Cloning of a Ca(2+)-ATPase gene and the role of cytosolic Ca2+ in the gibberellin-dependent signaling pathway in aleurone cells

Plant J. 1997 Mar;11(3):363-71. doi: 10.1046/j.1365-313x.1997.11030363.x.

Abstract

The ultimate goal of this investigation was to identify intermediary steps in the gibberellin (GA)-dependent signaling pathway in rice aleurone cells. By using a differential display approach, a number of putative GA-responsive genes were isolated. One of them, a GA-responsive Ca(2+)-ATPase gene, was identified and partially characterized. A genomic clone and a cDNA clone were isolated and sequenced. The deduced amino acid sequence showed that this protein resembles an endoplasmic reticulum membrane Ca(2+)-ATPase. In a transient assay in rice aleurone cells, expression of the introduced Ca(2+)-ATPase cDNA bypassed the GA requirement for stimulating the expression of a major target gene, the alpha-amylase c gene (Osamy-c). This result suggests that GA-dependent expression of this Ca(2+)-ATPase gene (OsCa-atpase) plays an important role in the GA-dependent signal-transduction pathway. To investigate the possible involvement of other proteins and genes that may affect the intracellular Ca2+ level, compounds which can block different putative steps in the signal-transduction pathway were introduced into rice aleurone cells, and then the level of the OsCa-atpase transcript or the Osamy-c transcript was monitored. In the presence of GA, the rice Ca(2+)-ATPase and the Ca2+ channels appeared to co-regulate the local concentration of cytosolic Ca2+. The release of Ca2+ from the internal stores to the cytoplasm was presumably initiated by inositol-1,4,5-triphosphate which reached a peak level within 25 min after GA induction. As a second messenger, Ca2+ binds to calmodulin (CaM), and the Ca2+/CaM complex regulates the cytosolic Ca2+ by affecting expression of the OsCa-atpase. Finally, a working model is proposed for the GA-dependent signaling pathway in aleurone cells.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium / metabolism*
  • Calcium-Transporting ATPases / biosynthesis*
  • Calcium-Transporting ATPases / chemistry
  • Calcium-Transporting ATPases / genetics
  • Cloning, Molecular
  • Cytosol / metabolism
  • DNA, Complementary
  • Endoplasmic Reticulum / enzymology
  • Genes, Reporter
  • Gibberellins / metabolism*
  • Luciferases / biosynthesis
  • Lycopersicon esculentum / enzymology
  • Molecular Sequence Data
  • Oryza / enzymology
  • Oryza / physiology*
  • Rabbits
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / chemistry
  • Sequence Homology, Amino Acid
  • Signal Transduction*
  • Transcription, Genetic
  • alpha-Amylases / biosynthesis
  • alpha-Amylases / genetics

Substances

  • DNA, Complementary
  • Gibberellins
  • Recombinant Fusion Proteins
  • Luciferases
  • alpha-Amylases
  • Calcium-Transporting ATPases
  • Calcium

Associated data

  • GENBANK/U82966