Abstract
The plant hormone abscisic acid (ABA) regulates important stress and developmental responses. We have isolated a recessive ABA hypersensitive mutant, abh1, that shows hormone specificity to ABA. ABH1 encodes the Arabidopsis homolog of a nuclear mRNA cap binding protein and functions in a heterodimeric complex to bind the mRNA cap structure. DNA chip analyses show that only a few transcripts are down-regulated in abh1, several of which are implicated in ABA signaling. Consistent with these results, abh1 plants show ABA-hypersensitive stomatal closing and reduced wilting during drought. Interestingly, ABA-hypersensitive cytosolic calcium increases in abh1 guard cells demonstrate amplification of early ABA signaling. Thus, ABH1 represents a modulator of ABA signaling proposed to function by transcript alteration of early ABA signaling elements.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Abscisic Acid / pharmacology*
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Arabidopsis / cytology
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Arabidopsis / genetics*
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Arabidopsis / physiology*
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Arabidopsis Proteins*
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Blotting, Northern
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Calcium / metabolism
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Epistasis, Genetic
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Genes, Reporter
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Humans
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Molecular Sequence Data
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Oligonucleotide Array Sequence Analysis
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Plant Growth Regulators / pharmacology
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RNA Cap-Binding Proteins
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RNA Caps / metabolism
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RNA-Binding Proteins / genetics
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RNA-Binding Proteins / metabolism*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Seeds / physiology
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Signal Transduction / physiology*
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Two-Hybrid System Techniques
Substances
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ABH1 protein, Arabidopsis
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Arabidopsis Proteins
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Plant Growth Regulators
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RNA Cap-Binding Proteins
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RNA Caps
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RNA-Binding Proteins
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Recombinant Fusion Proteins
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Abscisic Acid
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Calcium