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Overexpression of the transporters AtZIP1 and AtMTP1 in cassava changes zinc accumulation and partitioning.

Gaitán-Solís E, Taylor NJ, Siritunga D, Stevens W, Schachtman DP - Front Plant Sci (2015)

Bottom Line: Eighteen transgenic events from four constructs, out of a total of 73 events generated, showed significantly higher zinc concentrations in the edible portion of the storage root compared to the non-transgenic controls.The zinc content in the transgenic lines ranged from 4 to 73 mg/kg dry weight (DW) as compared to the non-transgenic control which contained 8 mg/kg.Striking changes in whole plant phenotype such as smaller plant size and chlorotic leaves were observed in transgenic lines that over accumulated zinc.

View Article: PubMed Central - PubMed

Affiliation: Donald Danforth Plant Science Center, St Louis, MO USA.

ABSTRACT
Zinc deficiency in humans is a serious problem worldwide with an estimated one third of populations at risk for insufficient zinc in diet, which leads to impairment of cognitive abilities and immune system function. The goal of this research was to increase the bioavailable zinc in the edible portion of cassava roots to improve the overall zinc nutrition of populations that rely on cassava as a dietary staple. To increase zinc concentrations, two Arabidopsis thaliana genes coding for ZIP1 and MTP1 were overexpressed with a tuber-specific or constitutive promoter. Eighteen transgenic events from four constructs, out of a total of 73 events generated, showed significantly higher zinc concentrations in the edible portion of the storage root compared to the non-transgenic controls. The zinc content in the transgenic lines ranged from 4 to 73 mg/kg dry weight (DW) as compared to the non-transgenic control which contained 8 mg/kg. Striking changes in whole plant phenotype such as smaller plant size and chlorotic leaves were observed in transgenic lines that over accumulated zinc. In a confined field trial five transgenic events grown for 12 months showed a range of zinc concentrations from 18 to 217 mg/kg DW. Although the overexpression of zinc transporters was successful in increasing the zinc concentrations in 25% of the transgenic lines generated, it also resulted in a decrease in plant and tuber size and overall yield due to what appears to be zinc deficiency in the aerial parts of the plant.

No MeSH data available.


Related in: MedlinePlus

Zinc concentration in the edible part of the storage roots (A,B) and leaves (C,D) of six independent transgenic PAT:AtMTP1, PAT:AtZIP1, and FMV:AtZIP1 events after 6–8 months of growth in a greenhouse soil bed. Data represent the mean zinc content normalized for DW of seven independent samples, error bars indicate SD. Comparison is between wild type and transgenic events and indicate the different levels of statistical significance ∗P < 0.05, ∗∗∗P < 0.001.
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Figure 4: Zinc concentration in the edible part of the storage roots (A,B) and leaves (C,D) of six independent transgenic PAT:AtMTP1, PAT:AtZIP1, and FMV:AtZIP1 events after 6–8 months of growth in a greenhouse soil bed. Data represent the mean zinc content normalized for DW of seven independent samples, error bars indicate SD. Comparison is between wild type and transgenic events and indicate the different levels of statistical significance ∗P < 0.05, ∗∗∗P < 0.001.

Mentions: In order to produce more mature plants with larger storage roots, transgenic lines from three constructs were established and grown in soil beds within a greenhouse at the University of Missouri, Portageville, MO, USA. Zinc levels in leaves and tuberous storage roots were assessed after 8 months of growth in the 50% of plants that formed tubers which included three zinc over accumulating transgenic lines from construct PAT:AtMTP1, two from PAT:AtZIP1 and one from FMV:AtZIP1. Soil bed grown plants showed significantly higher zinc concentration than the wild type control in their storage roots, with mean values ranging from 22 to 53 mg of zinc per kilogram dry weight (DW; Figures 4A,B). These zinc concentrations were more than twice that obtained from plants grown in pots in the growth chambers (Figure 1A). Zinc concentrations in leaves were significantly lower than the control for all three AtMTP1 expressing lines and in PAT:AtZIP1 line 294A and FMV:AtZIP1 line 8B (Figures 4A,B). These transgenic plant lines showed an approximate 50% reduction in leaf Zn levels compared to non-transgenic controls at 28–38 mg/kg DW zinc (Figures 4C,D).


Overexpression of the transporters AtZIP1 and AtMTP1 in cassava changes zinc accumulation and partitioning.

Gaitán-Solís E, Taylor NJ, Siritunga D, Stevens W, Schachtman DP - Front Plant Sci (2015)

Zinc concentration in the edible part of the storage roots (A,B) and leaves (C,D) of six independent transgenic PAT:AtMTP1, PAT:AtZIP1, and FMV:AtZIP1 events after 6–8 months of growth in a greenhouse soil bed. Data represent the mean zinc content normalized for DW of seven independent samples, error bars indicate SD. Comparison is between wild type and transgenic events and indicate the different levels of statistical significance ∗P < 0.05, ∗∗∗P < 0.001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496839&req=5

Figure 4: Zinc concentration in the edible part of the storage roots (A,B) and leaves (C,D) of six independent transgenic PAT:AtMTP1, PAT:AtZIP1, and FMV:AtZIP1 events after 6–8 months of growth in a greenhouse soil bed. Data represent the mean zinc content normalized for DW of seven independent samples, error bars indicate SD. Comparison is between wild type and transgenic events and indicate the different levels of statistical significance ∗P < 0.05, ∗∗∗P < 0.001.
Mentions: In order to produce more mature plants with larger storage roots, transgenic lines from three constructs were established and grown in soil beds within a greenhouse at the University of Missouri, Portageville, MO, USA. Zinc levels in leaves and tuberous storage roots were assessed after 8 months of growth in the 50% of plants that formed tubers which included three zinc over accumulating transgenic lines from construct PAT:AtMTP1, two from PAT:AtZIP1 and one from FMV:AtZIP1. Soil bed grown plants showed significantly higher zinc concentration than the wild type control in their storage roots, with mean values ranging from 22 to 53 mg of zinc per kilogram dry weight (DW; Figures 4A,B). These zinc concentrations were more than twice that obtained from plants grown in pots in the growth chambers (Figure 1A). Zinc concentrations in leaves were significantly lower than the control for all three AtMTP1 expressing lines and in PAT:AtZIP1 line 294A and FMV:AtZIP1 line 8B (Figures 4A,B). These transgenic plant lines showed an approximate 50% reduction in leaf Zn levels compared to non-transgenic controls at 28–38 mg/kg DW zinc (Figures 4C,D).

Bottom Line: Eighteen transgenic events from four constructs, out of a total of 73 events generated, showed significantly higher zinc concentrations in the edible portion of the storage root compared to the non-transgenic controls.The zinc content in the transgenic lines ranged from 4 to 73 mg/kg dry weight (DW) as compared to the non-transgenic control which contained 8 mg/kg.Striking changes in whole plant phenotype such as smaller plant size and chlorotic leaves were observed in transgenic lines that over accumulated zinc.

View Article: PubMed Central - PubMed

Affiliation: Donald Danforth Plant Science Center, St Louis, MO USA.

ABSTRACT
Zinc deficiency in humans is a serious problem worldwide with an estimated one third of populations at risk for insufficient zinc in diet, which leads to impairment of cognitive abilities and immune system function. The goal of this research was to increase the bioavailable zinc in the edible portion of cassava roots to improve the overall zinc nutrition of populations that rely on cassava as a dietary staple. To increase zinc concentrations, two Arabidopsis thaliana genes coding for ZIP1 and MTP1 were overexpressed with a tuber-specific or constitutive promoter. Eighteen transgenic events from four constructs, out of a total of 73 events generated, showed significantly higher zinc concentrations in the edible portion of the storage root compared to the non-transgenic controls. The zinc content in the transgenic lines ranged from 4 to 73 mg/kg dry weight (DW) as compared to the non-transgenic control which contained 8 mg/kg. Striking changes in whole plant phenotype such as smaller plant size and chlorotic leaves were observed in transgenic lines that over accumulated zinc. In a confined field trial five transgenic events grown for 12 months showed a range of zinc concentrations from 18 to 217 mg/kg DW. Although the overexpression of zinc transporters was successful in increasing the zinc concentrations in 25% of the transgenic lines generated, it also resulted in a decrease in plant and tuber size and overall yield due to what appears to be zinc deficiency in the aerial parts of the plant.

No MeSH data available.


Related in: MedlinePlus