Journal Article

Hydrotropic Response and Expression Pattern of Auxin-Inducible Gene, <i> CS-IAA1</i>, in the Primary Roots of Clinorotated Cucumber Seedlings

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

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 7, pages 793-801
Published in print July 2002 | ISSN: 0032-0781
Published online July 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf093
Hydrotropic Response and Expression Pattern of Auxin-Inducible Gene,  CS-IAA1, in the Primary Roots of Clinorotated Cucumber Seedlings

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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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.

Keywords: Keywords: Auxin — Clinostat — CS-IAA1 — Cucumber (Cucumis sativus L.) — Hydrotropism — Roots.

Journal Article.  6219 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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