褪黑素对低温胁迫后菘蓝种子苗抗氧化性影响

Effects of exogenous melatonin on antioxidant activities in Isatis indigotica fort.seedlings after low temperature stress

目的以低温胁迫处理的菘蓝种子为起始材料,研究外源褪黑素对萌发种子苗的生长及抗氧化性的影响。方法褪黑素处理低温浸种菘蓝种子,测定萌发的种子幼苗中丙二醛含量以及相关抗氧化酶活性;测定植株根长和IAA含量。结果 10～500μmol/L适宜浓度的外源褪黑素可降低低温处理后菘蓝幼苗中的丙二醛含量,增强过氧化氢酶和过氧化物酶活性,增加内源激素IAA的含量并促进幼苗根的伸长。其中500μmol/L褪黑素作用最显著,随着其浓度的进一步升高,褪黑素植物保护作用减弱。结论外源褪黑素处理菘蓝种子能降低膜脂过氧化水平,提高抗氧化酶的活性,减轻冷胁迫对幼苗生长过程中的氧化损伤,并且褪黑素可能通过影响植物体内IAA水平,刺激植物根生长。

Aim Melatonin mediates many physiological processes the response to oxidative stress of Isatis indigotica Fort. seedlings in plants. Its role in regulating the growth and after low temperature stress were investigated. Methods Exogenous melatonin was applied to the seeds of Isatis indigotiea Fort. under 4℃ and its effects on the antioxidant activity, roots growth and endogenousindole-3-aeeticacid （IAA） levels of the seedlings were investiga ted. Results The results showed that 10 -500 μmol/L exogenous melatonin could significantly decrease the con- tent of malonaldehyde （ MDA）, meanwhile enhance the activities of catalase （CAT） and peroxidase （POD） of the seedlings, which prevented the plants from oxidative damage under low temperature stress. In addition, for primed seeds treated with 500 μmol/L melatonin before chill stressed, a relative auxinic activity of melatonin by elevating the endogenous levels of free IAA was observed, and the root growth in seedlings were therefore stimulated. Conclusion These results indicate that melatonin plays an important role in regulating antioxidant activities and stimulating root growth after treatment with low temperature.