The ratio of Zn to Cd supply as a determinant of metal-homeostasis gene expression in tobacco and its modulation by overexpressing the metal exporter AtHMA4.
This study links changes in the tobacco endogenous metal-homeostasis network caused by transgene expression with engineering of novel features. It also provides insight into the concentration-dependent mutual interactions between Zn and Cd, leading to differences in the metal partitioning between wild-type and transgenic plants. In tobacco, expression of the export protein AtHMA4 modified Zn/Cd root/shoot distribution, but the pattern depended on their concentrations in the medium. To address this phenomenon, the expression of genes identified by suppression subtractive hybridization and the Zn/Cd accumulation pattern were examined upon exposure to six variants of low/high Zn and Cd concentrations. Five tobacco metal-homeostasis genes were identified: NtZIP2, NtZIP4, NtIRT1-like, NtNAS, and NtVTL. In the wild type, their expression depended on combinations of low/high Zn and Cd concentrations; co-ordinated responses of NtZIP1, NtZIP2, and NtVTL were shown in medium containing 4 µM Cd, and at 0.5 µM versus 10 µM Zn. In transgenics, qualitative changes detected for NtZIP1, NtZIP4, NtIRT1-like, and NtVTL are considered crucial for modification of Zn/Cd supply-dependent Zn/Cd root/shoot distribution. Notwithstanding, NtVTL was the most responsive gene in wild-type and transgenic plants under all concentrations of Zn and Cd tested; thus it is a candidate gene for the regulation of metal cross-homeostasis processes involved in engineering new metal-related traits.
University of Warsaw, Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, Department of Plant Anatomy and Cytology, Miecznikowa str 1, 02-096 Warszawa, Poland.
Anna
A
Barabasz
University of Warsaw, Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, Department of Plant Anatomy and Cytology, Miecznikowa str 1, 02-096 Warszawa, Poland.
Maria
M
Klimecka
University of Warsaw, Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, Department of Plant Anatomy and Cytology, Miecznikowa str 1, 02-096 Warszawa, Poland.
Maria
M
Kendziorek
University of Warsaw, Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, Department of Plant Anatomy and Cytology, Miecznikowa str 1, 02-096 Warszawa, Poland.
Aleksandra
A
Weremczuk
University of Warsaw, Faculty of Chemistry, Pasteura str. 1, 02-093 Warszawa, Poland.
Anna
A
Ruszczyńska
University of Warsaw, Faculty of Chemistry, Pasteura str. 1, 02-093 Warszawa, Poland.
Ewa
E
Bulska
University of Warsaw, Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, Department of Plant Anatomy and Cytology, Miecznikowa str 1, 02-096 Warszawa, Poland dma@biol.uw.edu.pl.
Danuta Maria
DM
Antosiewicz
D000251:Adenosine Triphosphatases / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology*; D002104:Cadmium / Q000494:pharmacology*; D027682:Cation Transport Proteins / Q000502:physiology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D006706:Homeostasis / Q000187:drug effects*; D010940:Plant Proteins / Q000502:physiology; D030821:Plants, Genetically Modified; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D066251:Subtractive Hybridization Techniques; D014026:Nicotiana / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology*
D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D010940:Plant Proteins; D002104:Cadmium; D000251:Adenosine Triphosphatases; C477864:HMA4 protein, Arabidopsis; D015032:Zinc
AtHMA4; SSH; cadmium; tobacco; transformation; zinc.