Potato Tuber-Inducing Activity of the Extracts of Some Root and Tuber Crops

Abstract

Potato tuber-inducing activities in the extracts of nine species of plants which formed underground storage organ were compared by tissue culture system of single-node segments of potato stems in vitro. Among the extracts from lop organs of the plants, the potato tuber-inducing activities were found in aqueous fraction from sweet potato (Ipomoea batatas) and in add ethyl acetate (AE) fractions from sweet potato, Jerusalem artichoke (Helianthus tuberosus), yacon (Polymnia sonchifolia), cassava (Manihot esculenta) and field horsetail (Equisetum arvense). The active substance in AE fraction from sweet potato was purified by HPLC and identified as jasmonic acid by El mass spectrometry. The activity in AE fraction of field horsetail seemed to relate with abscisic acid by purification using HPLC. The extracts from top organs of purple arrowroot (Canna edulis), taro (Colocasia esculenta), elephant foot (Amorphallus konjac) and sweet potato-related wild species which formed no tuberous root (Ipomoea trifida) showed no or low activities. The activity of AE fraction from tubers of Jerusalem artichoke was very high. The high activities were also found in AE fractions from stolon of Jerusalem artichoke, tuber and tuberous root of yacon and tuberous root of sweet potato and cassava. The extracts from thickening stem of purple arrowroot, tuber of taro, corm and cormlet of elephant foot showed no or low activities. From the above results, these plants were categorized from the point of view in the similarity in physiological mechanism of formation of underground storage organ with that of potato. Tuber crops in which tubers are formed after cessation of stem growth seem to have similar mechanism of tuber formation with potato. Some root crops also have some similarities. On the other hand, the similarities with potato seem to be low in tuber crops in which tubers thicken from the base of stem. © 1992, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.