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Glutathione (GSH) is a vital compound involved in several plant metabolic pathways. Our previous study indicated that foliar GSH application can increase zinc (Zn) levels in leafy vegetables. The objective of this study was to determine the mode of action of GSH as it relates to Zn transport from roots to shoots. Two types of transgenic Arabidopsis plants with genes for GSH synthesis, including StGCS-GS or AtGSH1 driven by the leaf-specific promoter of chlorophyll a/b-binding protein (pCab3) gene were generated. Both types of transgenic Arabidopsis plants showed significant increases in shoot GSH concentrations compared to the wild type (WT). Monitoring 65Zn movement by positron-emitting tracer imaging system (PETIS) analysis indicated that the 65Zn amount in the shoots of both types of transgenic Arabidopsis plants were higher than that in the WT. GSH concentration in phloem sap was increased significantly in WT with foliar applications of 10 mM GSH (WT-GSH), but not in transgenic Arabidopsis with elevated foliar GSH synthesis. Both types of transgenic Arabidopsis with elevated foliar GSH synthesis and WT-GSH exhibited increased shoot Zn concentrations and Zn translocation ratios. These results suggest that enhancement of endogenous foliar GSH synthesis and exogenous foliar GSH application affect root-to-shoot transport of Zn.

Glutathione (GSH) is a vital compound involved in several plant metabolic pathways. Our previous study indicated that foliar GSH application can increase zinc (Zn) levels in leafy vegetables. The objective of this study was to determine the mode of action of GSH as it relates to Zn transport from roots to shoots. Two types of transgenic Arabidopsis plants with genes for GSH synthesis, including StGCS-GS or AtGSH1 driven by the leaf-specific promoter of chlorophyll a/b-binding protein (pCab3) gene were generated. Both types of transgenic Arabidopsis plants showed significant increases in shoot GSH concentrations compared to the wild type (WT). Monitoring 65Zn movement by positron-emitting tracer imaging system (PETIS) analysis indicated that the 65Zn amount in the shoots of both types of transgenic Arabidopsis plants were higher than that in the WT. GSH concentration in phloem sap was increased significantly in WT with foliar applications of 10 mM GSH (WT-GSH), but not in transgenic Arabidopsis with elevated foliar GSH synthesis. Both types of transgenic Arabidopsis with elevated foliar GSH synthesis and WT-GSH exhibited increased shoot Zn concentrations and Zn translocation ratios. These results suggest that enhancement of endogenous foliar GSH synthesis and exogenous foliar GSH application affect root-to-shoot transport of Zn.

Glutathione (GSH) is a thiol-containing compound involved in many aspects of plant metabolism. In the present study, we investigated how enhancing endogenous and exogenous GSH affects cadmium (Cd) movement and distribution in Arabidopsis plants cultured hydroponically. Transgenic Arabidopsis plants with a strong ability to synthesize GSH in roots were generated by transforming the gene encoding the bifunctional γ-glutamylcysteine synthetase-glutathione synthetase enzyme from Streptococcus thermophiles (StGCS-GS). Enhancing endogenous and exogenous GSH decreased the Cd translocation ratio in different ways. Only exogenous GSH significantly inhibited Cd translocation from roots to shoots in wild-type and transgenic Arabidopsis plants. Our study demonstrated that GSH mainly functions outside root cells to inhibit Cd translocation from roots to shoots.

Glutathione (GSH) is a thiol-containing compound involved in many aspects of plant metabolism. In the present study, we investigated how enhancing endogenous and exogenous GSH affects cadmium (Cd) movement and distribution in Arabidopsis plants cultured hydroponically. Transgenic Arabidopsis plants with a strong ability to synthesize GSH in roots were generated by transforming the gene encoding the bifunctional γ-glutamylcysteine synthetase-glutathione synthetase enzyme from Streptococcus thermophiles (StGCS-GS). Enhancing endogenous and exogenous GSH decreased the Cd translocation ratio in different ways. Only exogenous GSH significantly inhibited Cd translocation from roots to shoots in wild-type and transgenic Arabidopsis plants. Our study demonstrated that GSH mainly functions outside root cells to inhibit Cd translocation from roots to shoots.