Phytochromes and cryptochromes regulate the differential growth of Arabidopsis hypocotyls in both a PGP19-dependent and a PGP19-independent manner

Akitomo Nagashima, Genki Suzuki, Yukiko Uehara, Kensuke Saji, Toshiko Furukawa, Tomokazu Koshiba, Masayo Sekimoto, Shozo Fujioka, Takeshi Kuroha, Mikiko Kojima, Hitoshi Sakakibara, Noriko Fujisawa, Kiyotaka Okada, Tatsuya Sakai

    Research output: Contribution to journalArticlepeer-review

    63 Citations (Scopus)

    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.

    Original languageEnglish
    Pages (from-to)516-529
    Number of pages14
    JournalPlant Journal
    Volume53
    Issue number3
    DOIs
    Publication statusPublished - 2008 Feb

    Keywords

    • Auxin transport
    • Cryptochrome
    • Hypocotyl growth
    • Light signaling
    • PGP19
    • Phytochrome

    ASJC Scopus subject areas

    • Genetics
    • Plant Science
    • Cell Biology

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