Evidence of multiple sugar uptake across the plasma membrane of laticifer protoplasts from Hevea.
In Hevea, rubber synthesis is confined to the cytosol of the highly differentiated laticifer cells. Agronomic and biochemical studies showed that this process uses high amounts of sugars that are efficiently imported into the laticifer. A H(+)-sugar symport system located in the plasma membrane is involved in sugar uptake into laticifers. Laticifer protoplasts were prepared and used in electrophysiological and labeling experiments to test the capacity of this system to transport a variety of sugars such as oligosaccharides from the raffinose family, trace compounds in rubber. Translocation of sugars known to be transported with different efficiency across the plasma membrane of plant cells was also tested. A 1 mM sucrose affinity was found for the symport. All the sugars tested, except palatinose induce membrane depolarization indicating that they were actively absorbed by the laticifer network. This reveals the wide capacity of this peculiar sink for the uptake of sugars.
Bouteau
F
F
Université Paris 7, France. bouteau@moka.ccr.jussieu.fr
Dellis
O
O
Bousquet
U
U
Rona
J P
JP
D050260:Carbohydrate Metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004594:Electrophysiology; D019665:Euphorbiaceae / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007840:Latex / Q000378:metabolism*; D008839:Microelectrodes; D018408:Patch-Clamp Techniques; D011523:Protoplasts / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
D007840:Latex; D013395:Sucrose; D005947:Glucose