The Populus alba cationic cell-wall-bound peroxidase (CWPO-C) regulates plant growth, lignin content and composition in poplar

Abstract Cationic cell-wall-bound peroxidase (CWPO-C) from Populus alba is the only Class III that has been shown to be able oxidize high molecular weight lignin polymers sinapyl alcohol and previously, believed a polymerization-specific peroxidase. However, using an Arabidopsis heterologous expression system, we showed recently CWPO-C contributes differentiation or early growth involved in auxin catabolism. In this study, clarify function of poplar, analyzed gene phenotypic changes with overexpression suppression. Real-time PCR monitoring promoter activity β-glucuronidase (GUS) assay revealed was strongly expressed immature tissues, such as upper stem, axillary buds, young leaves, addition developing xylem. transgenic poplars which upregulated suppressed, stem growth, gravitropism bending time, content syringyl/guaiacyl (S/G) composition were observed. Overexpressing enhanced gravitropic response (shorter time). With suppressed expression, reduced approximately 45% S/G ratio decreased by half. These results suggest plays role well polymerization.