Hydrotropic response and expression pattern of auxin-inducible gene, CS-IAA1, in the primary roots of clinorotated cucumber seedlings

Hidetoshi Mizuno, Akie Kobayashi, Nobuharu Fujii, Masamichi Yamashita, Hideyuki Takahashi

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

Primary roots of cucumber seedlings showed positive hydrotropism when exposed to a moisture gradient and rotated on a two-axis clinostat. To examine the role of auxin in the differential growth of the hydrotropically responding roots, we first examined the expression of auxin-inducible genes, CS-AUX/IAAs, in cucumber roots. After auxin starvation, mRNA levels of CS-IAA1 and CS-IAA3 decreased in the roots. Applying auxin to the auxin-starved roots resulted in accumulation of CS-IAA1 and CS-IAA3 mRNA. The level of expression of these genes increased when the auxin concentration was increased. CS-IAA1 mRNA accumulated in response to 10-8 M auxin, and the level increased further, depending on the dose. Auxin starvation did not result in a decrease in the level of CS-IAA2 mRNA; however, adding exogenous auxin at concentrations higher than 10-7 M increased its accumulation. In the primary roots responding hydrotropically or gravitropically, CS-IAA1 expression was greater on the concave side of the curving roots than on the convex side. The difference could be detected 30 min following stimulation by gravity or a moisture gradient, and that difference increased with time. These results support the idea that asymmetry of localization of auxin is associated with differential growth in hydrotropically responding roots.

Original languageEnglish
Pages (from-to)793-801
Number of pages9
JournalPlant and Cell Physiology
Volume43
Issue number7
DOIs
Publication statusPublished - 2002

Keywords

  • Auxin
  • CS-IAA1
  • Clinostat
  • Cucumber (Cucumis sativus L.)
  • Hydrotropism
  • Roots

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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