Abstract
In higher plants, APX isoenzymes play a key role in scavenging H2O2 and are distributed in at least five distinct cell compartments. Recently, we studied the effects of several stress conditions on the expression of spinach APX isoenzymes. The transcript level of cytosolic APX (cAPX) increased in response to photooxidative stresses, while the levels of other APX isoenzymes were not changed. These results suggest that cAPX may function to control strictly the cytosolic level of H2O2 under normal and stress conditions. To clarify the cAPX promoter region for potential binding site of regulatory transcription factors, we constructed chimeric genes consisting of a series of deletion of the cAPX promoter 5' region and GUS gene, and generated the transgenic Arabidopsis plants. The sequence element between -1325 and -860 of cAPX promoter seems to be essential for the high light-induced expression of the GUS gene.
