Fructosyl Transfer between 1-Kestose and Sucrose in Wheat Leaves

Area of Science:

• Carbohydrate Chemistry
• Plant Biochemistry
• Metabolic Pathway Analysis

Background:

• 1-kestose is a trisaccharide composed of two fructosyl units and one glucosyl unit.
• Understanding sugar moiety labeling is crucial for elucidating plant metabolic pathways.

Purpose of the Study:

• To investigate the differential labeling patterns of 1-kestose sugar moieties using in vivo and in vitro methods.
• To determine the cause of uneven specific radioactivity observed in vivo.

Main Methods:

• In vivo pulse labeling of plants with carbon-14 dioxide ((14)CO(2)).
• In vitro labeling of 1-kestose with carbon-14 sucrose ((14)C-sucrose).
• Measurement of specific radioactivities of the internal and terminal fructosyl moieties of 1-kestose.

Main Results:

• In vivo labeling with (14)CO(2) resulted in significantly lower specific radioactivity in the terminal fructosyl moiety of 1-kestose compared to the internal moiety.
• In vitro labeling with (14)C-sucrose showed similar specific radioactivities for both fructosyl moieties.
• Enzymatic transfer of the terminal fructosyl residue from 1-kestose to sucrose was identified as the cause of the observed in vivo labeling pattern.

Conclusions:

• The metabolic fate of 1-kestose in plants differs significantly between in vivo and in vitro conditions.
• Enzymatic transglycosylation plays a key role in the distribution of radioactivity within 1-kestose during plant metabolism.
• This study provides insights into the dynamic nature of carbohydrate metabolism in plants.