A novel regulatory pathway of sulfate uptake in Arabidopsis roots: implication of CRE1/WOL/AHK4-mediated cytokinin-dependent regulation

Plant J. 2004 Jun;38(5):779-89. doi: 10.1111/j.1365-313X.2004.02079.x.

Abstract

Cytokinin is an adenine derivative plant hormone that generally regulates plant cell division and differentiation in conjunction with auxin. We report that a major cue for the negative regulation of sulfur acquisition is executed by cytokinin response 1 (CRE1)/wooden leg (WOL)/Arabidopsis histidine kinase 4 (AHK4) cytokinin receptor in Arabidopsis root. We constructed a green fluorescent protein (GFP) reporter system that generally displays the expression of the high-affinity sulfate transporter SULTR1;2 in Arabidopsis roots. GFP under the control of SULTR1;2 promoter showed typical sulfur responses that correlate with the changes in SULTR1;2 mRNA levels; accumulation of GFP was induced by sulfur limitation (-S), but was repressed in the presence of reduced sulfur compounds. Among the plant hormones tested, cytokinin significantly downregulated the expression of SULTR1;2. SULTR1;1 conducting sulfate uptake in sultr1;2 mutant was similarly downregulated by cytokinin. Downregulation of SULTR1;1 and SULTR1;2 by cytokinin correlated with the decrease in sulfate uptake activities in roots. The effect of cytokinin on sulfate uptake was moderated in the cre1-1 mutant, providing genetic evidence for involvement of CRE1/WOL/AHK4 in the negative regulation of high-affinity sulfate transporters. These data demonstrated the physiological importance of the cytokinin-dependent regulatory pathway in acquisition of sulfate in roots. Our results suggested that two different modes of regulation, represented as the -S induction and the cytokinin-dependent repression of sulfate transporters, independently control the uptake of sulfate in Arabidopsis roots.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Biological Transport
  • Cytokinins / physiology*
  • DNA Primers
  • Gene Expression Regulation, Plant
  • Green Fluorescent Proteins
  • Histidine Kinase
  • Indoleacetic Acids / metabolism
  • Luminescent Proteins / genetics
  • Plant Growth Regulators / metabolism
  • Plant Roots / metabolism*
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / metabolism
  • Protein Kinases / genetics*
  • Protein Kinases / metabolism*
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / physiology
  • Sulfates / metabolism*

Substances

  • Arabidopsis Proteins
  • Cytokinins
  • DNA Primers
  • Indoleacetic Acids
  • Luminescent Proteins
  • Plant Growth Regulators
  • Receptors, Cell Surface
  • Sulfates
  • Green Fluorescent Proteins
  • Protein Kinases
  • Histidine Kinase
  • WOL protein, Arabidopsis