Transformation and translocation of photoassimilated13CO2and glycine-2-13C in sunflower leaves detected by13C-NMR

Ito, Osamu; Mitsumori, Fumiyuki

doi:10.1080/00380768.1992.10416499

Cited by 8 publications

(6 citation statements)

References 19 publications

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“…Even after the long chase period of 24 h sucrose was the only labelled sugar detected in the petiole of the 13 CO 2 ‐treated leaf (Table 6). So far, the results are in accordance with data reported by Ito & Mitsumori (1992) who concluded from 13 C‐NMR analyses that sucrose is the main transport sugar in the sunflower phloem. However, the sunflower extracts additionally contained raffinose and myo ‐inositol (Table 5), which are further candidates for phloem transport.…”

Section: Discussionmentioning

confidence: 99%

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Evidence for sectorial photoassimilate supply in the capitulum of sunflower (Helianthus annuus)

2002

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Summary• Photoassimilate transport from source leaves to the capitulum was investigated in sunflower ( Helianthus annuus ) during anthesis and seed filling.• Following foliar application of a 13/14 CO 2 -pulse, labelled photoassimilates were detected using mass spectrometry, phosphorimaging, HPTLC and HPLC.• The upper 10 (to 15) leaves exported photoassimilates into the capitulum. Photoassimilate distribution patterns were sectorial: each leaf supplied a defined 2/8 -3/8 sector of the capitulum. Photoassimilates exported via the midvein accumulated in a 1/8 sector, which aligned exactly with the insertion site of the leaf. The two main lateral veins of the leaf exported photoassimilates into the two adjacent 1/8 sectors of the capitulum. During early and late stages of anthesis, strong sinks were staminate florets and young achenes, respectively. During seed filling, an import maximum and minimum appeared in the intermediate and central whorls, respectively. Sucrose was established as the only phloem transport sugar. Raffinose, although also 14 C-labelled in the path, is not transported in sunflower.• It is concluded that a single floret is typically connected with the leaves of three neighbouring ortostichies in sunflower. Photoassimilate distribution patterns demonstrated here generally may reflect the functional relationships between the phyllotaxy of source leaves and the position of sinks in developing inflorescences like those of Asteraceae.

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Section: Discussionmentioning

confidence: 99%

“…Sucrose is evidently the main transport sugar (e.g. Ito & Mitsumori, 1992). However, in the present study raffinose and myo ‐inositol were also found in petiole and stem.…”

Section: Introductionmentioning

confidence: 99%

Evidence for sectorial photoassimilate supply in the capitulum of sunflower (Helianthus annuus)

2002

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“…In one approach the metabolic fate of the amino nitrogen is followed by 15 N-labelling and 15 N NMR (Neeman et al 1985;Hartung and Ratcliffe 2002); while in a second approach the metabolism of the carbon skeleton is followed using 13 C-labelling and 13 C NMR (Ashworth and Mettler 1984;Neeman et al 1985;Ito and Mitsumori 1992;Prabhu et al 1996bPrabhu et al , 1998Mouillon et al 1999;Hartung and Ratcliffe 2002). The 13 C NMR analysis of [2-13 C] glycine metabolism is particularly informative, because of the characteristic spectroscopic signature that arises from the catalytic activity of the glycine decarboxylase (GDC)/serine hydroxymethyltransferase (SHMT) system.…”

Section: Amino Acid Metabolismmentioning

confidence: 99%

NMR analysis of plant nitrogen metabolism

Mesnard¹,

Ratcliffe

2005

Photosynth Res

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The analysis of primary and secondary nitrogen metabolism in plants by nuclear magnetic resonance (NMR) spectroscopy is comprehensively reviewed. NMR is a versatile analytical tool, and the combined use of (1)H, (2)H, (13)C, (14)N and (15)N NMR allows detailed investigation of the acquisition, assimilation and metabolism of nitrogen. The analysis of tissue extracts can be complemented by the in vivo NMR analysis of functioning tissues and cell suspensions, and by the application of solid state NMR techniques. Moreover stable isotope labelling with (2)H-, (13)C- and (15)N-labelled precursors provides direct insight into specific pathways, with the option of both time-course and steady state analysis increasing the potential value of the approach. The scope of the NMR method, and its contribution to studies of plant nitrogen metabolism, are illustrated with a wide range of examples. These include studies of the GS/GOGAT pathway of ammonium assimilation, investigations of the metabolism of glutamate, glycine and other amino acids, and applications to tropane alkaloid metabolism. The continuing development of the NMR technique, together with potential applications in the emerging fields of metabolomics and metabolic flux analysis, leads to the conclusion that NMR will play an increasingly valuable role in the analysis of plant nitrogen metabolism.

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“…In the past years, metabolic fluxes in the TCA pathway and/or Glu production have been examined using isotopic tracing, either using 13 CO 2 (Ito & Mitsumori, ; Tcherkez et al ., ; Gauthier et al ., ; Szecowka et al ., ) or 13 C‐labelled substrates (Tcherkez et al ., , ). Glu neosynthesis from current photosynthetic 13 C represents a minor 13 C‐sink (Szecowka et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Direct assessment of the metabolic origin of carbon atoms in glutamate from illuminated leaves using ¹³C‐NMR

et al. 2017

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Summary Glutamate (Glu) is the cornerstone of nitrogen assimilation and photorespiration in illuminated leaves. Despite this crucial role, our knowledge of the flux to Glu de novo synthesis is rather limited. Here, we used isotopic labelling with 13CO2 and 13C‐NMR analyses to examine the labelling pattern and the appearance of multi‐labelled species of Glu molecules to trace the origin of C‐atoms found in Glu. We also compared this with 13C‐labelling patterns in Ala and Asp, which reflect citrate (and thus Glu) precursors, that is, pyruvate and oxaloacetate. Glu appeared to be less 13C‐labelled than Asp and Ala, showing that the Glu pool was mostly formed by ‘old’ carbon atoms. There were modest differences in intramolecular 13C–13C couplings between Glu C‐2 and Asp C‐3, showing that oxaloacetate metabolism to Glu biosynthesis did not involve C‐atom redistribution by the Krebs cycle. The apparent carbon allocation increased with carbon net photosynthesis. However, when expressed relative to CO2 fixation, it was clearly higher at low CO2 while it did not change in 2% O2, as compared to standard conditions. We conclude that Glu production from current photosynthetic carbon represents a small flux that is controlled by the gaseous environment, typically upregulated at low CO2.

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Transformation and translocation of photoassimilated¹³CO₂and glycine-2-¹³C in sunflower leaves detected by¹³C-NMR

Cited by 8 publications

References 19 publications

Evidence for sectorial photoassimilate supply in the capitulum of sunflower (Helianthus annuus)

Evidence for sectorial photoassimilate supply in the capitulum of sunflower (Helianthus annuus)

NMR analysis of plant nitrogen metabolism

Direct assessment of the metabolic origin of carbon atoms in glutamate from illuminated leaves using ¹³C‐NMR

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Transformation and translocation of photoassimilated13CO2and glycine-2-13C in sunflower leaves detected by13C-NMR

Cited by 8 publications

References 19 publications

Evidence for sectorial photoassimilate supply in the capitulum of sunflower (Helianthus annuus)

Evidence for sectorial photoassimilate supply in the capitulum of sunflower (Helianthus annuus)

NMR analysis of plant nitrogen metabolism

Direct assessment of the metabolic origin of carbon atoms in glutamate from illuminated leaves using 13C‐NMR

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Transformation and translocation of photoassimilated¹³CO₂and glycine-2-¹³C in sunflower leaves detected by¹³C-NMR

Direct assessment of the metabolic origin of carbon atoms in glutamate from illuminated leaves using ¹³C‐NMR