BATCH ANION-EXCHANGE SEPARATION AND QUANTIFICATION OF [C-14] HEXOSE FROM [C-14] SUCROSE

Techniques quantifying [C-14]photoassimilate partitioning between hexose and sucrose can identify developmental and regulatory changes in sugar metabolism of sorghum (Sorghum bicolor (L.) Moench]. The objective of this study was to develop a laboratory method for separating and quantifying [C-14]hexose and [C-14]sucrose in numerous plant organ extracts simultaneously. The described method combines easily with available assays for [C-14]starch and [C-14]Structural components and for total fructose, glucose, sucrose, and starch. Treatment with hexokinase is followed by batch treatment with anion exchange resin. Hexose, as hexose phosphate, binds (> 95%) to the resin, and sucrose remains unbound (> 95%). Radiolabel in extracts is nearly completely recovered (99%). Determinations are reproducible (SE = 1.3%). This method was applied to identify differences in sugar metabolism between organs and among growth stages of field-grown sorghum.