Abstract
Metal accumulation in seeds is a prerequisite for germination and establishment of plants but also for micronutrient delivery to humans. To investigate metal transport processes and their interactions in seeds, we focused on METAL TOLERANCE PROTEIN8 (MTP8), a tonoplast transporter of the manganese (Mn) subclade of cation diffusion facilitators, which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds. The x-ray fluorescence imaging showed that expression of MTP8 was responsible for Mn localization in subepidermal cells on the abaxial side of the cotyledons and in cortical cells of the hypocotyl. Accordingly, under low Mn availability, MTP8 increased seed stores of Mn, required for efficient seed germination. In mutant embryos lacking expression of VACUOLAR IRON TRANSPORTER1 (VIT1), MTP8 built up iron (Fe) hotspots in MTP8-expressing cells types, suggesting that MTP8 transports Fe in addition to Mn. In mtp8 vit1 double mutant seeds, Mn and Fe were distributed in all cell types of the embryo. An Fe transport function of MTP8 was confirmed by its ability to complement Fe hypersensitivity of a yeast mutant defective in vacuolar Fe transport. Imbibing mtp8-1 mutant seeds in the presence of Mn or subjecting seeds to wet-dry cycles showed that MTP8 conferred Mn tolerance. During germination, MTP8 promoted reallocation of Fe from the vasculature. These results indicate that cell type-specific accumulation of Mn and Fe in seeds depends on MTP8 and that this transporter plays an important role in the generation of seed metal stores as well as for metal homeostasis and germination efficiency under challenging environmental conditions.
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Claims 9
Claim · model-written summary
MTP8 expression is responsible for Mn localization in subepidermal cells on the abaxial side of the cotyledons and in cortical cells of the hypocotyl.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Organ / stage
- subepidermal cells on the abaxial side of the cotyledonse1
- Gene
- MTP8e1
- Outcome
- Mn localizatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e1“The x-ray fluorescence imaging showed that expression of MTP8 was responsible for Mn localization in subepidermal cells on the abaxial side of the cotyledons and in cortical cells of the hypocotyl”
Claim · model-written summary
Under low Mn availability, MTP8 increased seed stores of Mn.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- low Mn availabilitye2
- Gene
- MTP8e2
- Outcome
- seed stores of Mne2
- Direction
- increasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e2“under low Mn availability, MTP8 increased seed stores of Mn, required for efficient seed germination”
Claim · model-written summary
Seed Mn stores were required for efficient seed germination.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Outcome
- efficient seed germinatione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e2“under low Mn availability, MTP8 increased seed stores of Mn, required for efficient seed germination”
Claim · model-written summary
In mutant embryos lacking VIT1 expression, MTP8 built up Fe hotspots in MTP8-expressing cell types.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Material
- mutant embryos lacking expression of VACUOLAR IRON TRANSPORTER1 (VIT1)e3
- Organ / stage
- embryose3
- Gene
- MTP8e3
- Outcome
- iron (Fe) hotspotse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e3“In mutant embryos lacking expression of VACUOLAR IRON TRANSPORTER1 (VIT1), MTP8 built up iron (Fe) hotspots in MTP8-expressing cells types, suggesting that MTP8 transports Fe in addition to Mn”
Claim · model-written summary
MTP8 transports Fe in addition to Mn.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Gene
- MTP8e3
- Outcome
- transports Fe in addition to Mne3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e3“In mutant embryos lacking expression of VACUOLAR IRON TRANSPORTER1 (VIT1), MTP8 built up iron (Fe) hotspots in MTP8-expressing cells types, suggesting that MTP8 transports Fe in addition to Mn”
Claim · model-written summary
In mtp8 vit1 double mutant seeds, Mn and Fe were distributed in all cell types of the embryo.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Material
- mtp8 vit1 double mutant seedse4
- Outcome
- Mn and Fe were distributed in all cell types of the embryoe4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e4“In mtp8 vit1 double mutant seeds, Mn and Fe were distributed in all cell types of the embryo”
Claim · model-written summary
MTP8 complemented Fe hypersensitivity of a yeast mutant defective in vacuolar Fe transport.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Material
- yeast mutant defective in vacuolar Fe transporte5
- Gene
- MTP8e5
- Outcome
- ability to complement Fe hypersensitivitye5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e5“An Fe transport function of MTP8 was confirmed by its ability to complement Fe hypersensitivity of a yeast mutant defective in vacuolar Fe transport”
Claim · model-written summary
MTP8 conferred Mn tolerance on imbibing mtp8-1 mutant seeds in the presence of Mn or under wet-dry cycles.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Material
- mtp8-1 mutant seedse6
- Treatment
- in the presence of Mn or subjecting seeds to wet-dry cyclese6
- Gene
- MTP8e6
- Outcome
- Mn tolerancee6
- Direction
- increaseinferrede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e6“Imbibing mtp8-1 mutant seeds in the presence of Mn or subjecting seeds to wet-dry cycles showed that MTP8 conferred Mn tolerance”
Claim · model-written summary
During germination, MTP8 promoted reallocation of Fe from the vasculature.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Organ / stage
- vasculaturee7
- Gene
- MTP8e7
- Outcome
- reallocation of Fe from the vasculaturee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds”
e7“During germination, MTP8 promoted reallocation of Fe from the vasculature”
The same questions in other papers
manganese atom · nutrient: content · Arabidopsis thaliana (thale cress)Positive and negative results
1 in the opposite direction
This paper is about lacking the nutrient, so it counts the other way round here.
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.