Identification of Cationic Cell-wall-bound Peroxidase Responsible for the Dehydrogenative Polymerization of Lignin in Poplus alba.L

Abstract

Previously, we reported that a peroxidase isoenzyme (cationic cell-wall-bound peroxidase, CWPO-C) from poplar callus preferentially oxidizes sinapyl alcohol and sinapyl alcohol polymer as substrates. In this study, CWPO-C cDNA sequence was cloned by the PCR technique, RT-PCR and RACE. Competitive PCR analysis showed that CWPO-C gene was expressed in lignified organs. However, wound stress did not induce CWPO-C gene transcription. These results showed that CWPO-C gene constantly expresses in lignified organs. Western analysis using polyclonal antiserum against CWPO-C showed that this antiserum recognized CWPO-C protein and that this peroxidase ionically bound to the cell walls of developing xylem. Immunohistochemical analysis showed that this peroxidase mainly located fiber cells in lignifying tissue. We will discuss this peroxidase isoenzyme as a lignification-specific peroxidase isoenzyme in woody angiosperms.