Effect of Polyamine on Pigmentation, Reactive Oxidative Species and Antioxidant under Drought in Maize (Zea mays L.)

To examine polyamines (PAs) effect in modulating the drought induced by polyethylene glycol (PEG) in maize (Zea mays L.) seedlings (variety Khoibhutta, 8 day seedlings grown in petri dish in incubator) were subjected to 20% PEG (polyethylene glycol) followed by 20 µmol PAs, Putrescine (Put), Spermidine (Spd) and Spermine (Spm) with PEG solution for 48 hours. Sharp decrease in Relative Water Content (RWC), Chl a, Chl b, carotenoid (Car) and total pigment content was observed under drought compared to control condition, while PAs application reversed their decreasing trends. PEG significantly increased Reactive Oxidative Species (ROS) [superoxide (O2•−) and H2O2], Methyl Glyoxal (MG), Melondialdehyde (MDA) and Lipoxigenase (LOX) activity, while Pas decreased the contents considerably (except MG) as compared to those under drought. Drought increased proline content, which was further augmented in PA treatments. PAs failed to incline glyoxalase’s (Gly-I and Gly-II) activities, reduced under PEG. The activity and western blot confirmed the accumulation of Glutathione S-Transferase (GST) under drought, but PAs failed to augment the activity. Ascorbic Acid (AsA) and Glutathione (GSH) got oxidized into Dehydroascorbate (DHA) and oxidized Glutathione (GSSG) under drought but PAs effectively maintained homeostasis. Superoxide Dismutase (SOD), Peroxidase (POD), Ascorbate Peroxidase (APX), Glutathione Peroxidase (GPX), Monodehydroascorbatereductase (MDHAR), Dehydroascorbatereductase (DHAR), and Glutathione Reductase (GR) inclined in drought stressed seedlings, while Catalase (CAT) activity decreased under drought. PAs addition increased SOD, POD, GPX, CAT, MDHAR, and GR activities, but declined DHAR activity. These findings suggested important role of PAs in increasing tolerance under short term drought by modulating antioxidant effect.