摘要
以组织培养的菹草无菌苗为实验材料,研究了外源Ca(NO3)2对汞(Hg)胁迫下菹草无菌苗抗氧化酶系统、可溶性蛋白、总抗氧化能力(T-AOC)、非蛋白巯基(NP-SH)、植物络合素(PCs)以及脯氨酸代谢的调节效应。结果表明:(1)Hg胁迫使菹草体内过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)及谷胱甘肽还原酶(GR)活性明显降低,但超氧化物歧化酶(SOD)及过氧化物酶(POD)的活性并没有明显变化。外源添加25 mmol·L-1Ca(NO3)2后,明显提升了SOD、POD、APX及GR的活性;(2)Hg胁迫使菹草体内可溶性蛋白含量及T-AOC大幅降低,并引起NP-SH和PCs大量积累。外添Ca(NO3)2则有效减缓可溶性蛋白含量及T-AOC的下降,显著降低NP-SH和PCs水平;(3)脯氨酸是植物体内重要的渗透调节物质,外源Ca添加后,脯氨酸代谢关键酶吡咯啉-5-羧酸合成酶(P5CS)及δ-鸟氨酸转氨酶(OAT)活性显著增加,脯氨酸含量显著高于对照组。以上结果表明,Hg胁迫打破了菹草无菌苗抗氧化酶系统的内在平衡,而外添Ca(NO3)2有效促进了可溶性蛋白合成,提高了抗氧化酶活性和抗氧化物质含量,使菹草无菌苗维持较高的总抗氧化能力,并通过调节脯氨酸代谢来减轻Hg胁迫对菹草的伤害,增强植物对重金属Hg的耐受能力。
Sterile seedlings of Potamogeton crispus L. were cultured by tissue culture technique, to investigate the effects of exogenous calcium （Ca） application on antioxidase system, soluble protein, antioxidant capacity （T-AOC）, non-protein thiols （ NP-SH）, phytochelatins （PCs） and proline metabolism of leaves of the tested plants under Hg stress. The results showed that, Hg stress resulted in a serious imbalance of antioxidase system, such as restrained activities of cata- lase （CAT）, ascorbatc peroxidase （APX）, and glutathion reductase （GR）, while no obvious changes were observed in superoxide dismutase （SOD） and peroxides （POD） activities. Mean- while, 25 mmol · L-1 exogenous application of Ca markedly retarded the degradation of antioxi- dases and effectively enhanced SOD, POD, APX and GR activities in P. crispus. Hg treatment severely reduced the soluble protein content and T-AOC, as well as promoted a substantial accu- mulation of NP-SH and PCs. Application of exogenous Ca apparently reversed this situation and decreased the levels of NP-SH and PCs. Proline is an important osmolyte in aquatic plants on ex- posure against abiotic stresses. Addition of exogenous Ca increased proline accumulation signifi- cantly by activating pyrroline-5-carboxylate （ P5 CS） and rnithine-δ-aminotransferase （OAT） ac- tivities. Our results demonstrated that Hg disturbed the intrinsic balance of antioxidant defense system in the tested plants. The supplement of exogenous Ca relieved the phytotoxicity of Hg to P. crispus by promoting the synthesis of soluble protein, increasing the activities of antioxidant enzymes and the contents of antioxidant substances, maintaining a high total antioxidant capacity and involving in regulation of a series of physiological and biochemical mechanisms, particularly proline metabolism.
出处
《生态学杂志》
CAS
CSCD
北大核心
2014年第2期380-387,共8页
Chinese Journal of Ecology
基金
江苏高校优势学科建设工程项目(164320H106)资助
关键词
汞
钙
氧化胁迫
脯氨酸代谢
mercury
calcium
oxidative stress
proline metabolism.
