Effect of altered sink:source ratio on photosynthetic metabolism of source leaves
When seven crop species were grown under identical environmental conditions, decreased sink:source ratio led to a decreased photosynthetic rate within 1 to 3 days in Cucumis sativus L., Gossypium hirsutum L., and Raphanus sativus L., but not in Capsicum annuum L., Solanum melongena L., Phaseolus vulgaris L., or Ricinus communis L. The decrease was not associated with stomatal closure. In cotton and cucumbers, sink removal led to an increase in starch and sugar content, in glucose 6-phosphate and fructose 6-phosphate pools, and in the proportion of /sup 14/C detected in sugar phosphates and UDPglucose following /sup 14/CO/sub 2/ supply. When mannose was supplied to leaf discs to sequester cytoplasmic inorganic phosphate, promotion of starch synthesis, and inhibition of CO/sub 2/ fixation, were observed in control discs, but not in discs from treated plants. Phosphate buffer reduced starch synthesis in the latter, but not the former discs. The findings suggest that sink removal led to a decreased ratio inorganic phosphate:phosphorylated compounds. In beans /sup 14/C in sugar phosphates increased following sink removal, but without sucrose accumulation, suggesting tighter feedback control of sugar level. Starch accumulated to higher levels than in the other plants, but CO/sub 2/ fixation rate was constant for several days.
- Research Organization:
- Institute of Soils and Water Agricultural Research Organization, Dagan, Israel
- OSTI ID:
- 5600401
- Journal Information:
- Plant Physiol.; (United States), Vol. 85:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOTOSYNTHESIS
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBON DIOXIDE FIXATION
CASTOR
COTTON PLANTS
CUCUMBERS
GLUCOSE
LEAVES
PEPPERS
PHASEOLUS
PHOSPHATES
RADISHES
SOLANUM
TRACER TECHNIQUES
ALDEHYDES
BACTERIA
CARBOHYDRATES
CHEMICAL REACTIONS
FOOD
HEXOSES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEGUMINOSAE
MEDICINAL PLANTS
MICROORGANISMS
MONOSACCHARIDES
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
PLANTS
REACTION KINETICS
RHIZOBIUM
SACCHARIDES
SYNTHESIS
VEGETABLES
550501* - Metabolism- Tracer Techniques