Phloem unloading in tomato fruit
To begin to identify those processes that contribute to the regulation of photosynthate partitioning in tomato fruit the path of phloem unloading in this tissue has been characterized. Assymetrically labelled sucrose (/sup 3/H-fructosyl sucrose) was applied to source leaves. Following translocation to the fruit the apoplast was sampled. The appearance of assymetric sucrose and /sup 3/H-fructose in the apoplast indicates that phloem unloading is apoplastic and that extracellular invertase is active. Estimation of sucrose, glucose, and fructose concentrations in the apoplast were 1 mM, 40 mM, and 40 mM, respectively. Rates of uptake of sucrose, 1-fluorosucrose, glucose, and fructose across the plasma membrane were similar and non-saturating at physiological concentrations. These results suggest that, although extracellular invertase is present, sucrose hydrolysis is not required for uptake into tomato fruit pericarp cells. 1-fluorosucrose is used to investigate the role of sucrose synthase in hydrolysis of imported photosynthate.
- Research Organization:
- Univ. of California, Davis
- OSTI ID:
- 5121578
- Journal Information:
- Plant Physiol., Suppl.; (United States), Journal Name: Plant Physiol., Suppl.; (United States) Vol. 80:4; ISSN PPYSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL PATHWAYS
CARBOHYDRATES
CELL CONSTITUENTS
CELL WALL
DISACCHARIDES
FOOD
FRUITS
HYDROGEN ISOTOPES
ISOTOPES
LABELLING
LEAVES
LIGHT NUCLEI
NUCLEI
ODD-EVEN NUCLEI
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
RADIOISOTOPES
RADIONUCLIDE KINETICS
SACCHARIDES
SACCHAROSE
TOMATOES
TRANSLOCATION
TRITIUM
UPTAKE
YEARS LIVING RADIOISOTOPES