Tissue-specific and DNA damage-responsive expression of the Arabidopsis RAD51 gene promoter in transgenic Arabidopsis and tobacco

Abstract

As is the case with other organisms, plants respond to genotoxic stresses by expressing DNA repair genes upon DNA damage. To uncover the mechanisms involved in regulated expression of the DNA damage-responsive gene, we investigated the tissue specific expression and DNA damage-responsiveness of the Arabidopsis RAD51 (AtRAD51) gene promoter in Arabidopsis and tobacco. Transgenic Arabidopsis and tobacco plants harboring AtRAD51 promoter- β-glucuronidase (GUS) were used to study the detailed expression pattern of the AtRAD51 gene. A histochemical GUS assay of bleomycin- or UV-treated plants showed that the AtRAD51 promoter in young tissues is actively expressed particularly in meristematic cells of the root and shoot apex of seedlings. In the absence of genotoxic stress, GUS activities were detected only at very low levels in these same organs. In mature plants, the AtRAD51 promoter is mainly expressed in flower bud, sepal, stigma, later anther, pedicel when treating with DNA damaging agent. The expression patterns of reporter assays were consistent with the AtRAD51 mRNA accumulation pattern. These results suggest that the regulated expression of the AtRAD51 gene is controlled mainly at the level of transcription directed primarily by the promoter function of the gene.