A cis-element containing PAL-box functions in the expression of the wound-inducible peroxidase gene of horseradish.

In an attempt to understand the molecular basis of plant responses to wounding, we have investigated the transcriptional regulation of the wound-inducible prxC2 gene, which encodes horseradish peroxidase. In the previous work, 5'-deletion analysis revealed that a cis-element involved in the expression of the prxC2 gene is located at a position between -296 and -283 bp from the translation start site and contains a G-box sequence. We have also reported that a trans-acting factor, TFHP-1, can bind to the G-box sequence in this cis-element. Although the antisense RNA of TFHP-1 suppressed the expression of a prxC2 promoter-GUS chimeric gene in tobacco protoplasts, the sense RNA of TFHP-1 could not enhance this expression. These results suggested that other elements function in the expression of the prxC2 gene, and therefore additional deletion analysis of the promoter was performed with a transient expression system in cultured tobacco cells. Consequently, the second cis-element was found at a position between -177 and -134 bp from the translation start site of prxC2. This second cis-element contains a sequence similar to a PAL-box, and a nuclear protein possibly binds to it through the PAL-box sequence.