Transformation and Translocation of Photoassimilated ^<13>CO_2 and Glycine-2-^<13>C in Sunflower Leaves Detected by ^<13>C-NMR

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概要

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• The intact leave of sunflower (Helianthus annuus L. cv. Russian Mammoth) plants were fed with ^<13>CO_2 and the glycine-2-^<13>C and incorporation of the ^<13>C label into various compounds was examined by ^<13>C unclear magnetic resonance (NMR) using an ethanol-water soluble extract of the leaves and intact petiole segments. Most of the photoassimilated CO_2 were converted into sugars such as glucose, fructose, and sucrose. Their peak intensities in the ^<13>C-NMR spectra increased linearly with time up to 30 min after the start of feeding. Considerable labeling which occurred also in glycine, serine, and alanine within 10 min remained constant thereafter. The ^<13>c label in glycine-2 was first transferred to serine-2 and -3. The carboxyl carbons of glycine and serine were concomitantly labeled with ^<13>C. Glucose an sucrose also became labeled after a 60 min lag period. These results suggest that a part of the photoassimilated CO_2 was metabolized through the glycolate pathway and that glycine applied exogenously to the leaves was converted to serine whose metabolites may enter the Calvin cycle and be utilized as substrates for sugar synthesis and the glycolate pathway. Consequently, carboxyl labeled glycine and serine may be produced. The content of ammonia hardly changed while that of glutamine and aspartate increased remarkably, indicating that ammonia formed by glycine condensation was efficiently assimilated to glutamine and aspartate. Sucrose was the only substance labeled with ^<13>C in the petioles upon the application of ^<13>CO_2 to the leaves. A small peak corresponding to serine-2 was observed in the case of glycine-2-^<13>C feeding. It is suggested that although in sunflower plants photoassimilates are mainly exported in the form of sucrose, serine may play some role in the translocation. The application of ^<13>C-NMR has been found to be a suitable analytical method for ^<13>C tracer experiments to investigate the metabolism and translocation of carbon compounds in plants.

• 一般社団法人日本土壌肥料学会の論文

著者

• Ito Osamu

  National institute of Agro-Environmental Sciences

• Mitsumori Fumiyuki

  National Institute For Environmental Studies

• Ito Osamu

  National Institute For Environmental Studies

関連論文

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• Transformation and Translocation of Photoassimilated ^CO_2 and Glycine-2-^C in Sunflower Leaves Detected by ^C-NMR

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