Abstract
The plant phytohormone cytokinin plays an important role in many facets of plant growth and development by regulating cell division and differentiation. Recent studies have shed significant light into the mechanisms of cytokinin metabolism and signaling. However, little is known about how the hormone is transported in planta, although it has been proposed that the hormone is presumably transported in nucleoside-conjugated forms. Here, we report the identification and characterization of cytokinin transport ers in Arabidopsis. We previously reported that a gain-of-function mutation in the PGA22/AtIPT8 gene caused overproduction of cytokinins in planta. In an effort to screen for suppressor of pga22/atipt8 (soi) mutants, we identified a mutant soi33-1. Molecular and genetic analyses indicated that SOI33 encodes a putative equilibrative nucleoside transporter (ENT), previously designated as AtENT8. Members of this small gene family are presumed to be involved in the transport of nucleosides in eukaryotic cells. Under conditions of nitrogen starvation, loss-of-function mutations in SOI33/AtENT8 or in a related gene AtENT3 cause a reduced sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans zeatin riboside (tZR), but display a normal response to the free base-type cytokinins isopentenyladenine (iP) and trans-zeatin (tZ). Conversely, overexpression of SOI33/AtENT8 renders transgenic plants hyper sensitive to iPR but not to iP. An in planta measurement experiment indicated that uptake efficiency of 3H labeled iPR was reduced more than 40% in soi33 and atent3 mutants. However, a mutation inAtENT1 had no substantial effect on the cytokinin response and iPR uptake efficiency. Our results suggest that SOI33/ AtENT8 and AtENT3 are involved in the transport of nucleoside-type cytokinins in Arabidopsis.
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Claims 10
Claim · model-written summary
SOI33 encodes a putative equilibrative nucleoside transporter previously designated AtENT8.
- Taxon
- Arabidopsis
Arabidopsise1 - Gene
- SOI33e0
- Outcome
- putative equilibrative nucleoside transporter (ENT)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SOI33 encodes a putative equilibrative nucleoside transporter (ENT), previously designated as AtENT8”
e1“transport ers in Arabidopsis”
Claim · model-written summary
SOI33/AtENT8 loss of function reduced sensitivity to nucleoside-type cytokinins under nitrogen starvation.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- loss-of-function mutations in SOI33/AtENT8e0
- Gene
- SOI33/AtENT8e0
- Outcome
- sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans zeatin riboside (tZR)e0
- Direction
- reducede0
- Qualifier
- nitrogen starvatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under conditions of nitrogen starvation, loss-of-function mutations in SOI33/AtENT8 or in a related gene AtENT3 cause a reduced sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans zeatin riboside (tZR)”
e1“transport ers in Arabidopsis”
Claim · model-written summary
AtENT3 loss of function reduced sensitivity to nucleoside-type cytokinins under nitrogen starvation.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- loss-of-function mutations in SOI33/AtENT8 or in a related gene AtENT3e0
- Gene
- AtENT3e0
- Outcome
- sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans zeatin riboside (tZR)e0
- Direction
- reducede0
- Qualifier
- nitrogen starvatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under conditions of nitrogen starvation, loss-of-function mutations in SOI33/AtENT8 or in a related gene AtENT3 cause a reduced sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans zeatin riboside (tZR)”
e1“transport ers in Arabidopsis”
Claim · model-written summary
The transporter mutants retained normal response to free-base cytokinins.
- Taxon
- ArabidopsisArabidopsise2
- Treatment
- SOI33/AtENT8 or in a related gene AtENT3e1
- Outcome
- response to the free base-type cytokinins isopentenyladenine (iP) and trans-zeatin (tZ)e0
- Direction
- normale0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but display a normal response to the free base-type cytokinins isopentenyladenine (iP) and trans-zeatin (tZ)”
e1“SOI33/AtENT8 or in a related gene AtENT3”
e2“transport ers in Arabidopsis”
Claim · model-written summary
SOI33/AtENT8 overexpression produced hypersensitivity to iPR.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- overexpression of SOI33/AtENT8e0
- Gene
- SOI33/AtENT8e0
- Outcome
- sensitive to iPRe0
- Direction
- hyper sensitivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overexpression of SOI33/AtENT8 renders transgenic plants hyper sensitive to iPR but not to iP”
e1“transport ers in Arabidopsis”
Claim · model-written summary
SOI33/AtENT8 overexpression did not cause hypersensitivity to iP.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- overexpression of SOI33/AtENT8e0
- Gene
- SOI33/AtENT8e0
- Outcome
- iPe0
- Direction
- not toe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overexpression of SOI33/AtENT8 renders transgenic plants hyper sensitive to iPR but not to iP”
e1“transport ers in Arabidopsis”
Claim · model-written summary
iPR uptake efficiency fell more than 40% in soi33 mutants.
- Taxon
- ArabidopsisArabidopsise1
- Material
- soi33e0
- Treatment
- soi33e0
- Outcome
- uptake efficiency of 3H labeled iPRe0
- Direction
- reducede0
- Value
- more than 40%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“uptake efficiency of 3H labeled iPR was reduced more than 40% in soi33 and atent3 mutants”
e1“transport ers in Arabidopsis”
Claim · model-written summary
iPR uptake efficiency fell more than 40% in atent3 mutants.
- Taxon
- ArabidopsisArabidopsise1
- Material
- atent3e0
- Treatment
- atent3e0
- Outcome
- uptake efficiency of 3H labeled iPRe0
- Direction
- reducede0
- Value
- more than 40%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“uptake efficiency of 3H labeled iPR was reduced more than 40% in soi33 and atent3 mutants”
e1“transport ers in Arabidopsis”
Claim · model-written summary
AtENT1 mutation had no substantial effect on cytokinin response or iPR uptake.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- a mutation inAtENT1e0
- Gene
- AtENT1e0
- Outcome
- cytokinin response and iPR uptake efficiencye0
- Direction
- no substantial effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a mutation inAtENT1 had no substantial effect on the cytokinin response and iPR uptake efficiency”
e1“transport ers in Arabidopsis”
Claim · model-written summary
The authors infer SOI33/AtENT8 and AtENT3 transport nucleoside-type cytokinins.
- Taxon
- ArabidopsisArabidopsise0
- Gene
- SOI33/ AtENT8 and AtENT3e0
- Outcome
- transport of nucleoside-type cytokininse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SOI33/ AtENT8 and AtENT3 are involved in the transport of nucleoside-type cytokinins in Arabidopsis”
The same questions in other papers
loss of function · physiology: hormones · ArabidopsisPositive and negative results
51 papers in the same direction as this paper · 8 in the opposite direction
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