A simple and rapid method for the analysis of water soluble carbohydrates from small segments of cereal leaf tissue

A simple three-step assay has been developed for the analysis of nanomole quantities of glucose, fructose and sucrose from small plant samples in the presence of fructans. The assay of crude ethanol/water extracts proceeds by the sequential addition of the commercially available enzymes; hexokinase, phosphogluco-isomerase, and sucrose Phosphorylase. The assay was compared with conventional coupled assays for glucose and fructose, together with TLC and HPLC assays for total water-soluble carbohydrates. All assays showed similar results over the range of standards and plant samples tested. The assay has been developed for use on microtiter plate readers, allowing for the screening of large numbers of samples rapidly. Fructan content in the same plant samples can be calculated following the determination of total free and combined hexoses.