title: RPT2/NCH1 subfamily of NPH3-like proteins is essential for the chloroplast accumulation response in land plants.
abstract: In green plants, the blue light receptor kinase phototropin mediates various photomovements and developmental responses, such as phototropism, chloroplast photorelocation movements (accumulation and avoidance), stomatal opening, and leaf flattening, which facilitate photosynthesis. In Arabidopsis, two phototropins (phot1 and phot2) redundantly mediate these responses. Two phototropin-interacting proteins, NONPHOTOTROPIC HYPOCOTYL 3 (NPH3) and ROOT PHOTOTROPISM 2 (RPT2), which belong to the NPH3/RPT2-like (NRL) family of BTB (broad complex, tramtrack, and bric à brac) domain proteins, mediate phototropism and leaf flattening. However, the roles of NRL proteins in chloroplast photorelocation movement remain to be determined. Here, we show that another phototropin-interacting NRL protein, NRL PROTEIN FOR CHLOROPLAST MOVEMENT 1 (NCH1), and RPT2 redundantly mediate the chloroplast accumulation response but not the avoidance response. NPH3, RPT2, and NCH1 are not involved in the chloroplast avoidance response or stomatal opening. In the liverwort Marchantia polymorpha, the NCH1 ortholog, MpNCH1, is essential for the chloroplast accumulation response but not the avoidance response, indicating that the regulation of the phototropin-mediated chloroplast accumulation response by RPT2/NCH1 is conserved in land plants. Thus, the NRL protein combination could determine the specificity of diverse phototropin-mediated responses.
authors: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 819-0395, Japan; Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan suetsugu@lif.kyoto-u.ac.jp masamitsu.wada@gmail.com.
authors: Noriyuki
authors: 0000-0002-3328-3313
authors: N
authors: Suetsugu
authors: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 819-0395, Japan;
authors: Atsushi
authors: A
authors: Takemiya
authors: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 819-0395, Japan;
authors: Sam-Geun
authors: SG
authors: Kong
authors: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 819-0395, Japan;
authors: Takeshi
authors: T
authors: Higa
authors: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors: Aino
authors: A
authors: Komatsu
authors: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 819-0395, Japan;
authors: Ken-Ichiro
authors: K
authors: Shimazaki
authors: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors: Takayuki
authors: T
authors: Kohchi
authors: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 819-0395, Japan; suetsugu@lif.kyoto-u.ac.jp masamitsu.wada@gmail.com.
authors: Masamitsu
authors: M
authors: Wada
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics; D019669:Embryophyta / Q000254:growth & development / Q000378:metabolism; D008027:Light; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D018524:Phototropism / Q000235:genetics*; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development; D017346:Protein Serine-Threonine Kinases
chemical_list: D029681:Arabidopsis Proteins; C400222:NPH3 protein, Arabidopsis; C423903:PHOT2 protein, Arabidopsis; D010750:Phosphoproteins; C405209:RPT2 protein, Arabidopsis; C103646:NPH1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases
keywords: Arabidopsis; Marchantia; blue light; chloroplast movement; phototropin