Evidence for the presence of a sucrose carrier in immature sugar beet tap roots. [Beta vulgaris L]

Journal Article · Mon Feb 01 00:00:00 EST 1988 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.86.2.575· OSTI ID:7066264

Lemoine, R; Daie, J; Wyse, R ^[1]

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1. Rutgers Univ., New Brunswick, NJ (USA)

The objectives of this work were to determine the path of phloem unloading and if a sucrose carrier was present in young sugar beet (Beta vulgaris L.) taproots. The approach was to exploit the characteristics of the sucrose analog, 1{prime}-fluorosucrose (F-sucrose) which is a poor substrate for acid invertase but is a substrate for sucrose synthase. Ten millimolar each of ({sup 3}H) sucrose and ({sup 14}C)F-sucrose were applied in a 1:1 ratio to an abraded region of an attached leaf for 6 hours. ({sup 14}C)F-sucrose was translocated and accumulated in the roots at a higher rate than ({sup 3}H)sucrose. This was due to ({sup 3}H)sucrose hydrolysis along the translocation path. Presence of ({sup 3}H)hexose and ({sup 14}C)F-sucrose in the root apoplast suggested apoplastic sucrose unloading with its subsequent hydrolysis. Labeled F-sucrose uptake by root tissue discs exhibited biphasic kinetics and was inhibited by unlabeled sucrose, indicating that immature roots have the ability for carrier-mediated sucrose transport from the apoplast. Collectively, in vivo and in vitro data indicate that despite sucrose hydrolysis by the wall-bound invertase, sucrose hydrolysis is not entirely essential for sugar accumulation in this tissue.

• OSTI ID: 7066264
• Journal Information: Plant Physiology; (USA), Vol. 86:2; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
SACCHAROSE
BIOCHEMICAL REACTION KINETICS
TRANSLOCATION
AGE DEPENDENCE
CARBON 14 COMPOUNDS
ENZYME ACTIVITY
HYDROLYSIS
INHIBITION
LEAVES
ROOTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
DISACCHARIDES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LYSIS
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
REACTION KINETICS
SACCHARIDES
SOLVOLYSIS
551001* - Physiological Systems- Tracer Techniques