phylogenetic analysis demonstrates that the maize, rice and Arabidopsis GLK gene pairs comprise a distinct group within the GARP superfamily. Further phylogenetic analysis suggests that the gene pairs arose through separate duplication events in the monocot and dicot lineages. As in rice, AtGLK1 and AtGLK2 are expressed in partially overlapping domains in photosynthetic tissue. Insertion mutants demonstrate that this expression pattern reflects a degree of functional redundancy as single mutants display normal phenotypes in most photosynthetic tissues. However, double mutants are pale green in all photosynthetic tissues and chloroplasts exhibit a reduction in granal thylakoids. Products of several genes involved in light harvesting also accumulate at reduced levels in double mutant chloroplasts. GLK genes therefore regulate chloroplast development in diverse plant species.
authors.affiliation: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Fitter
authors.forename: David J
authors.initials: DJ
authors.lastname: Martin
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Copley
authors.forename: Robert W
authors.initials: RW
authors.lastname: Scotland
authors.forename: Jane A
authors.initials: JA
authors.lastname: Langdale
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D002736:Chloroplasts / Q000502:physiology* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D012275:Oryza / Q000235:genetics / Q000254:growth & development; D010802:Phylogeny; D063245:Plant Development; D010940:Plant Proteins; D010944:Plants / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D003313:Zea mays / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; C468867:GLK1 protein, Arabidopsis; C432461:GLK1 protein, Zea mays; C468868:GLK2 protein, Arabidopsis; C499672:Glk1 protein, Oryza sativa; D008565:Membrane Proteins; D010940:Plant Proteins; D014157:Transcription Factors