Biosynthesis of sucrose and mannitol as a function of leaf age in celery (Apium graveolens L. )

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.86.1.129· OSTI ID:7164423

Davis, J M; Fellman, J K; Loescher, W H

In celery (Apium graveolens L.), the two major translocated carbohydrates are sucrose and the acyclic polyol mannitol. Their metabolism, however, is different and their specific functions are uncertain. To compare their roles in carbon partitioning and sink-source transitions, developmental changes in /sup 14/CO/sub 2/ labeling, pool sizes, and key enzyme activities in leaf tissues were examined. The proportion of label in mannitol increased dramatically with leaf maturation whereas that in sucrose remained fairly constant. Mannitol content, however, was high in all leaves and sucrose content increased as leaves developed. Activities of mannose-6-P reductase, cytoplasmic and chloroplastic fructose-1,6-bis-phosphatases, sucrose phosphate synthase, and sucrose synthase increased with leaf maturation and decreased as leaves senesced. Ribulose bisphosphate carboxylase and nonreversible glyceraldehyde-3-P dehydrogenase activities rose as leaves developed but did not decrease. Thus, sucrose is produced in all photosynthetically active leaves whereas mannitol is synthesized primarily in mature leaves and stored in all leaves. Onset of sucrose export in celery may result from sucrose accumulation in expanding leaves, but mannitol export is clearly unrelated to mannitol concentration. Mannitol export, however, appears to coincide with increased mannitol biosynthesis. Although mannitol and sucrose arise from a common precursor in celery, subsequent metabolism and transport must be regulated separately.

• Research Organization: Washington State Univ., Pullman (USA)
• OSTI ID: 7164423
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 86:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AGE DEPENDENCE
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CARBOHYDRATES
CARBON 14 COMPOUNDS
CARBON-CARBON LYASES
CARBOXY-LYASES
CARBOXYLASE
DISACCHARIDES
ENZYME ACTIVITY
ENZYMES
ESTERASES
FOOD
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEAVES
LYASES
METABOLISM
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PHOSPHATASES
PLANTS
PRECURSOR
REACTION KINETICS
SACCHARIDES
SACCHAROSE
SYNTHESIS
TRACER TECHNIQUES
VEGETABLES