title: Phytochromes and cryptochromes regulate the differential growth of Arabidopsis hypocotyls in both a PGP19-dependent and a PGP19-independent manner.
abstract: Photoreceptors, phytochromes and cryptochromes regulate hypocotyl growth under specific conditions, by suppressing negative gravitropism, modulating phototropism and inhibiting elongation. Although these effects seem to be partially caused via the regulation of the phytohormone auxin, the molecular mechanisms underlying this process are still poorly understood. In our present study, we demonstrate that the flabby mutation enhances both phytochrome- and cryptochrome-inducible hypocotyl bending in Arabidopsis. The FLABBY gene encodes the ABC-type auxin transporter, PGP19, and its expression is suppressed by the activation of phytochromes and cryptochromes. Our current results therefore indicate that the phytochromes and cryptochromes have at least two effects upon the tropic responses of the hypocotyls in Arabidopsis: the enhancement of hypocotyl bending through the suppression of PGP19, and a PGP19-independent mechanism that induces hypocotyl bending. By the using an auxin polar transport assay and DR5:GUS expression analysis, we further find that the phytochromes inhibit basipetal auxin transport, and induce the asymmetric distribution of auxin in the hypocotyls. These data suggest that the control of auxin transport by phytochromes and cryptochromes is a critical regulatory component of hypocotyl growth in response to light.
authors: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230 0045, Japan.
authors: Akitomo
authors: A
authors: Nagashima
authors: Genki
authors: G
authors: Suzuki
authors: Yukiko
authors: Y
authors: Uehara
authors: Kensuke
authors: K
authors: Saji
authors: Toshiko
authors: T
authors: Furukawa
authors: Tomokazu
authors: T
authors: Koshiba
authors: Masayo
authors: M
authors: Sekimoto
authors: Shozo
authors: S
authors: Fujioka
authors: Takeshi
authors: T
authors: Kuroha
authors: Mikiko
authors: M
authors: Kojima
authors: Hitoshi
authors: H
authors: Sakakibara
authors: Noriko
authors: N
authors: Fujisawa
authors: Kiyotaka
authors: K
authors: Okada
authors: Tatsuya
authors: T
authors: Sakai
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001692:Biological Transport; D015152:Blotting, Northern; D015153:Blotting, Western; D056931:Cryptochromes; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism; D008027:Light; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D005420:Flavoproteins; D007210:Indoleacetic Acids; C519873:PGP19 protein, Arabidopsis; D010834:Phytochrome