The type-A response regulator, ARR15, acts as a negative regulator in the cytokinin-mediated signal transduction in Arabidopsis thaliana

Takatoshi Kiba, Hisami Yamada, Shusei Sato, Tomohiko Kato, Satoshi Tabata, Takafumi Yamashino, Takeshi Mizuno

Research output: Contribution to journalArticlepeer-review

120 Citations (Scopus)

Abstract

The Arabidopsis thaliana AHK4 histidine kinase (also known as CRE1 or WOL) acts as a cytokinin signal transducer, presumably, in concert with downstream components, such as histidine-containing phosphotransfer factors (AHPs) and response regulators (ARRs), through the histidine-to-aspartate (His→Asp) phosphorelay. Among 10 members of the type-A ARR family, the cytokinin-induced expression of ARR15 in roots is selectively impaired in the cre1-1 mutant, which carries a mutation in the AHK4 gene, suggesting a link between this type-A response regulator and the AHK4-mediated cytokinin signal transduction in roots. To address this issue further, we characterized a T-DNA insertion mutant of ARR15, and also constructed transgenic lines (referred to as ARR15-ox) that overexpress the ARR15 gene in a manner independent of cytokinin. While the T-DNA insertion mutant (arr15-1) showed no apparent phenotype, the cytokinin-independent overexpression of ARR15 in ARR15-ox plants resulted in a reduced sensitivity toward exogenously applied cytokinin, not only in elongation of roots in plants, but also in green callus formation (or shoot formation) in explants. Cytokinin-induced expressions of certain type-A ARRs were also down-regulated in ARR15-ox plants. These results support the view that ARR15 acts as a repressor that mediates a negative feedback loop in the cytokinin and AHK4-mediated His→Asp phosphorelay.

Original languageEnglish
Pages (from-to)868-874
Number of pages7
JournalPlant and Cell Physiology
Volume44
Issue number8
DOIs
Publication statusPublished - 2003 Aug 1
Externally publishedYes

Keywords

  • Arabidopsis
  • Cytokinin
  • Histidine kinase
  • Phosphorelay
  • Response regulator
  • Signal transduction

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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