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

Techniques quantifying [C-14]photoassimilate partitioning between hexo se and sucrose can identify developmental and regulatory changes in su gar metabolism of sorghum (Sorghum bicolor (L.) Moench]. The objective of this study was to develop a laboratory method for separating and q uantifying [C-14]hexose and [C-14]sucrose in numerous plant organ extr acts simultaneously. The described method combines easily with availab le assays for [C-14]starch and [C-14]Structural components and for tot al fructose, glucose, sucrose, and starch. Treatment with hexokinase i s followed by batch treatment with anion exchange resin. Hexose, as he xose phosphate, binds (> 95%) to the resin, and sucrose remains unboun d (> 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.