Hydrotropism interacts with gravitropism by degrading amyloplasts in seedling roots of Arabidopsis and radish

Nobuyuki Takahashi, Yutaka Yamazaki, Akie Kobayashi, Atsushi Higashitani, Hideyuki Takahashi

Research output: Contribution to journalArticlepeer-review

90 Citations (Scopus)

Abstract

In response to a moisture gradient, roots exhibit hydrotropism to control the orientation of their growth. To exhibit hydrotropism, however, they must overcome the gravitropism that is dominant on Earth. We found that moisture gradient or water stress caused immediate degradation of the starch anchors, amyloplasts, in root columella cells of Arabidopsis and radish (Raphanus sativus). Namely, development of hydrotropic response was accompanied by a simultaneous reduction in starch content in columella cells. Rapid degradation of amyloplasts in columella cells also occurred in the water-stressed roots with sorbitol or mannitol. Both hydrotropically stimulated and water-stressed roots showed a reduced responsiveness to gravity. Roots of a starchless mutant, pgm1-1, showed an enhanced hydrotropism compared with that of the wild type. These results suggest that the reduced responsiveness to gravity is, at least in part, attributable to the degradation of amyloplasts in columella cells. Thus, the reduction in gravitropism allows the roots to exhibit hydrotropism.

Original languageEnglish
Pages (from-to)805-810
Number of pages6
JournalPlant physiology
Volume132
Issue number2
DOIs
Publication statusPublished - 2003 Jun 1

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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