title: From Zinnia to Arabidopsis: approaching the involvement of peroxidases in lignification.
abstract: Zinnia elegans constitutes one of the most useful model systems for studying xylem differentiation, which simultaneously involves secondary cell wall synthesis, cell wall lignification, and programmed cell death. Likewise, the in vitro culture system of Z. elegans has been the best characterized as the differentiation of mesophyll cells into tracheary elements allows study of the biochemistry and physiology of xylogenesis free from the complexity that heterogeneous plant tissues impose. Moreover, Z. elegans has emerged as an excellent plant model to study the involvement of peroxidases in cell wall lignification. This is due to the simplicity and duality of the lignification pattern shown by the stems and hypocotyls, and to the basic nature of the peroxidase isoenzyme. This protein is expressed not only in hypocotyls and stems but also in mesophyll cells transdifferentiating into tracheary elements. Therefore, not only does this peroxidase fulfil all the catalytic requirements to be involved in lignification overcoming all restrictions imposed by the polymerization step, but also its expression is inherent in lignification. In fact, its basic nature is not exceptional since basic peroxidases are differentially expressed during lignification in other model systems, showing unusual and unique biochemical properties such as oxidation of syringyl moieties. This review focuses on the experiments which led to a better understanding of the lignification process in Zinnia, starting with the basic knowledge about the lignin pattern in this plant, how lignification takes place, and how a sole basic peroxidase with unusual catalytic properties is involved and regulated by hormones, H2O2, and nitric oxide.
authors: Department of Plant Biology, University of Murcia, Murcia 30100, Spain. enovo@um.es
authors: Esther
authors: E
authors: Novo-Uzal
authors: Francisco
authors: F
authors: Fernández-Pérez
authors: Joaquín
authors: J
authors: Herrero
authors: Jorge
authors: J
authors: Gutiérrez
authors: Laura V
authors: LV
authors: Gómez-Ros
authors: María Ángeles
authors: MÁ
authors: Bernal
authors: José
authors: J
authors: Díaz
authors: Juan
authors: J
authors: Cuello
authors: Federico
authors: F
authors: Pomar
authors: María Ángeles
authors: MÁ
authors: Pedreño
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D019659:Asteraceae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D002454:Cell Differentiation; D002473:Cell Wall / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D010544:Peroxidases / Q000235:genetics* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism
chemical_list: D010937:Plant Growth Regulators; D009569:Nitric Oxide; D008031:Lignin; D006861:Hydrogen Peroxide; D010544:Peroxidases
keywords: Lignification; Zinnia elegans.; peroxidase; syringyl; tracheary element; xylem differentiation