8-Epixanthatin, a light-induced growth inhibitor, mediates the phototropic curvature in sunflower (Helianthus annuus) hypocotyls

Kaori Yokotani-Tomita, Jun Kato, Kosumi Yamada, Seiji Kosemura, Shosuke Yamamura, Johan Bruinsma, Koji Hasegawa

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The distribution of the endogenous auxin-inhibiting substance, 8-epixanthatin, was determined in the lighted and shaded sides of phototropically-stimulated, de-etiolated sunflower (Helianthus annuus L. cv. Taiyo) hypocotyls. From 40 min after the onset of phototropic stimulation, the growth rate at the lighted side was inhibited, whereas that at the shaded side showed no change. In the lighted side, 8-epixanthatin increased by 20 min after the onset of unilateral illumination and, after 40 min, reached a 3-fold larger concentration than that in the shaded side. Unilateral application of 8-epixanthatin suppressed the growth of etiolated hypocotyls at the applied side only, causing the hypocotyls to bend at the site of application. It is concluded that phototropic curvature in sunflower hypocotyls is caused by a lateral gradient of the auxin-inhibiting substance 8-epixanthatin.

Original languageEnglish
Pages (from-to)326-330
Number of pages5
JournalPhysiologia Plantarum
Volume106
Issue number3
DOIs
Publication statusPublished - 1999 Jul 1

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science
  • Cell Biology

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