Involvement of Polyamines with Adventitious Root Development in Stem Cuttings of Mung Bean

Spermine enhances the number of adventitious roots developing on stem cuttings of Phaseolus aureus</it> Roxb. This effect is observed when spermine is supplied alone to cuttings or in the presence of indolebutyric acid (IBA). That concentration most effective in inducing the rooting response also enhances root growth. Other concentrations tested were without effect on growth. Spermidine does not influence root number or growth except at high concentration, when it is inhibitory to number only. Methylglyoxal bis(guanylhydrazone) (MGBG) inhibits rooting and root growth in the presence or absence of IBA. Treatment of stem-cuttings with IBA leads to enhanced levels of spermine, spermidine and putrescine in the hypocotyl prior to development of any root primordia. MGBG reduces the levels of spermine and spermidine whilst increasing the level of putrescine. Furthermore, MGBG prevents the IBA-induced increase in spermine and markedly inhibits that in spermidine. These results are consistent with an essential role for polyamines and their metabolism in the early events which lead to adventitious root development.