The role of indole-3-butyric acid and polyamines on in vitro rooting of microshoots of Rosa damascena Mill. and Gladiolus hybridus Hort.

Abstract

The effect of indole-3-butyric (IBA) acid and polyamines was investigated on in vitro rooting of microshoots of Rosa damascena Mill. (difficult-to-root) and Gladiolus hybridus Hort. (easy-to-root) plants. Both IBA and putrescine (PUT) individually induced rooting and showed a synergistic effect in the rooting of microshoots of both plant species. Maximum rooting of microshoots (%) was observed on Murashige and Skoog medium (MS medium) supplemented with 2.5 μM IBA and 100 μM PUT. The incorporation of methylglyoxal(bis) guanylhydrazone (MGBG: a competitive inhibitor of s-adenosyl methionine decarboxylase and is known to block spermidine and spermine synthesis) completely inhibited the rooting of microshoots of both plant species. Similarly, the incorporation of l-aminoguanidine (AG: an inhibitor of diamine oxidase) also inhibited the adventitious rooting of microshoots of both species, indicating the role of the oxidation product of PUT in rooting. Rooting was not observed in either species when a medium containing MGBG was supplemented with spermidine. In contrast, when spermine was incorporated in a MS medium with MGBG, the rooting was achieved in both species, thus establishing spermine's clear role in the rooting of microshoots. An increase in peroxidase activity was observed during IBA and PUT-induced rooting. The performance of plants rooted on a medium containing 2.5 μM IBA was significantly better than those rooted on a medium containing 2.5 μM IBA and 100 μM PUT.