Abstract
Given their sessile nature, land plants must use various mechanisms to manage dehydration under water-deficit conditions. Osmostress-induced activation of the SNF1-related protein kinase 2 (SnRK2) family elicits physiological responses such as stomatal closure to protect plants during drought conditions. With the plant hormone ABA receptors [PYR (pyrabactin resistance)/PYL (pyrabactin resistance-like)/RCAR (regulatory component of ABA receptors) proteins] and group A protein phosphatases, subclass III SnRK2 also constitutes a core signaling module for ABA, and osmostress triggers ABA accumulation. How SnRK2 is activated through ABA has been clarified, although its activation through osmostress remains unclear. Here, we show that Arabidopsis ABA and abiotic stress-responsive Raf-like kinases (AtARKs) of the B3 clade of the mitogen-activated kinase kinase kinase (MAPKKK) family are crucial in SnRK2-mediated osmostress responses. Disruption of AtARKs in Arabidopsis results in increased water loss from detached leaves because of impaired stomatal closure in response to osmostress. Our findings obtained in vitro and in planta have shown that AtARKs interact physically with SRK2E, a core factor for stomatal closure in response to drought. Furthermore, we show that AtARK phosphorylates S171 and S175 in the activation loop of SRK2E in vitro and that Atark mutants have defects in osmostress-induced subclass III SnRK2 activity. Our findings identify a specific type of B3-MAPKKKs as upstream kinases of subclass III SnRK2 in Arabidopsis. Taken together with earlier reports that ARK is an upstream kinase of SnRK2 in moss, an existing member of a basal land plant lineage, we propose that ARK/SnRK2 module is evolutionarily conserved across 400 million years of land plant evolution for conferring protection against drought.
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Claims 6
Claim · model-written summary
Disruption of AtARKs increased water loss from detached leaves because of impaired stomatal closure under osmostress
- Taxon
- Arabidopsis
Arabidopsist0 - Treatment
- Disruption of AtARKse0
- Gene
- AtARKse0
- Outcome
- water loss from detached leavese0
- Direction
- increasede0
- Qualifier
- impaired stomatal closure in response to osmostresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis Raf‐like kinases act as positive regulators of subclass III SnRK2 in osmostress signaling”
e0“Disruption of AtARKs in Arabidopsis results in increased water loss from detached leaves because of impaired stomatal closure in response to osmostress”
Claim · model-written summary
AtARKs physically interact with SRK2E in vitro and in planta
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AtARKse1
- Outcome
- interact physicallye1
- Qualifier
- with SRK2Ee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis Raf‐like kinases act as positive regulators of subclass III SnRK2 in osmostress signaling”
e1“AtARKs interact physically with SRK2E”
Claim · model-written summary
AtARK phosphorylates S171 and S175 in the activation loop of SRK2E in vitro
- Taxon
- ArabidopsisArabidopsist0
- Gene
- SRK2Ee2
- Outcome
- phosphorylates S171 and S175e2
- Qualifier
- in vitroe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis Raf‐like kinases act as positive regulators of subclass III SnRK2 in osmostress signaling”
e2“AtARK phosphorylates S171 and S175 in the activation loop of SRK2E in vitro”
Claim · model-written summary
Atark mutants had reduced osmostress-induced subclass III SnRK2 activity
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atark mutantse3
- Treatment
- osmostresse3
- Outcome
- subclass III SnRK2 activitye3
- Direction
- decreaseinferrede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis Raf‐like kinases act as positive regulators of subclass III SnRK2 in osmostress signaling”
e3“Atark mutants have defects in osmostress-induced subclass III SnRK2 activity”
Claim · model-written summary
A specific type of B3-MAPKKKs is an upstream kinase of subclass III SnRK2 in Arabidopsis
- Taxon
- ArabidopsisArabidopsist0
- Gene
- B3-MAPKKKse4
- Outcome
- upstream kinases of subclass III SnRK2e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis Raf‐like kinases act as positive regulators of subclass III SnRK2 in osmostress signaling”
e4“Our findings identify a specific type of B3-MAPKKKs as upstream kinases of subclass III SnRK2 in Arabidopsis”
Claim · model-written summary
The ARK/SnRK2 module is proposed to be evolutionarily conserved across land plants for drought protection
Verbatim
e5“we propose that ARK/SnRK2 module is evolutionarily conserved across 400 million years of land plant evolution for conferring protection against drought”
The same questions in other papers
loss of function · physiology: water · ArabidopsisPositive and negative results
3 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- negative
2 papers more in this group
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