Occurrence of Natural Cytokinin in Potato Tuber

Abstract

The present investigation was undertaken to confirm the presence of the endogenous natural cytokinin (s) in the potato tubers. The methanol extract of potato tuber was separated by ascending paper chromatography using n-butanol: acetic acid: water (12:3:5) solvent system. Several violet or blue fluorescent spots on the test strip of chromatogram were detected by UV-lamp, and two of them (Rf 0.40-0.50 and Rf 0.55-0.60) not only reacted positively by Vischer's reagent but showed strikingly absorption by the UV-lamp at 260mμ. Accordingly, one (Rf 0.40-0.50)is nucleotide and the other (Rf 0.55-0.60) is a kind of the purine derivatives. While the addition of the former fraction to the medium exerted no significant influence on the tobacco callus growth, a marked stimulation of its growth was observed due to the latter fraction. As to the effect of the fraction (Rf 0.55-0.60) on the potato tissue culture, this factor not only resulted in likewise stimulation of callus growth but enchanced to elicit the root formation at its relative high concentration. Consequently, this factor closely resembles kinetin in its cytokinin activity. It was also ascertained a considerable cytokinin activity in this factor by means of the chlorophyll-retention assay using the barley leaf section. These results are interpreted to indicate, therefore, that there is a endogenous natural cytokinin in the potato tubers.