title: Wound healing response and xylem differentiation in tobacco plants over-expressing a fungal endopolygalacturonase is mediated by copper amine oxidase activity.
abstract: In this work, we have investigated the involvement of copper amine oxidase (CuAO; EC 1.4.3.21) in wound healing and xylem differentiation of Nicotiana tabacum plants over-expressing a fungal endopolygalacturonase (PG plants), which show constitutively activated defence responses. In petioles and stems of PG plants, we found higher CuAO activity and lower polyamine (PA) levels, particularly putrescine (Put), with respect to wild-type (WT) plants. Upon wounding, a more intense autofluorescence of cell wall phenolics was observed in correspondence of wound surface, extending to epidermis and cortical parenchima only in PG plants. This response was mostly dependent on CuAO activity, as suggested by the reversion of autofluorescence upon supply of 2-bromoethylamine (2-BrEt), a CuAO specific inhibitor. Moreover, in unwounded plants, histochemical analysis revealed a tissue-specific expression of the enzyme in the vascular cambium and neighboring derivative cells of both petioles and stems of PG plants, whereas the corresponding WT tissues appeared unstained or faintly stained. A higher histochemical CuAO activity was also observed in xylem cells of PG plants as compared to WT xylem tissues suggesting a peculiar role of CuAO activity in xylem differentiation in PG plants. Indeed, roots of PG plants exhibited early xylem differentiation, a phenotype consistent with both the higher CuAO and the lower Put levels observed and supported by the 2-BrEt-mediated reversion of early root xylem differentiation and H2O2 accumulation. These results strongly support the relevance of PA-catabolism derived H2O2 in defence responses, such as those signaled by a compromised status of cell wall pectin integrity.
authors.affiliation: Dipartimento di Scienze, Università degli Studi "Roma Tre", V.le G. Marconi 446, 00146 Roma, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cona
authors.affiliation: Dipartimento di Scienze, Università degli Studi "Roma Tre", V.le G. Marconi 446, 00146 Roma, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Tisi
authors.affiliation: Dipartimento di Scienze, Università degli Studi "Roma Tre", V.le G. Marconi 446, 00146 Roma, Italy.
authors.forename: Sandip Annasaheb
authors.initials: SA
authors.lastname: Ghuge
authors.affiliation: Dipartimento di Scienze, Università degli Studi "Roma Tre", V.le G. Marconi 446, 00146 Roma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Franchi
authors.affiliation: Dipartimento di Biologia e Biotecnologie Charles Darwin, Sapienza Università di Roma, 00185 Roma, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: De Lorenzo
authors.affiliation: Dipartimento di Scienze, Università degli Studi "Roma Tre", V.le G. Marconi 446, 00146 Roma, Italy. Electronic address: riccardo.angelini@uniroma3.it.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Angelini
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D011096:Polygalacturonase / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014945:Wound Healing / Q000235:genetics / Q000502:physiology; D052584:Xylem / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D006631:Amine Oxidase (Copper-Containing); D011096:Polygalacturonase
keywords: Copper-containing amine oxidases; Polyamines; Polygalacturonases; Wound-healing; Xylem differentiation