Dataset Information

BHLH Transcription Factors that Facilitate K+ Uptake During Stomatal Opening are Repressed by Abscisic Acid through Phosphorylation

ABSTRACT: Stomata open in response to light and close following exposure to abscisic acid (ABA). They regulate gas exchange between plants and atmosphere, allowing plants to adapt to changing environmental conditions. ABA binding to receptors initiates a signaling cascade that involves protein phosphorylation. Here we show that ABA induced phosphorylation of three basic helix-loop-helix (bHLH) transcription factors, called AKSs (ABA-RESPONSIVE KINASE SUBSTRATES; AKS1, AKS2, AKS3), in Arabidopsis guard cells, and that they facilitated stomatal opening through the transcription of genes encoding inwardly-rectifying K+ channels. aks1aks2-1 double mutant plants showed decreases in light-induced stomatal opening, K+ accumulation in response to light, activity of inwardly-rectifying K+ channels, and transcription of genes encoding major inwardly-rectifying K+ channels without affecting ABA-mediated stomatal closure. Overexpression of POTASSIUM CHANNEL IN ARABIDOPSIS THALIANA 1 (KAT1), which encodes a major inwardly-rectifying K+ channel in guard cells, rescued the phenotype of aks1aks2-1 plants. AKS1 bound directly to the promoter of KAT1, an interaction that was attenuated after ABA-induced phosphorylation. The ABA agonist pyrabactin induced phosphorylation of AKSs. Our results demonstrate that the AKS family of bHLH transcription factors facilitates stomatal opening through transcription of genes encoding inwardly-rectifying K+ channels, and that ABA suppresses the activity of inwardly-rectifying K+ channel activity by triggering the phosphorylation of these transcription factors. Microarray data have been deposited in the Gene Expression Omnibus with accession number: GSE46574.

OTHER RELATED OMICS DATASETS IN: PRJNA201022

INSTRUMENT(S): instrument model, LTQ

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Plant Cell

SUBMITTER: Y Takahashi

PROVIDER: PXD000235 | Pride | 2013-06-28

REPOSITORIES: Pride

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Publications

bHLH transcription factors that facilitate K⁺ uptake during stomatal opening are repressed by abscisic acid through phosphorylation.

Takahashi Yohei Y Ebisu Yuta Y Kinoshita Toshinori T Doi Michio M Okuma Eiji E Murata Yoshiyuki Y Shimazaki Ken-Ichiro K

Science signaling 20130618 280

Stomata open in response to light and close after exposure to abscisic acid (ABA). They regulate gas exchange between plants and the atmosphere, enabling plants to adapt to changing environmental conditions. ABA binding to receptors initiates a signaling cascade that involves protein phosphorylation. We show that ABA induced the phosphorylation of three basic helix-loop-helix (bHLH) transcription factors, called AKSs (ABA-responsive kinase substrates; AKS1, AKS2, and AKS3), in Arabidopsis guard ...[more]

PMID: 23779086

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Project description:Stomata are pores in the epidermis of plants that can open and close and allow for gas exchange vital for photosynthesis and regulate transpiration. Stomatal development is driven by a set of conserved bHLH transcription factors (SPCH, MUTE, FAMA, and their heterodimerization partners ICE1, SCRM2), that initiate and promote progression of cell fates in the stomatal lineage. Due to the shared ancestry of SPCH, MUTE and FAMA (subgroup Ia) and ICE1 and SCRM2 (subgroup IIIb) their DNA binding specificity is similar and there is some functional redundancy. However, individual bHLHs also have unique functions. For example, SPCH is required for initiation of the stomatal lineage, while FAMA is responsible for terminal differentiation of the guard cell pair. In grasses, the stomatal complex comprises the guard cell pair, and two flanking subsidiary cells. Recruitment of the latter from neighboring cell filed during development requires expression of MUTE. Remarkably, while MUTE is absolutely required for the promotion of guard mother cell fate in maize and rice, this is not the case in Brachypodium. This suggests that another TF can at least partially substitute for MUTE in this function. While different expression profiles of the bHLH dimers within the stomatal lineage may partially responsible for distinct functions of each pair, it is likely that each pair forms different transcriptional complexes and that interaction with other transcriptional regulators affects the dimer’s binding DNA binding and gene regulation properties. Given the differences in bHLH function between dicots and grasses and even within the grass family, we were interested in elucidating the protein interaction networks of the stomatal lineage regulators in Brachypodium. To this end, we performed co-immunoprecipitation coupled to LC-MS/MS of BdSPCH2-YFP, YFP-BdMUTE, YFP-BdFAMA, YFP-ICE1 and YFP-SCRM2 from the developmental zone of young B. distachyon leaves using GFP-Trap beads. All YFP-fusion proteins were expressed under the endogenous promoter in the Bd21-3 background. The only exception was BdICE1, which was expressed under the ZmUBI promoter, but was nevertheless mostly restricted to the stomatal lineage. As control lines we use the Bd21-3 wild type and a line expressing 3x YFPnls (nuclear YFP) under the MUTE promoter. Comparison of proteins enriched with the bHLH fusion proteins vs. the controls revealed overlapping and distinct putative interactors, which is in agreement with the assumption that these transcription factors have both shared and unique functions. Notably, in addition to the presumed hetero-dimerization partners, we found a number of other bHLH transcription factors that were identified with one or more of the bait proteins. This suggests the presence of a larger bHLH network acting in the stomatal lineage.

Dataset Information

BHLH Transcription Factors that Facilitate K+ Uptake During Stomatal Opening are Repressed by Abscisic Acid through Phosphorylation

Publications

bHLH transcription factors that facilitate K⁺ uptake during stomatal opening are repressed by abscisic acid through phosphorylation.

Similar Datasets

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