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A nucleotide metabolite controls stress-responsive gene expression and plant development
Hao Chen1, Baichen Zhang, Leslie M Hicks
1Donald Danforth Plant Science Center, St Louis, Missouri, United States of America.
Plos One
|October 27, 2011
Summary
The plant enzyme FIERY1 (FRY1) degrades 3'-phosphoadenosine-5'-phosphate (PAP). High PAP levels in fry1 mutants cause developmental defects and altered stress gene expression, indicating PAP
Area of Science:
- Plant molecular biology
- Stress signaling pathways
- Biochemistry
Background:
- Abiotic stresses trigger plant signaling cascades and stress-responsive gene expression.
- The Arabidopsis FIERY1 (FRY1) protein negatively regulates stress and abscisic acid (ABA) signaling.
- FRY1 possesses in vitro nucleotidase activity, degrading 3 -phosphoadenosine-5 -phosphate (PAP), but its in vivo function is unclear.
Purpose of the Study:
- To quantitatively measure PAP levels in plants using LC-MS/MS.
- To investigate the in vivo roles of FRY1 nucleotidase activity in plant stress response and development.
- To elucidate the relationship between PAP accumulation and observed phenotypes in FRY1 mutants.
Main Methods:
- Development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantitative PAP measurement.
- Analysis of PAP levels in wild-type and various mutant Arabidopsis lines under normal and stress conditions (NaCl, LiCl, cold, ABA).
- Genetic manipulation of PAP levels in fry1 mutants via yeast PAP nucleotidase overexpression and generation of a PAPS biosynthesis triple mutant (fry1 apk1 apk2).
Main Results:
- PAP levels are tightly controlled in wild-type plants and do not accumulate significantly under various stress conditions.
- High PAP levels were detected specifically in multiple fry1 mutant alleles, identifying FRY1 as the primary in vivo PAP-degrading enzyme.
- Reducing PAP levels in fry1 mutants ameliorated developmental defects and normalized stress-responsive gene superinduction, directly linking PAP accumulation to these phenotypes.
- Hypersensitive stress gene regulation in fry1 mutants requires ABH1 but not ABI1.
- FRY1 overexpression did not enhance salt tolerance in Arabidopsis.
Conclusions:
- PAP is a critical molecule regulating plant development and stress-responsive gene expression.
- The FRY1 nucleotidase's role in degrading PAP is essential for preventing developmental abnormalities and aberrant gene expression.
- While FRY1 is the key enzyme for PAP degradation, it may not be a direct target for salt toxicity mitigation in Arabidopsis.
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