Characterisation of potato leaf starch with iodine-staining

The structure of starch from potato leaves collected early morning and late afternoon in the middle of July was studied. Starch was extracted from the leaves with dimethylsulphoxide and purified in several steps. Sepharose CL-2B elution profiles of the starches detected by iodine-staining showed that amylopectin from the leaf starches had broader size ranges than tuber starch amylopectin. Additionally, in leaf starch there was an increase during the day in the proportion of a fraction that had a similar size range to amylopectin from tuber starch. Amylopectins in both leaf and tuber starches were found to have similar average chain length, while amyloses showed different spectra with iodine-staining. Potato leaf and tuber starches seemed to be composed only of amylose and amylopectin with similar chain length distribution over their molecular weight ranges.