摘要
一氧化氮(NO)作为生物活性分子,广泛参与各种生物和非生物胁迫.采用营养液培养,研究了Cu胁迫下外源NO介导的番茄还原型谷胱甘肽-植物螯合肽(GSH-PCs)合成途径中相关酶活性及代谢产物的变化.结果表明:与对照(CK)相比,Cu胁迫可以显著激活番茄体内γ-谷氨酰半胱氨酸合成酶(γ-ECS)、谷胱甘肽合成酶(GS)活性,根系GSH、PCs含量急剧升高,且随着处理时间的延长,γ-ECS、GS活性和GSH、PCs含量呈持续上升趋势;添加外源硝普钠(SNP,NO供体)可以进一步提高Cu胁迫下番茄根系γ-ECS、GS活性,促进GSH、PCs的合成,增强清除过氧化物的能力,并螯合过多的Cu2+,降低其生物毒性.叶片中的GSH-PCs代谢变化在一定程度上滞后于根系.外源丁硫氨酸-亚砜亚胺(BSO,GSH合成抑制剂)显著抑制根系γ-ECS活性,添加SNP可以显著逆转根系中BSO对GSH和PCs合成的抑制,对叶片中PCs合成的影响较小.Cu胁迫下,外源NO可能启动了某些信号机制,并通过激活或增强GSH-PCs合成途径中的酶促和非酶促系统,降低过多的Cu2+的生物毒性和氧化伤害.
Nitric oxide （NO）, as a biologically active molecule, widely involved in the biotic and abiotic stresses. By using solution culture, this paper reported the dynamic changes in enzyme activity and metabolites related to GSH-PCs synthesis way mediated by exogenous NO in tomato （Lycopersicon esculentum）. The results showed that exogenous NO could affect the metabolic pathway of GSH-PCs in tomato seedlings under copper stress. Compared with CK, the activity of γ-ECS and GS was significantly activated, consequently resulting in a sharp rise in GSH and PCs contents in tomato root. Moreover, γECS and GS activity, GSH and PCs contents constantly rise with the extension of processing time under copper stress. Adding exogenous SNP could further improve γ-ECS and GS activity in tomato, and promote the production of GSH and PCs, which contributed to enhancing the ability of removing superoxide and chelating excess Cu2＋ to reduce its biological toxicity. To a certain extent, GSH-PCs metabolic changes in leaf lagged behind that in roots. Exogenous BSO could significantly inhibit γ-ECS activity, and applying SNP could significantly reverse the inhibition on GSH and PCs synthesis by BSO. BSO had little effects on PCs content in leaf. Under copper stress, exogenous NO may initiate a signal mechanism and reduce the biotoxicity and oxidative damage caused by excessive Cu2＋ by activating or enhancing the enzymatic and non-enzymatic systems in the GSH-PCs synthesis path.
出处
《应用生态学报》
CAS
CSCD
北大核心
2014年第9期2629-2636,共8页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(31201619)资助
