Cloning and functional analysis in transgenic tobacco of a tapetum-specific promoter from Arabidopsis
The 5’-flanking region of 1174 bp upstream of the translation start point (TSP) of a reported Arabidopsis anther-specific gene, Anther7 gene (ATA7), which putatively encodes a protein related to lipid transfer protein, was cloned and functionally analyzed in transgenic tobacco after been fused with β- glucuronidase (GUS) gene reporter. Histochemical GUS staining of the transgenic plants showed that the cloned fragment did drive GUS expression exclusively in the anther, not in any other parts of floral organs, including pollens and nor in any vegetative tissue. Transverse section of the GUS-blue anthers disclosed that the blue cells were present uniquely in the tapetum of the anther. A series of 5’-deletion of cloned fragment indicated that a short segment of 179 bp upstream of the TSP (-155 bp upstream of the transcription start site) retained not only the promoter’s driving power, but also its tapetum-specificity. Cis-acting element search in this short segment revealed the presence of numbers of organ- and tissuespecific motifs, including pollen-specific LAT52 and SLG13. These results indicated that the tapetumspecificity of ATA7 gene is mainly conferred by its promoter, and such a promoter, in particular, the core one should be useful both for identification of tapetum-involved genes and for biotechnological applications.
Key words: Arabidopsis, Anther7 gene of Arabidopsis theliana (ATA7), anther-specific promoter, tapetumspecific promoter.