title: Metal response of transgenic tomato plants expressing P(1B) -ATPase.
abstract: Heterologous expression of HMA4 (P(1B) -ATPase) in plants is a useful strategy to engineer altered metal distribution in tissues for biofortification or phytoremediation purposes. This study contributes to understanding mechanisms underlying complex Zn-dependent phenotypes observed in transgenic plants and to better predict the consequences of transgene expression. Tomato was transformed with AhHMA4(p1) ::AhHMA4 from Arabidopsis halleri encoding the Zn export protein involved in xylem loading of Zn. Homozygous lines were tested for Zn tolerance, Zn and Fe concentrations in organs and in the apoplastic fluid, and for the expression of the transgene and tomato metal homeostasis endogenes. Expression of AhHMA4 facilitates root-to-shoot Zn translocation and induces Zn uptake in a Zn supply-dependent manner. Unexpectedly, it increases Zn excess-triggered Fe deficiency in leaves and transcriptional activation of Fe-uptake systems in roots. Moreover, AhHMA4 expression causes Zn overload of the apoplast, which may contribute to enhanced Zn sensitivity of transgenics and may lead to cell-wall remodeling. This study highlights that alteration of the apoplast/symplast Zn status through introduction of cellular Zn export activity via AhHMA4 may alter tomato metal homeostasis network, thus seems to be crucial in the generation of the phenotype of transgenic tomato.
authors.affiliation: Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa 1, PL-02-096 Warszawa, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Barabasz
authors.forename: Anna
authors.initials: A
authors.lastname: Wilkowska
authors.forename: Anna
authors.initials: A
authors.lastname: Ruszczyńska
authors.forename: Ewa
authors.initials: E
authors.lastname: Bulska
authors.forename: Marc
authors.initials: M
authors.lastname: Hanikenne
authors.forename: Magdalena
authors.initials: M
authors.lastname: Czarny
authors.forename: Ute
authors.initials: U
authors.lastname: Krämer
authors.forename: Danuta Maria
authors.initials: DM
authors.lastname: Antosiewicz
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000378:metabolism*; D019076:Transgenes; D015032:Zinc / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D000251:Adenosine Triphosphatases; D015032:Zinc