| Abstract: | Plantlets of Solanum tuberosum L. cv. Sirtema were used to studythe regulation of the long-distance transport of potassium.The effects of polyamines and two plant hormones, abscisic acid(ABA) and benzyladenine (BA), on this process were investigated.Foliar sprays of putrescine or BA increased the transport of(K) 86Rb to the upper part of the plant. In contrast, spermidinetreatment enhanced the translocation into the growing tuber,as did ABA. These specific effects were partially correlatedto the distribution of endogenous polyamines within the plant.Spermidine was the predominant polyamine in the tuber whileputrescine was as abundant as spermidine in the leaves. Thetotal amount of putrescine, spermidine and spermine decreasedwith the physiological age of the leaves and tubers. Moreover,from heat-girdling experiments, it was shown that the polyamine,14C-putrescine, supplied to a leaf, was transported via thephloem. It is suggested that polyamines like phytohormones havea regulatory role in long-distance transport. Key words: Hormone-directed-transport, K, phloem, polyamines, potato, 14C-putrescine transport |
