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Tracking sulfur and phosphorus within single starch granules using synchrotron X-ray microfluorescence mapping
Alain Buléon1, Marine Cotte, Jean-Luc Putaux
1INRA-UR 1268 BIA, Rue de la Géraudière, BP 71627, F-44316 Nantes cedex 3, France.
Biochimica Et Biophysica Acta
|September 11, 2013
Summary
Synchrotron micro-X-ray fluorescence (μXRF) imaging reveals the distribution of granule-bound starch synthase 1 (GBSS1) and phosphate groups in starch granules. This technique helps understand starch biosynthesis and structure by analyzing minor constituents in different genetic backgrounds.
Area of Science:
- Plant biochemistry and molecular biology
- Carbohydrate chemistry
- Analytical chemistry
Background:
- Native starch granules contain amylose, amylopectin, phosphate, and proteins.
- Granule-bound starch synthase 1 (GBSS1) is crucial for amylose biosynthesis.
- Phosphate groups play a significant role in starch metabolism.
Purpose of the Study:
- To apply synchrotron micro-X-ray fluorescence (μXRF) for high-resolution mapping of GBSS1 and phosphate groups in starch.
- To investigate the distribution of these components in wild-type and mutant starches.
- To elucidate the role of GBSS1 and phosphorylation in starch structure and biosynthesis.
Main Methods:
- Utilized synchrotron micro-X-ray fluorescence (μXRF) for elemental mapping.
- Analyzed sulfur (S) XRF signal for GBSS1 and phosphorus (P) XRF signal for phosphate groups.
- Studied wild-type potato and maize starches, alongside mutants lacking GBSS1 or starch-phosphorylating enzymes.
Main Results:
- Wild-type starches showed higher phosphorylation and sulfur content compared to mutants.
- Phosphate groups were primarily located at the periphery of wild-type potato starch granules.
- In amylose-free mutants, phosphate groups were distributed throughout the granule.
Conclusions:
- μXRF imaging successfully visualized GBSS1 (via S mapping) and phosphate distribution in starch.
- Antisense suppression of GBSS1 expression was confirmed by S mapping in potato starch.
- P mapping supported the hypothesis that amylose is centrally located within starch granules.
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