| Abstract: | Phillips, R., Press, M. C. and Eason, A. 1987. Polyamines inrelation to cell division and xylogenesis in cultured explantsof Helianthus tuberosus: lack of evidence for growth-regulatoryaction.—J. exp. Bot. 38: 164–172. The polyamines spermidine, diaminopropane, and cadaverine werefound to accumulate in cultured tuber explants of H. tuberosus(Jerusalem artichoke). Rapid increases in all amines occurredduring the initial 24 h corresponding to the period of activationand the onset of mitosis. Levels then declined during the followingphases of rapid cell proliferation and xylem differentiation.The type and distribution of polyamines was not markedly affectedby changes in medium or culture conditions, and the inhibitorMGBG did not alter cell division rates or polyamine contentmarkedly although xylem differentiation was substantially depressed.Exogenously supplied spermidine and putrescine did not substantiallyalter the cellular responses of explants cultured in the presenceof auxin. In the absence of supplied auxin, spermidine at 1?0mol m–3 produced an increase in cell division, althoughthis was small in comparison with auxin-stimulated responses.The implications of these findings on the possibility that polyaminesact as growth regulators in plants is discussed. Key words: Polyamines, Jerusalem artichoke, cultured explants, cell division, xylem differentiation |
