NtZIP5A/B is involved in the regulation of Zn/Cu/Fe/Mn/Cd homeostasis in tobacco.

Plants grow in soils with varying concentrations of microelements, often in the presence of toxic metals e.g. Cd.

Regulation and Function of Metal Uptake Transporter NtNRAMP3 in Tobacco.

Natural resistance-associated macrophage protein () genes encode proteins with low substrate specificity, important for maintaining metal cross homeostasis in the cell. The role of these proteins in tobacco, an important crop plant with wide application in the tobacco industry as well as in phytoremediation of metal-contaminated soils, remains unknown. Here, we identified NtNRAMP3, the closest homologue to NRAMP3 proteins from other plant species, and functionally characterized it.

Suppression of / Changes Zn and Cd Root-to-Shoot Translocation in a Zn/Cd Status-Dependent Manner.

In tobacco, the efficiency of Zn translocation to shoots depends on Zn/Cd status. Previous studies pointed to the specific contribution of root parts in the regulation of this process, as well as the role of / (from the ZIP family; Zrt Irt-like Proteins). Here, to verify this hypothesis, / RNAi lines were generated.

Identification and characterization of a tobacco metal tolerance protein, .

Metal tolerance proteins (MTPs) from the CDF (Cation Diffusion Facilitator) family are efflux transporters that play a crucial role in metal homeostasis by maintaining optimal metal concentrations in the cytoplasm. Here, a novel tobacco NtMTP2 transporter was cloned and characterized. It encodes a 512 aa protein containing all specific CDF family domains.

Zn/Cd status-dependent accumulation of Zn and Cd in root parts in tobacco is accompanied by specific expression of ZIP genes.

Background: Root-to-shoot translocation of zinc (Zn) and cadmium (Cd) depends on the concentrations of both metals in the medium. A previous study on tobacco (Nicotiana tabacum) pointed to the contribution of NtZIP1, NtZIP2, NtZIP4 and NtIRT1-like in the regulation of this phenomenon. To learn more, Zn and Cd accumulation, root/shoot distribution and the expression of ZIP genes were investigated in the apical, middle and basal root parts.

Functional Analysis of and Zn Status-Dependent Expression Pattern of Tobacco Genes.

Tobacco is frequently considered as a plant useful for phytoremediation of metal-contaminated soil, despite the mechanisms for regulation of uptake and accumulation being largely unknown. Here we cloned and characterized a new tobacco Zn and Cd transporter from the ZIP family (ZRT-IRT-Like proteins). It complemented the Zn-uptake defective yeast mutant , and rendered the wild type DY1457 yeast more sensitive to Cd.

Contribution of NtZIP1-Like to the Regulation of Zn Homeostasis.

Tobacco has frequently been suggested as a candidate plant species for use in phytoremediation of metal contaminated soil but knowledge on the regulation of its metal-homeostasis is still in the infancy. To identify new tobacco metal transport genes that are involved in Zn homeostasis a bioinformatics study using the tobacco genome information together with expression analysis was performed. Ten new tobacco metal transport genes from the ZIP, NRAMP, MTP, and MRP/ABCC families were identified with expression levels in leaves that were modified by exposure to Zn excess.

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.

Engineering high Zn in tomato shoots through expression of AtHMA4 involves tissue-specific modification of endogenous genes.

Background: To increase the Zn level in shoots, AtHMA4 was ectopically expressed in tomato under the constitutive CaMV 35S promoter. However, the Zn concentration in the shoots of transgenic plants failed to increase at all tested Zn levels in the medium. Modification of Zn root/shoot distribution in tomato expressing 35S::AtHMA4 depended on the concentration of Zn in the medium, thus indicating involvement of unknown endogenous metal-homeostasis mechanisms.

Determination the Usefulness of Expression in Biofortification Strategies.

from encodes Zn/Cd export protein that controls Zn/Cd translocation to shoots. The focus of this manuscript is the evaluation of expression in tomato for mineral biofortification (more Zn and less Cd in shoots and fruits). Hydroponic and soil-based experiments were performed.

Approach to engineer tomato by expression of AtHMA4 to enhance Zn in the aerial parts.

The aim of this work was to assess the potential for using AtHMA4 to engineer enhanced efficiency of Zn translocation to shoots, and to increase the Zn concentration in aerial tissues of tomato. AtHMA4, a P1B-ATPase, encodes a Zn export protein known to be involved in the control of Zn root-to-shoot translocation. In this work, 35S::AtHMA4 was expressed in tomato (Lycopersicon esculentum var.

Phenotypic and molecular consequences of overexpression of metal-homeostasis genes.

Metal hyperaccumulating plants are able to store very large amounts of metals in their shoots. There are a number of reasons why it is important to be able to introduce metal hyperaccumulation traits into non-accumulating species (e.g.

HMA4 expression in tobacco reduces Cd accumulation due to the induction of the apoplastic barrier.

Ectopic expression in tobacco (Nicotiana tabacum v. Xanthi) of the export protein AtHMA4 (responsible in Arabidopsis for the control of Zn/Cd root to shoot translocation) resulted in decreased Cd uptake/accumulation in roots and shoots. This study contributes to understanding the mechanisms underlying this Cd-dependent phenotype to help predict the consequences of transgene expression for potential phytoremediation/biofortification-based strategies.

Expression of HvHMA2 in tobacco modifies Zn-Fe-Cd homeostasis.

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.

Development of Zn-related necrosis in tobacco is enhanced by expressing AtHMA4 and depends on the apoplastic Zn levels.

AtHMA4 was previously shown to contribute to the control of Zn root-to-shoot translocation and tolerance to high Zn. However, heterologous expression of 35S::AtHMA4 in tobacco (Nicotiana tabacum cv. Xanthi) results in enhanced Zn sensitivity.

Metal response of transgenic tomato plants expressing P(1B) -ATPase.

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.

Metal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply.

Engineering enhanced transport of zinc to the aerial parts of plants is a major goal in bio-fortification. In Arabidopsis halleri, high constitutive expression of the AhHMA4 gene encoding a metal pump of the P(1B)-ATPase family is necessary for both Zn hyperaccumulation and the full extent of Zn and Cd hypertolerance that are characteristic of this species. In this study, an AhHMA4 cDNA was introduced into N.

Transcriptional regulation of the gluB promoter during plant response to infection.

Several studies suggest that plant hydrolytic enzymes, such as 1,3-beta-glucanases, may be components of a general defense system against pathogen invasion in several different plant species. We isolated and characterized a genomic sequence coding for a new acidic 1,3-beta-glucanase (gluB) from Solanum tuberosum. The 5' flanking region of the gluB gene was also characterized.