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Photorespiration-dependent increases in phospho enolpyruvate carboxylase, isocitrate dehydrogenase and glutamate dehydrogenase in transformed tobacco plants deficient in ferredoxin-dependent glutamine-alpha-ketoglutarate aminotransferase
- Source :
- Planta, Planta, Springer Verlag, 2002, 214 (6), pp.877-886. ⟨10.1007/s00425-001-0692-2⟩
- Publication Year :
- 2002
- Publisher :
- HAL CCSD, 2002.
-
Abstract
- The metabolic cross-talk associated with re-assimilation of photorespiratory NH4+ was analysed in transformed tobacco (Nicotiana tabacum L.) plants with low activities of ferredoxin-dependent glutamine-alpha-ketoglutarate aminotransferase (Fd-GOGAT; EC 1.4.7.1). Amounts of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco; EC 4.1.1.39) protein and Rubisco transcripts were similar in all lines whether photorespiration rates were low (4,000 microl l(-1) CO2) or high (air). Leaf sucrose, hexose and starch contents were similar in all lines. In contrast, there was evidence that anaplerotic carbon flow was stimulated in the transformed lines with less than 60% Fd-GOGAT, since phospho enolpyruvate carboxylase (PEPc) activity and (PEPc) protein were increased. A strong positive correlation between leaf PEPc activity and glutamine accumulation was observed, suggesting that the increase in PEPc was related to the accumulation of glutamine. A modest stimulation of total NADP-isocitrate dehydrogenase (ICDH; EC 1.1.1.42) activity was also observed in the transformed lines with less than 60% Fd-GOGAT. This was accompanied by increases in both the cytosolic ICDH and mitochondrial NAD-isocitrate dehydrogenases (IDH; EC 1.1.1.41). IDH protein was also increased in the transformed plants with low Fd-GOGAT, suggesting that both IDH and ICDH are involved in the production of carbon skeletons (and ultimately alpha-ketoglutarate) necessary for the re-assimilation of NH4+. In contrast, PEPc, ICDH and IDH transcripts were similar in all lines. The aminating (but not the de-aminating) activity of NAD(H)-glutamate dehydrogenase (NAD(H)-GDH; EC 1.4.1.2) was greatly increased in plants with less than 60% of Fd-GOGAT after transfer to air. The data confirm that NH4+ or glutamine are involved in signalling, leading to modified gene expression and enzyme activity required for enhanced production of the C skeletons, to accommodate increases in the assimilation of photorespiratory NH4+. In addition, we provide the first demonstration of a compensatory role for NAD(H)-GDH in stabilising the leaf glutamic acid pool when Fd-GOGAT becomes limiting.
- Subjects :
- Glutamine
Ribulose-Bisphosphate Carboxylase
[SDV]Life Sciences [q-bio]
Glutamic Acid
Dehydrogenase
Plant Science
Biology
Cytosol
Oxygen Consumption
Glutamate Dehydrogenase
Tobacco
Genetics
Photosynthesis
Glutamate dehydrogenase
RuBisCO
food and beverages
Plants, Genetically Modified
Molecular biology
Carbon
Isocitrate Dehydrogenase
Phosphoenolpyruvate Carboxylase
Enzymes
Mitochondria
Plant Leaves
Quaternary Ammonium Compounds
Isocitrate dehydrogenase
Biochemistry
biology.protein
Carbohydrate Metabolism
Ketoglutaric Acids
Photorespiration
Amino Acid Oxidoreductases
NAD+ kinase
Phosphoenolpyruvate carboxylase
Signal Transduction
Subjects
Details
- Language :
- English
- ISSN :
- 00320935 and 14322048
- Database :
- OpenAIRE
- Journal :
- Planta, Planta, Springer Verlag, 2002, 214 (6), pp.877-886. ⟨10.1007/s00425-001-0692-2⟩
- Accession number :
- edsair.doi.dedup.....2bb5a31264f8af3eeb8c58067cc2e1ac