title: Hormonal regulation of the basic peroxidase isoenzyme from Zinnia elegans.
abstract: Xylem differentiation in plants is under strict hormonal regulation. Auxins and cytokinins, together with brassinosteroids (BRs), appear to be the main hormones controlling vascular differentiation. In this report, we study the effect of these hormones on the basic peroxidase isoenzyme from Zinnia elegans (ZePrx), an enzyme involved in lignin biosynthesis. Results showed that auxins and cytokinins induce ZePrx, similarly to the way in which they induce seedling secondary growth (in particular, metaxylem differentiation). Likewise, the exogenous application of BR reduces the levels of ZePrx, in a similar way to their capacity to inhibit seedling secondary growth. Consistent with this notion, the exogenous application of BR reverses the auxin/cytokinin-induced ZePrx expression, but has no effect on the auxin/cytokinin-induced secondary growth. This differential hormonal response is supported by the analysis of the ZePrx promoter, which contains (a) cis-elements directly responsive to these hormones and (b) cis-elements targets of the plethora of transcription factors, such as NAC, MYB, AP2, MADS and class III HD Zip, which are up-regulated during the auxin- and cytokinin-induced secondary growth. Taken together, these results suggest that ZePrx is directly and indirectly regulated by the plethora of hormones that control xylem differentiation, supporting the role of ZePrx in xylem lignification.
authors.affiliation: Department of Plant Biology, University of La Coruña, 15071 La Coruña, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Gutiérrez
authors.forename: María Josefa
authors.initials: MJ
authors.lastname: López Núñez-Flores
authors.forename: Laura V
authors.initials: LV
authors.lastname: Gómez-Ros
authors.forename: Esther
authors.initials: E
authors.lastname: Novo Uzal
authors.forename: Alberto
authors.initials: A
authors.lastname: Esteban Carrasco
authors.forename: José
authors.initials: J
authors.lastname: Díaz
authors.forename: Mariana
authors.initials: M
authors.lastname: Sottomayor
authors.forename: Juan
authors.initials: J
authors.lastname: Cuello
authors.forename: Alfonso
authors.initials: A
authors.lastname: Ros Barceló
mesh_terms: D019659:Asteraceae / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development; D001483:Base Sequence; D001593:Benzyl Compounds; D060406:Brassinosteroids; D002777:Cholestanols / Q000494:pharmacology; D019295:Computational Biology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007701:Kinetin / Q000494:pharmacology; D008954:Models, Biological; D008969:Molecular Sequence Data; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011687:Purines; D036226:Seedlings / Q000166:cytology / Q000201:enzymology; D013260:Steroids, Heterocyclic / Q000494:pharmacology
chemical_list: D001593:Benzyl Compounds; D060406:Brassinosteroids; D002777:Cholestanols; D007527:Isoenzymes; D009280:Naphthaleneacetic Acids; D010937:Plant Growth Regulators; D011687:Purines; D013260:Steroids, Heterocyclic; C034182:1-naphthaleneacetic acid; D010544:Peroxidases; C480551:benzylaminopurine; D007701:Kinetin; C023623:brassinolide