title: Gravistimulation changes the accumulation pattern of the CsPIN1 auxin efflux facilitator in the endodermis of the transition zone in cucumber seedlings.
abstract: Cucumber (Cucumis sativus) seedlings grown in a horizontal position develop a specialized protuberance (or peg) on the lower side of the transition zone between the hypocotyl and the root. This occurs by suppressing peg formation on the upper side via a decrease in auxin resulting from a gravitational response. However, the gravity-stimulated mechanism of inducing asymmetric auxin distribution in the transition zone is poorly understood. The gravity-sensing tissue responsible for regulating auxin distribution in the transition zone is thought to be the endodermal cell. To characterize the gravity-stimulated mechanism, the auxin efflux facilitator PIN-FORMED1 (CsPIN1) in the endodermis was identified and the localization of CsPIN1 proteins during the gravimorphogenesis of cucumber seedlings was examined. Immunohistochemical analysis revealed that the accumulation pattern of CsPIN1 protein in the endodermal cells of the transition zone of cucumber seedlings grown horizontally differed from that of plants grown vertically. Gravistimulation for 30 min prompted changes in the accumulation pattern of CsPIN1 protein in the endodermis as well as the asymmetric distribution of auxin in the transition zone. Furthermore, 2,3,5-triiodobenzoic acid inhibited the differential distribution of auxin as well as changes in the accumulation pattern of CsPIN1 in the endodermis of the transition zone during gravistimulation. These results suggest that the altered pattern of CsPIN1 accumulation in the endodermis in response to gravistimulation influences lateral auxin transport through the endodermis, resulting in asymmetric auxin distribution in the transition zone.
authors: Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan.
authors: Chiaki
authors: C
authors: Watanabe
authors: Nobuharu
authors: N
authors: Fujii
authors: Kenichi
authors: K
authors: Yanai
authors: Takuya
authors: T
authors: Hotta
authors: Dai-Hee
authors: DH
authors: Kim
authors: Motoshi
authors: M
authors: Kamada
authors: Yuko
authors: Y
authors: Sasagawa-Saito
authors: Takeshi
authors: T
authors: Nishimura
authors: Tomokazu
authors: T
authors: Koshiba
authors: Yutaka
authors: Y
authors: Miyazawa
authors: Kyung-Min
authors: KM
authors: Kim
authors: Hideyuki
authors: H
authors: Takahashi
mesh_terms: D018553:Cucumis sativus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D006112:Gravitation; D007210:Indoleacetic Acids / Q000378:metabolism*; D009928:Organ Specificity; D010802:Phylogeny; D019441:Plant Epidermis / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism*; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D007210:Indoleacetic Acids; D010940:Plant Proteins; D012333:RNA, Messenger; D014283:Triiodobenzoic Acids; C052968:2,3,5-triiodobenzoic acid