Improving plant productivity is an important aim for metabolic engineering. There are few comprehensive methods that quantitatively describe leaf metabolism, although such information would be valuable for increasing photosynthetic capacity, enhancing biomass production, and rerouting @entity505 flux toward desirable end products. Isotopically nonstationary metabolic flux analysis (INST-MFA) has been previously applied to map @entity505 fluxes in photoautotrophic bacteria, which involves model-based regression of transient @entity7352 -labeling patterns of intracellular metabolites. However, experimental and computational difficulties have hindered its application to terrestrial plant systems. We performed in vivo isotopic labeling of @entity958 rosettes with (13)CO2 and estimated fluxes throughout leaf photosynthetic metabolism by INST-MFA. Plants grown at 200   mol m(-2)s(-1) light were compared with plants acclimated for 9 d at an irradiance of 500   mol   m(-2)   s(-1). Approximately 1,400 independent mass isotopomer measurements obtained from analysis of 37 metabolite fragment ions were regressed to estimate 136 total fluxes (54 free fluxes) under each condition. The results provide a comprehensive description of changes in @entity505 partitioning and overall photosynthetic flux after long-term developmental acclimation of leaves to high light. Despite a doubling in the carboxylation rate, the photorespiratory flux increased from 17 to 28% of net @entity515 assimilation with high-light acclimation (Vc/Vo: 3.5:1 vs. 2.3:1, respectively). This study highlights the potential of @entity7352 INST-MFA to describe emergent flux phenotypes that respond to environmental conditions or plant physiology and cannot be obtained by other complementary approaches.

Isotopically nonstationary 13C flux analysis of changes in XXXX leaf metabolism due to high light acclimation.

@entity505 :: ('MESH:D002244', 'Chemical') :: ['carbon'] @entity958 :: ('3702', 'Species') :: ['Arabidopsis thaliana'] @entity7352 :: ('CHEBI:36928', 'Chemical') :: ['(13)C'] @entity515 :: ('CHEBI:29334', 'Chemical') :: ['CO2']
@entity958 :: (3702,Species) :: ['Arabidopsis thaliana']
