Abstract
A unique Ca2+-binding protein found in radish (RVCaB) is an acidic protein without aromatic amino acid or cysteine. We found five orthologues of RVCaB in A. thaliana (AtCaB1 to AtCaB5). Three of AtCaBs (AtCaB1, 2, and 3) have a relatively high similarity. These three proteins linked with GFP were localized to the cytosol in transiently expressed cells. Then we determined their mRNA levels in Arabidopis plants, which were treated with metal ions or phytohormones, by the real-time PCR method. AtCaB1 was constitutively expressed in leaves and stems, and AtCaB2 and AtCaB3 were expressed in roots. Interestingly, the mRNA levels of AtCaB1 and AtCaB2 were increased to 10-fold under the dark conditions. Furthermore, the mRNA levels of three AtCaBs were markedly increased after treatment with gibberellic acid. We will report our observations on the effects of metal ions and other phytohormones and phenotypic characteristics of their over-expressed mutant lines.
