title: G protein-coupled receptor-type G proteins are required for light-dependent seedling growth and fertility in Arabidopsis.
abstract: G protein-coupled receptor-type G proteins (GTGs) are highly conserved membrane proteins in plants, animals, and fungi that have eight to nine predicted transmembrane domains. They have been classified as G protein-coupled receptor-type G proteins that function as abscisic acid (ABA) receptors in Arabidopsis thaliana. We cloned Arabidopsis GTG1 and GTG2 and isolated new T-DNA insertion alleles of GTG1 and GTG2 in both Wassilewskija and Columbia backgrounds. These gtg1 gtg2 double mutants show defects in fertility, hypocotyl and root growth, and responses to light and sugars. Histological studies of shoot tissue reveal cellular distortions that are particularly evident in the epidermal layer. Stable expression of GTG1(pro):GTG1-GFP (for green fluorescent protein) in Arabidopsis and transient expression in tobacco (Nicotiana tabacum) indicate that GTG1 is localized primarily to Golgi bodies and to the endoplasmic reticulum. Microarray analysis comparing gene expression profiles in the wild type and double mutant revealed differences in expression of genes important for cell wall function, hormone response, and amino acid metabolism. The double mutants isolated here respond normally to ABA in seed germination assays, root growth inhibition, and gene expression analysis. These results are inconsistent with their proposed role as ABA receptors but demonstrate that GTGs are fundamentally important for plant growth and development.
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom.
authors.forename: Felix W
authors.initials: FW
authors.lastname: Jaffé
authors.forename: Gian-Enrico C
authors.initials: GE
authors.lastname: Freschet
authors.forename: Billy M
authors.initials: BM
authors.lastname: Valdes
authors.forename: John
authors.initials: J
authors.lastname: Runions
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Terry
authors.forename: Lorraine E
authors.initials: LE
authors.lastname: Williams
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005298:Fertility; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018525:Germination; D006056:Golgi Apparatus / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D011058:Pollen / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D043562:Receptors, G-Protein-Coupled; D000040:Abscisic Acid; C534590:GTG1 protein, Arabidopsis; C534591:GTG2 protein, Arabidopsis