title: Shoot Removal Induces Chloroplast Development in Roots via Cytokinin Signaling.
abstract: The development of plant chloroplasts is regulated by various developmental, environmental, and hormonal cues. In Arabidopsis (Arabidopsis thaliana), chloroplast development is repressed in roots via auxin signaling. However, roots develop chloroplasts when they are detached from the shoot. In contrast to auxin, cytokinin positively affects chloroplast development in roots, but the role and signaling pathway of cytokinin in the root greening response remain unclear. To understand the regulatory pathways of chloroplast development in the plant stress response, we examined the mechanisms underlying the conditional greening of detached roots. In wild-type Arabidopsis roots, shoot removal activates type B ARABIDOPSIS RESPONSE REGULATOR (ARR)-mediated cytokinin signaling and induces chlorophyll accumulation and photosynthetic remodeling. ARR1 and ARR12 are essential for up-regulating nucleus- and plastid-encoded genes associated with chloroplast development in detached roots. In this process, WOUND INDUCED DEDIFFERENTIATION1 and class B GATA transcription factors (B-GATAs) act upstream and downstream of ARRs, respectively. Overexpression of B-GATAs promotes root greening, as does shoot removal, dependent on a light signaling transcription factor, LONG HYPOCOTYL5. Auxin represses the root greening response independent of ARR signaling.GNC-LIKE(GNL), a B-GATA, is strongly up-regulated in detached roots via ARR1 and ARR12 but is repressed by auxin, soGNLmay function at the point of convergence of cytokinin and auxin signaling in the root greening response.
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and kkobayashi@bio.c.u-tokyo.ac.jp.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.) kkobayashi@bio.c.u-tokyo.ac.jp.
authors.forename: Koichi
authors.identifier: 0000-0003-3726-4790
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Ai
authors.identifier: 0000-0002-0766-3638
authors.initials: A
authors.lastname: Ohnishi
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Daichi
authors.initials: D
authors.lastname: Sasaki
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Sho
authors.initials: S
authors.lastname: Fujii
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Akira
authors.identifier: 0000-0003-3294-7939
authors.initials: A
authors.lastname: Iwase
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Keiko
authors.identifier: 0000-0002-9209-8230
authors.initials: K
authors.lastname: Sugimoto
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Department of Life Sciences (K.K., A.O., D.S., S.F., H.W.) and Department of General Systems Studies (T.M.), Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan; and.|RIKEN Center for Sustainable Resource Science, Tsurumi, Yokohama, Kanagawa 230-0045, Japan (A.I., K.S.).
authors.forename: Hajime
authors.identifier: 0000-0002-1585-5832
authors.initials: H
authors.lastname: Wada
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism* / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018519:Meristem / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009154:Mutation; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C117138:ARR1 protein, Arabidopsis; C519632:ARR12 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004268:DNA-Binding Proteins; D010937:Plant Growth Regulators; D014157:Transcription Factors; D002734:Chlorophyll