外源NO介导Cu2＋胁迫下番茄幼苗活性氧与内源NO代谢的研究

Study on the Metabolism Pathway of ROS and NO of Tomato Seedlings Mediated by Exogenous NO under Copper Ion Stress

采用营养液培养方法,研究Cu^(2+)胁迫下外源一氧化氮(nitric oxide,NO)介导的番茄幼苗活性氧及NO代谢途径。结果表明:在Cu^(2+)胁迫下,番茄叶片和根系氧自由基含量增加,NO释放量以及硝酸还原酶(nitrate reductase,NR)和一氧化氮合酶(nitric oxide synthase,NOS)活性降低。外源NO能提高Cu^(2+)胁迫下番茄叶片NR和NOS活性,促进NO的产生,根系NOS活性及NO产量也同时上升。外源NO使精氨酸含量显著增加,而Hb(牛血红蛋白,NO清除剂)可部分抵消NO的促进作用,使Cu^(2+)+SNP+Hb处理下番茄精氨酸含量显著下降。可见,外源NO的加入可通过酶促和非酶促途径促进Cu^(2+)胁迫下NO的合成,介导NO信号调控网络,调节内源NO、精氮酸和活性氧代谢途径,从而缓解过多Cu^(2+)引起的氧化伤害。

By using solution culture method, this study investigated the effects of exogenous nitric oxide on reactive oxygen and the metabolism of NO of tomato seedling. The results showed that under copper ion stress, the production rate of oxygen radical both in leaves and roots of tomato seedlings increased ,while the production of NO, the activities of NR and NOS in tomato seedling reduced. The application of nitric oxide promoted the activity of NOS in leaves and roots and activity of NR in leaves, thus increased the production of NO. Meanwhile, the exogenous NO significantly affected arginine metabolism and led to an upward tenden- cy of arginine. Under the Cu ＋ SNP ＋ Hb treatment, Hb （the scavenger of NO） could partly counteract the effect of exogenous NO, which made arginine decrease. In conclusion, adding exogenous NO could improve the production of NO through enzymatic and non-enzymatic pathway, which mediated the NO signal networks regulating the metabolic pathway among the NO, reactive oxygen and arginine metabolism so as to relieve oxidative damage caused by excessive copper ion.