Effect Of Exogenous Spermindine On Antioxidant Enzyme Activities And Polyamine Content In Nitraria Sibirica Pall. Seedlings Under Salt Stress

Polyamines mainly include putrescine (Put), spermidine (Spd), spermine (Spm), they are ubiquitous low molecular aliphatic amines generated in organism metabolism. They participate plant growth and development, and closely relate to stress resistance. Nitraria sibirica Pall.(Zygophyllaceae, Nitraria L.) distributes at desert area in Northwest China, it has the function of sand fixation and saline soil restoration. To further elucidate the relationship of spermidine and salt tolerance of halophyte Nitraria sibirica Pall. under different levels of salinity in hydroponics condition, we studied the effect of spermidine on malondialdehyde (MDA), superoxide anion and the antioxidant enzyme system in leaves of N. Sibirica seedlings. The results are as follows:1.In treatment groups(100mmol·L-1NaCl and200mmol·L-1NaCl), the activities of superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) in leaves of N. Sibirica seedlings and the activity of root system were significantly increased, while the content of the MDA and superoxide dismutase in leaves were reduced in5th d after foliage spray of spermidine (0.1mmol·L-1). 2. The contents of endogenous free Spd and Spm were significantly increased after foliage spray of spermidine(0.1mmol·L-1), In50mmol·L-1NaCl treatment groups of improving the greatest extent.,and the contents of endogenous Put was significantly increased with salt concentration increase, lowest in treatment groups of300mmol·L-1NaCl.3. The content of free Put is very low and under the detection concentration. Spd and Spm are responsable to salt stress in halophyte N. Sibirica.The present study suggested that exogenous spermidine can effectively reduce the injury to N.sibirica and enhance the adaptability in salt environment.