Methods to determine photorespiratory metabolic pools to improve plant productivity
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Photorespiration can limit growth of C3 plants especially under stressful conditions. Current models for future climate change predict hotter and dryer conditions in many areas, which would significantly increase photorespiration and subsequently affect crop production. Modification and engineering of photorespiration is thereby one current approach to compensate the loss of crop production affected by climate change. In this study, we employed two main strategies to better understand the dynamics of photorespiration. A counter-dogmatic accumulation of photorespiratory metabolites was identified in an Arabidopsis thaliana gox1 photorespiratory mutant therefore challenging our current understanding of the photorespiratory pathway. Here, a novel method combining protoplasts fractionation, Solid Phase Extraction and GC-MS techniques was developed to identify the sub-cellular compartmentation of these metabolites. The second strategy was detecting metabolic changes in the grass Alloteropsis semialata, which occurs as C3-, C4-, and C3-C4–intermediate (so-called C2) genotypes, using NMR-detected deuterium isotope fractionation. By exploiting the advantage that isotopomers (intramolecular isotope distributions) are a fingerprint of the regulation of photosynthetic and photorespiratory C metabolism, the deuterium isotopomer patterns of glucose derived from the genotypes allowed us to test for metabolic shifts among the genotypes. The comparison showed that there is no significant difference in isotopomer pattern among A. semialata subspecies i.e. C3, C4 and C3-C4 genotypes. These results suggest that the Calvin cycle operates with the same enzyme regulation in all genotypes. This surprising conclusion may be compatible with several previous observations, if one assumes that the C4 photosynthesis if only partly functional in the C4 genotypes. Altogether, this study contributes both technically and theoretically to better understand the dynamic of photorespiration.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:umu:diva-111071OAI: oai:DiVA.org:umu-111071DiVA: diva2:871783
Keech, Olivier, Forskarassistent
Bako, Laszlo, Univ.Lektor