Regulation of starch synthesis in potato tubers
- Scottish Crop Res. Inst., Dundee (Scotland)
Following tuber excision from the mother plant sucrose synthase activity fell from 3,120 to 960 nmol/g.f. wt./h within 7 days and starch synthesis ({sup 14}C sucrose incorporated into isolated discs) from 23 to 7 nmol/g.f. wt./h. While the maximum catalytic activity of sucrose synthase was more than sufficient to account for the observed rate of starch synthesis a maximum of 27% of sucrose incorporated by discs was converted into starch within 3 h. This compared with 80% conversion of {sup 14}C glucose incorporated. Tuber excision also reduced the rate of starch biosynthesis with glucose as a substrate (from 206 to 64 nmol/g.f. wt./h). The activities of UDPG-pyrophosphorylase, PPi-PFK, ATP-PFK, starch synthase and hexokinase (glucose or fructose substrates) were unaffected by tuber removal. ADPG pyrophosphorylase activity was reduced from 8,000 to 4,500 nmol/g.f. wt./h. Preliminary experiments indicate that the decline in sucrose synthease activity is prevented by maintaining sucrose flux into tubers through the cut stolon.
- OSTI ID:
- 5627808
- Report Number(s):
- CONF-9007196-; CODEN: PPYSA
- Journal Information:
- Plant Physiology, Supplement; (USA), Vol. 93:1; Conference: Annual meeting of the American Society of Plant Physiologists, Indianapolis, IN (USA), 29 Jul - 2 Aug 1990; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ENZYME ACTIVITY
BIOLOGICAL PATHWAYS
STARCH
BIOSYNTHESIS
CARBON 14 COMPOUNDS
POTATOES
PYROPHOSPHATES
SACCHAROSE
TRACER TECHNIQUES
CARBOHYDRATES
DISACCHARIDES
FOOD
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PLANTS
POLYSACCHARIDES
REAGENTS
SACCHARIDES
SYNTHESIS
TUBERS
VEGETABLES
550501* - Metabolism- Tracer Techniques