Abstract
Cytokinins are plant hormones with profound roles in growth and development, including control of leaf longevity. Although the cytokinin signal is known to be perceived by histidine kinase receptors, the underlying molecular mechanism and specificity of the receptors leading to delayed leaf senescence have not yet been elucidated. Here, we found that AHK3, one of the three cytokinin receptors in Arabidopsis, plays a major role in controlling cytokinin-mediated leaf longevity through a specific phosphorylation of a response regulator, ARR2. This result was obtained through identification of a gain-of-function Arabidopsis mutant that shows delayed leaf senescence because of a missense mutation in the extracellular domain of AHK3. A loss-of-function mutation in AHK3, but not of the other cytokinin receptors, conferred a reduced sensitivity to cytokinin in cytokinin-dependent delay of leaf senescence and abolished cytokinin-dependent phosphorylation of ARR2. Consistently, transgenic overexpression of wild-type, but not an unphosphorylatable mutant ARR2, led to delayed senescence of leaves.
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Claims 5
Claim · model-written summary
AHK3 controlled cytokinin-mediated leaf longevity through ARR2 phosphorylation.
- Taxon
- Arabidopsis
Arabidopsise0 - Gene
- AHK3e0
- Outcome
- cytokinin-mediated leaf longevitye0
- Qualifier
- specific phosphorylation of a response regulator, ARR2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AHK3, one of the three cytokinin receptors in Arabidopsis, plays a major role in controlling cytokinin-mediated leaf longevity through a specific phosphorylation of a response regulator, ARR2”
Claim · model-written summary
An AHK3 gain-of-function mutant showed delayed leaf senescence.
- Taxon
- ArabidopsisArabidopsise0
- Material
- gain-of-function Arabidopsis mutante0
- Organ / stage
- leafe0
- Gene
- AHK3e0
- Outcome
- delayed leaf senescencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gain-of-function Arabidopsis mutant that shows delayed leaf senescence because of a missense mutation in the extracellular domain of AHK3”
Claim · model-written summary
AHK3 loss of function reduced sensitivity to cytokinin-mediated delay of leaf senescence.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- A loss-of-function mutation in AHK3e0
- Gene
- AHK3e0
- Outcome
- sensitivity to cytokinin in cytokinin-dependent delay of leaf senescencee0
- Direction
- reducede0
- Comparator
- the other cytokinin receptorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A loss-of-function mutation in AHK3, but not of the other cytokinin receptors, conferred a reduced sensitivity to cytokinin in cytokinin-dependent delay of leaf senescence”
e1“Arabidopsis mutant”
Claim · model-written summary
AHK3 loss of function abolished cytokinin-dependent ARR2 phosphorylation.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- A loss-of-function mutation in AHK3e0
- Gene
- ARR2e0
- Outcome
- cytokinin-dependent phosphorylation of ARR2e0
- Direction
- abolishede0
- Comparator
- the other cytokinin receptorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A loss-of-function mutation in AHK3, but not of the other cytokinin receptors, conferred a reduced sensitivity to cytokinin in cytokinin-dependent delay of leaf senescence and abolished cytokinin-dependent phosphorylation of ARR2”
e1“Arabidopsis mutant”
Claim · model-written summary
Wild-type ARR2 overexpression delayed leaf senescence, unlike unphosphorylatable ARR2.
- Taxon
- ArabidopsisArabidopsise1
- Treatment
- transgenic overexpression of wild-typee0
- Gene
- ARR2e0
- Outcome
- senescence of leavese0
- Direction
- delayede0
- Comparator
- an unphosphorylatable mutant ARR2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transgenic overexpression of wild-type, but not an unphosphorylatable mutant ARR2, led to delayed senescence of leaves”
e1“Arabidopsis mutant”
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