Identification of the Bacterial Alarmone Guanosine 5′-Diphosphate 3′-Diphosphate (ppGpp) in Plants

Stringent control mediated by the bacterial alarmone guanosine 5′-diphosphate 3′-diphosphate (ppGpp) is a key regulatory process governing bacterial gene expression. By devising a system to measure ppGpp in plants, we have been able to identify ppGpp in the chloroplasts of plant cells. Levels of ppG...

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Published in:Proceedings of the National Academy of Sciences - PNAS 2004-03, Vol.101 (12), p.4320-4324
Main Authors: Takahashi, Kosaku, Kasai, Koji, Ochi, Kozo, Ausubel, Frederick M.
Format: Article
Language:English
Subjects:
Bacteria
Biological Sciences
Botany
Chloroplasts
Chloroplasts - enzymology
Chloroplasts - metabolism
Chromatography, High Pressure Liquid
DNA-Directed RNA Polymerases - antagonists & inhibitors
DNA-Directed RNA Polymerases - metabolism
Drought
Gene expression
Guanosine Tetraphosphate - analysis
Guanosine Tetraphosphate - biosynthesis
Hormones
Lighting
Nucleotides
Peas
Plant cells
Plant growth regulators
Plant Growth Regulators - metabolism
Plants - chemistry
Plants - metabolism
RNA
Signaling
Spectrophotometry, Ultraviolet
Stress
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Summary:Stringent control mediated by the bacterial alarmone guanosine 5′-diphosphate 3′-diphosphate (ppGpp) is a key regulatory process governing bacterial gene expression. By devising a system to measure ppGpp in plants, we have been able to identify ppGpp in the chloroplasts of plant cells. Levels of ppGpp increased markedly when plants were subjected to such biotic and abiotic stresses as wounding, heat shock, high salinity, acidity, heavy metal, drought, and UV irradiation. Abrupt changes from light to dark also caused a substantial elevation in ppGpp levels. In vitro, chloroplast RNA polymerase activity was inhibited in the presence of ppGpp, demonstrating the existence of a bacteria-type stringent response in plants. Elevation of ppGpp levels was elicited also by treatment with plant hormones jasmonic acid, abscisic acid, and ethylene, but these effects were blocked completely by another plant hormone, indole-3-acetic acid. On the basis of these findings, we propose that ppGpp plays a critical role in systemic plant signaling in response to environmental stresses, contributing to the adaptation of plants to environmental changes.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0308555101