Changes In Peroxidase Activity During Adventitious Root Formation At The Base Of Mung Bean Cuttings

An attempt was made to identify the role of peroxidase activity as well as the changes of peroxidase (POX) isozymes that control adventitious root formation at the base of hypocotyl cuttings of mung bean (Vigna radiata L. cv. 105). Three phases of the adventitious root formation process were identified; induction (0-24 h), initiation (24-72 h) and expression (after 72 h). The lower peroxidase activity during the induction period (0-24 h) corresponded with the first peak of IAA at 24 h which indicated termination of the induction phase. A peak of peroxidase activity with low IAA levels at 72 h signaled the termination of the initiation phase. After 72 h, peroxidase activity declined and IAA levels increased slowly and this was characterized as the expression phase. Exogenous application of auxin IBA (10 -5 M) or polyamine putrescine (PUT, 10 -4 M) had an effect on increasing the number of adventitious root than control. Compared with controls IBA (10 -5 M) or PUT (10 -4 M) treated cuttings exhibited increased levels of peroxidase activities also. The change in isozymes pattern were observed after 24 h of cuttings. The Relative Mobility Fraction (Rmf) of isozymes also increased and extra peaks of band intensity (OD) were also appeared during initiation and expression phases of rooting in Vigna hypocotyl regions treated with IBA (10 -5 M) or PUT (10 -4 M) than control.