Effect of phlorizin on sugar uptake by broadbean leaf discs. [Vica faba L]
Phlorizin is a competitive inhibitor of Na/sup +//glucose symport in animal cells and of H/sup +//3-O-methylglucose (3-O-MeG) symport in liverworts. The effects of this compound on the uptake of (U-/sup 14/C) sucrose and of (/sup 14/C) 3-O-MeG by broadbean (Vicia faba L.) leaf discs were studied. Leaf discs without lower epidermis were preincubated in the dark for 30 min (fresh discs) or for 12 h (aged discs) on a medium buffered at pH 5.0 containing mannitol as an osmoticum. They were then incubated for 30 min in the light on a similar solution added with 1 mM (/sup 14/C) sucrose or (/sup 14/C) 3-O-MeG and 5 mM phlorizin. Phlorizin inhibited uptake of 3-O-MeG by 37 and 50% respectively in fresh and aged discs. Sucrose uptake was more sensitive to the inhibitor than 3-O-MeG uptake and was also more inhibited in aged than in fresh discs (76% inhibition vs 54%). Kinetic studies showed that the inhibition exerted by phlorizin in fresh material is of competitive type both for sucrose and for 3-O-MeG uptake. Electrophysiological measurements indicated that the inhibitor did not affect the transmembrane potential difference of parenchyma cells within 30 min. The data suggest that phlorizin can be recognized by the hexose and by the sucrose carrier of leaf cells.
- Research Organization:
- CNRS, Poitiers, France
- OSTI ID:
- 5202197
- 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
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL EFFECTS
CARBOHYDRATES
DISACCHARIDES
GLYCOSIDES
KETONES
LEAVES
LEGUMINOSAE
MICROORGANISMS
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
PHASEOLUS
PHLORIZIN
PLANTS
RHIZOBIUM
SACCHARIDES
SACCHAROSE
UPTAKE