Document Detail


Induction of a longer term component of isoprene release in darkened aspen leaves: origin and regulation under different environmental conditions.
MedLine Citation:
PMID:  21502186     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
After darkening, isoprene emission continues for 20 to 30 min following biphasic kinetics. The initial dark release of isoprene (postillumination emission), for 200 to 300 s, occurs mainly at the expense of its immediate substrate, dimethylallyldiphosphate (DMADP), but the origin and controls of the secondary burst of isoprene release (dark-induced emission) between approximately 300 and 1,500 s, are not entirely understood. We used a fast-response gas-exchange system to characterize the controls of dark-induced isoprene emission by light, temperature, and CO(2) and oxygen concentrations preceding leaf darkening and the effects of short light pulses and changing gas concentrations during dark-induced isoprene release in hybrid aspen (Populus tremula × Populus tremuloides). The effect of the 2-C-methyl-D-erythritol-4-phosphate pathway inhibitor fosmidomycin was also investigated. The integral of postillumination isoprene release was considered to constitute the DMADP pool size, while the integral of dark-induced emission was defined as the "dark" pool. Overall, the steady-state emission rate in light and the maximum dark-induced emission rate responded similarly to variations in preceding environmental drivers and atmospheric composition, increasing with increasing light, having maxima at approximately 40 °C and close to the CO(2) compensation point, and were suppressed by lack of oxygen. The DMADP and dark pool sizes were also similar through their environmental dependencies, except for high temperatures, where the dark pool significantly exceeded the DMADP pool. Isoprene release could be enhanced by short lightflecks early during dark-induced isoprene release, but not at later stages. Fosmidomycin strongly suppressed both the isoprene emission rates in light and in the dark, but the dark pool was only moderately affected. These results demonstrate a strong correspondence between the steady-state isoprene emission in light and the dark-induced emission and suggest that the dark pool reflects the total pool size of 2-C-methyl-d-erythritol-4-phosphate pathway metabolites upstream of DMADP. These metabolites are converted to isoprene as soon as ATP and NADPH become available, likely by dark activation of chloroplastic glycolysis and chlororespiration.
Authors:
Bahtijor Rasulov; Katja Hüve; Agu Laisk; Ülo Niinemets
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-04-18
Journal Detail:
Title:  Plant physiology     Volume:  156     ISSN:  1532-2548     ISO Abbreviation:  Plant Physiol.     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-06-02     Completed Date:  2011-09-26     Revised Date:  2011-09-30    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  816-31     Citation Subset:  IM    
Affiliation:
Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia.
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MeSH Terms
Descriptor/Qualifier:
Butadienes / analysis*
Carbon Dioxide / pharmacology
Darkness*
Environment*
Fosfomycin / analogs & derivatives,  pharmacology
Hemiterpenes / analysis*
Kinetics
Models, Biological
Oxygen / pharmacology
Pentanes / analysis*
Plant Leaves / drug effects,  physiology*
Populus / drug effects,  physiology*
Temperature
Time Factors
Chemical
Reg. No./Substance:
0/Butadienes; 0/Hemiterpenes; 0/Pentanes; 124-38-9/Carbon Dioxide; 23155-02-4/Fosfomycin; 66508-53-0/fosmidomycin; 7782-44-7/Oxygen; 78-79-5/isoprene

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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