Contributions of sucrose synthase and invertase to the metabolism of sucrose in developing leaves: estimation by alternate substrate utilization

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.85.2.407· OSTI ID:5401233

Schmalstig, J G; Hitz, W D

The relative contributions of invertase and sucrose synthase to initial cleavage of phloem-imported sucrose was calculated for sink leaves of soybean (Glycine max L. Merr cv Wye) and sugar beet (Beta vulgaris L. monohybrid). Invertase from yeast hydrolyzed sucrose 4200 times faster than 1'-deoxy-1'-fluorosucrose (FS) while sucrose cleavage by sucrose synthase from developing soybean leaves proceeded only 3.6 times faster than cleavage of FS.(/sup 14/C)Sucrose and (/sup 14/C)FS, used as tracers of sucrose, were transported at identical rates to developing leaves through the phloem. The rate of label incorporation into insoluble products varied with leaf age from 3.4 to 8.0 times faster when (/sup 14/C)sucrose was supplied than when (/sup 14/C)FS was supplied. The discrimination in metabolism was related to enzymatic discriminations against FS to calculate the relative contributions of invertase and sucrose synthase to sucrose cleavage. In the youngest soybean leaves measured, 4% of final laminar length (FLL), all cleavage was by sucrose synthase. Invertase contribution to sucrose metabolism was 47% by 7.6% FLL, increased to 54% by 11% FLL, then declined to 42% for the remainder of the import phase. In sugar beet sink leaves at 30% FLL invertase contribution to sucrose metabolism was 58%.

• Research Organization: E.I. du Pont de Nemours and Company, Wilmington, DE
• OSTI ID: 5401233
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 85:2; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BEETS
CARBOHYDRATES
CARBON 14 COMPOUNDS
CLEAVAGE
CRYSTAL STRUCTURE
DISACCHARIDES
ENZYME ACTIVITY
ENZYMES
FOOD
GLYCINE HISPIDA
ISOMERASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEAVES
LEGUMINOSAE
LIGASES
METABOLISM
MICROORGANISMS
MICROSTRUCTURE
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
PLANTS
RHIZOBIUM
SACCHARIDES
SACCHAROSE
SUBSTRATES
SUGAR BEETS
TRACER TECHNIQUES
VEGETABLES