Influence of starch deficiency on photosynthetic and post-photosynthetic carbon isotope fractionations
Abstract
Carbon isotope (^13C) fractionations occurring during and after photosynthetic CO_2 fixation shape the carbon isotope composition (δ^13C) of plant material and respired CO_2. However, responses of ^13C fractionations to diel variation in starch metabolism in the leaf are not fully understood. Here we measured δ^13C of organic matter (δ^13COM), concentrations and δ^13C of potential respiratory substrates, δ^13C of dark-respired CO_2 (δ^13CR), and gas exchange in leaves of starch-deficient plastidial phosphoglucomutase (pgm) mutants and wild-type plants of four species (Arabidopsis thaliana, Mesembryanthemum crystallinum, Nicotiana sylvestris, and Pisum sativum). The strongest δ^13C response to the pgm-induced starch deficiency was observed in N. sylvestris, with more negative δ^13COM, δ^13CR, and δ^13C values for assimilates (i.e. sugars and starch) and organic acids (i.e. malate and citrate) in pgm mutants than in wild-type plants during a diel cycle. The genotype differences in δ^13C values could be largely explained by differences in leaf gas exchange. In contrast, the PGM-knockout effect on post-photosynthetic ^13C fractionations via the plastidic fructose-1,6-bisphosphate aldolase reaction or during respiration was small. Taken together, our results show that the δ^13C variations in starch-deficient mutants are primarily explained by photosynthetic ^13C fractionations and that the combination of knockout mutants and isotope analyses allows additional insights into plant metabolism. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000338761Publication status
publishedExternal links
Journal / series
Journal of Experimental BotanyVolume
Pages / Article No.
Publisher
Oxford University PressSubject
Assimilates; Carbon allocation; Carbon storage; Ecophysiology; Isotope effect; Metabolic fluxes; Non-structural carbohydrates (NSCs); Plant respiration; Starch-deficient mutant (SDM); Starchless mutantOrganisational unit
03648 - Buchmann, Nina / Buchmann, Nina
Funding
132768 - Carbon isotope fractionation during respiration: Mechanisms and environmental drivers (SNF)
153545 - Carbon isotope fractionation during leaf and root respiration as a function of nitrogen nutrition (SNF)
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