title: Phototropin from Chlamydomonas reinhardtii is functional in Arabidopsis thaliana.
abstract: Phototropin, a plant blue light photoreceptor, mediates important blue light responses such as phototropism, chloroplast positioning and stomatal opening in higher plants. In Arabidopsis thaliana, two phototoropins, phototropin 1 and 2, are known. Recently, in the unicellular green alga, Chlamydomonas reinhardtii, a phototropin homolog was identified. It exhibits photochemical properties similar to those of higher plant phototropins and is involved in multiple steps of the sexual life cycle of Chlamydomonas. Here, we expressed Chlamydomonas phototropin in Arabidopsis to examine whether it is active in a distantly related plant species. The Arabidopsis mutant deficient in both phototropin 1 and 2 was transformed with a vector containing Chlamydomonas phototropin cDNA fused to a cauliflower mosaic virus 35S promoter. The resulting lines were classified into high, medium and low expressers based on RNA gel blot and immunoblot analyses. Typical phototropin responses were restored in high expression lines. These results demonstrate that Chlamydomonas phototropin is functional in higher plants. Hence, the basic mechanism of phototropin action is highly conserved, even though its apparent physiological functions are quite diverse.
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo-Ku, Kyoto, 606-8502 Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Onodera
authors.forename: Sam-Geun
authors.initials: SG
authors.lastname: Kong
authors.forename: Michio
authors.initials: M
authors.lastname: Doi
authors.forename: Ken-Ichiro
authors.initials: K
authors.lastname: Shimazaki
authors.forename: John
authors.initials: J
authors.lastname: Christie
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Mochizuki
authors.forename: Akira
authors.initials: A
authors.lastname: Nagatani
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins; D016825:Chlamydomonas reinhardtii / Q000235:genetics*; D002736:Chloroplasts / Q000502:physiology; D056931:Cryptochromes; D005420:Flavoproteins / Q000235:genetics* / Q000378:metabolism*; D007246:Infertility; D008027:Light; D010641:Phenotype; D018524:Phototropism / Q000235:genetics*; D018515:Plant Leaves / Q000502:physiology; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D005420:Flavoproteins