Sugar uptake and starch biosynthesis by slices of developing maize endosperm

Journal Article · Wed Oct 31 23:00:00 EST 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.94.3.996· OSTI ID:5841343

Felker, F C ^[1]; Liu, Kangchien; Shannon, J C ^[2]

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1. Department of Agriculture, Peoria, IL (USA)
2. Pennsylvania State Univ., University Park (USA)

{sup 14}C-Sugar uptake and incorporation into starch by slices of developing maize (Zea mays L.) endosperm were examined and compared with sugar uptake by maize endosperm-derived suspension cultures. Rates of sucrose, fructose, and D- and L-glucose uptake by slices were similar, whereas uptake rates for these sugars differed greatly in suspension cultures. Concentration dependence of sucrose, fructose, and D-glucose uptake was biphasic (consisting of linear plus saturable components) with suspension cultures but linear with slices. These and other differences suggest that endosperm slices are freely permeable to sugars. After diffusion into the slices, sugars were metabolized and incorporated into starch. Starch synthesis, but not sugar accumulation, was greatly reduced by 2.5 millimolar p-chloromercuribenzenesulfonic acid and 0.1 millimolar carbonyl cyanide m-chlorophenylhydrazone. Starch synthesis was dependent on kernel age and incubation temperature, but not on external pH (5 through 8). Competing sugars generally did not affect the distribution of {sup 14}C among the soluble sugars extracted from endosperm slices incubated in {sup 14}C-sugars. Competing hexoses reduced the incorporation of {sup 14}C into starch, but competing sucrose did not, suggesting that sucrose is not a necessary intermediate in starch biosynthesis. The bidirectional permeability of endosperm slices to sugars makes the characterization of sugar transport into endosperm slices impossible, however the model system is useful for experiments dealing with starch biosynthesis which occurs in the metabolically active tissue.

• OSTI ID: 5841343
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 94:3; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOSYNTHESIS
BODY
CARBOHYDRATES
CARBON 14 COMPOUNDS
CEREALS
ENDOSPERM
GRAMINEAE
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LILIOPSIDA
MAGNOLIOPHYTA
MAIZE
METABOLISM
ORGANIC COMPOUNDS
PLANT TISSUES
PLANTS
POLYSACCHARIDES
SACCHARIDES
SYNTHESIS
TISSUES
TRACER TECHNIQUES
UPTAKE