title: Overexpression of the heterotrimeric G-protein alpha-subunit enhances phytochrome-mediated inhibition of hypocotyl elongation in Arabidopsis.
abstract: Plant heterotrimeric G-proteins have been implicated in a number of signaling processes. However, most of these studies are based on biochemical or pharmacological approaches. To examine the role of heterotrimeric G-proteins in plant development, we generated transgenic Arabidopsis expressing the Galpha subunit of the heterotrimeric G-protein under the control of a glucocorticoid-inducible promoter. With the conditional overexpression of either the wild type or a constitutively active version of Arabidopsis Galpha, transgenic seedlings exhibited a hypersensitive response to light. This enhanced light sensitivity was more exaggerated in a relatively lower intensity of light and was observed in white light as well as far-red, red, and blue light conditions. The enhanced responses in far-red and red light required functional phytochrome A and phytochrome B, respectively. Furthermore, the response to far-red light depended on functional FHY1 but not on FIN219 and FHY3. This dependence on FHY1 indicates that the Arabidopsis Galpha protein may act only on a discrete branch of the phytochrome A signaling pathway. Thus, our results support the involvement of a heterotrimeric G-protein in the light regulation of Arabidopsis seedling development.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, 165 Prospect Street, New Haven, CT 06520-8104, USA.
authors.forename: H
authors.initials: H
authors.lastname: Okamoto
authors.forename: M
authors.initials: M
authors.lastname: Matsui
authors.forename: X W
authors.initials: XW
authors.lastname: Deng
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins; D002454:Cell Differentiation; D002455:Cell Division; D044385:GTP-Binding Protein alpha Subunits; D018506:Gene Expression Regulation, Plant; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D018546:Hypocotyl / Q000254:growth & development* / Q000528:radiation effects; D008027:Light; D010641:Phenotype; D010834:Phytochrome / Q000502:physiology; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D018749:RNA, Plant; D011965:Receptors, Glucocorticoid / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction; D019076:Transgenes
chemical_list: D029681:Arabidopsis Proteins; C429765:GPA1 protein, Arabidopsis; D044385:GTP-Binding Protein alpha Subunits; D010940:Plant Proteins; D018749:RNA, Plant; D011965:Receptors, Glucocorticoid; D010834:Phytochrome; D020962:Heterotrimeric GTP-Binding Proteins