Document Detail

Effects of intraleaf variations in carbonic anhydrase activity and gas exchange on leaf C18OO isoflux in Zea mays.
MedLine Citation:
PMID:  16411935     Owner:  NLM     Status:  MEDLINE    
Variation in the C18OO content of atmospheric CO2 (delta18Oa) can be used to distinguish photosynthesis from soil respiration, which is based on carbonic anhydrase (CA)-catalyzed 18O exchange between CO2 and 18O-enriched leaf water (delta18Ow). Here we tested the hypothesis that mean leaf delta18Ow and assimilation rates can be used to estimate whole-leaf C18OO flux (isoflux), ignoring intraleaf variations in CA activity and gas exchange parameters. We observed variations in CA activity along the leaf (> 30% decline from the leaf center toward the leaf ends), which were only partially correlated to those in delta18Ow (7 to 21 per thousand), delta18O and delta13C of leaf organic matter (25 to 30 per thousand and -12.8 to -13.2 per thousand, respectively), and substomatal CO2 concentrations (intercellular CO2 concentrations, c(i), at the leaf center were approximately 40% of those at the leaf tip). The combined effect of these variations produced a leaf-integrated isoflux that was different from that predicted based on bulk leaf values. However, because of canceling effects among the influencing parameters, isoflux overestimations were only approximately 10%. Conversely, use of measured parameters from a leaf segment could produce large errors in predicting leaf-integrated C18OO fluxes.
Hagit P Affek; Maria J Krisch; Dan Yakir
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The New phytologist     Volume:  169     ISSN:  0028-646X     ISO Abbreviation:  New Phytol.     Publication Date:  2006  
Date Detail:
Created Date:  2006-01-17     Completed Date:  2006-03-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9882884     Medline TA:  New Phytol     Country:  England    
Other Details:
Languages:  eng     Pagination:  321-9     Citation Subset:  IM    
Department of Environmental Sciences and Energy Research, Weizmann Institute, Rehovot 76100, Israel.
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MeSH Terms
Carbon / metabolism
Carbon Dioxide / metabolism*
Carbonic Anhydrases / metabolism*
Cell Respiration
Oxygen / metabolism
Oxygen Isotopes
Plant Leaves / enzymology*,  metabolism*
Plant Transpiration
Zea mays / enzymology*,  metabolism
Reg. No./Substance:
0/Oxygen Isotopes; 124-38-9/Carbon Dioxide; 7440-44-0/Carbon; 7782-44-7/Oxygen; EC Anhydrases

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