title: Expression of HvHMA2 in tobacco modifies Zn-Fe-Cd homeostasis.
abstract: HvHMA2 is a plasma membrane P1B-ATPase from barley that functions in Zn/Cd root-to-shoot transport. To assess the usefulness of HvHMA2 for modifying the metal content in aerial plant parts, it was expressed in tobacco under the CaMV35S promoter. Transformation with HvHMA2 did not produce one unique pattern of Zn and Cd accumulation; instead it depended on external metal supply. Thus Zn and Cd root-to-shoot translocation was facilitated, but not at all applied Zn/Cd concentrations. Metal uptake was restricted in HvHMA2-transformed plants and the level in the shoot was not enhanced. It was shown that HvHMA2 localizes to the plasma membrane of tobacco cells, and overloads the apoplast with Zn, which could explain the overall decrease in metal uptake observed. Despite the lower levels in the shoot, HvHMA2 transformants showed increased Zn sensitivity. Moreover, introduction of HvHMA2 into tobacco interfered with Fe metabolism and Fe accumulation was modified in HvHMA2-transformants in a Zn- and Cd-concentration dependent manner. The results indicate that ectopic expression of the export protein HvHMA2 in tobacco interferes with tobacco metal Zn-Cd-Fe cross-homeostasis, inducing internal mechanisms regulating metal uptake and tolerance.
authors.affiliation: Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Miecznikowa Street 1, 02-096 Warszawa, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Barabasz
authors.forename: Anna
authors.initials: A
authors.lastname: Wilkowska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Tracz
authors.forename: Anna
authors.initials: A
authors.lastname: Ruszczyńska
authors.forename: Ewa
authors.initials: E
authors.lastname: Bulska
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Mills
authors.forename: Lorraine E
authors.initials: LE
authors.lastname: Williams
authors.forename: Danuta Maria
authors.initials: DM
authors.lastname: Antosiewicz
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000502:physiology*; D060054:Agrobacterium / Q000235:genetics; D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D001467:Hordeum / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D002104:Cadmium; D000251:Adenosine Triphosphatases; D015032:Zinc
keywords: Cadmium; Heavy metal; HvHMA2; P(1B)-ATPase; Phytoremediation