Effects of intraleaf variations in carbonic anhydrase activity and gas exchange on leaf C18OO isoflux in Zea mays

Hagit P. Affek, Maria J. Krisch, Dan Yakir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

• Variation in the C18OO content of atmospheric CO 218Oa) 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 (δ18Ow). • Here we tested the hypothesis that mean leaf δ18Ow 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 δ18Ow (7 to 21‰), δ18O and δ13C of leaf organic matter (25 to 30‰ and -12.8 to -13.2‰, respectively), and substomatal CO2 concentrations (intercellular CO2 concentrations, ci, at the leaf center were ∼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 ∼10%. Conversely, use of measured parameters from a leaf segment could produce large errors in predicting leaf-integrated C18OO fluxes.

Original languageEnglish
Pages (from-to)321-329
Number of pages9
JournalNew Phytologist
Volume169
Issue number2
DOIs
StatePublished - Jan 2006
Externally publishedYes

Keywords

  • Carbonic anhydrase
  • Intraleaf variations
  • Isoflux
  • O
  • O-CO
  • O-leaf water
  • Zea mays

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