外源甲基紫精对盐胁迫下黄瓜叶片抗氧化酶与DNA甲基化的影响
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摘要
土壤盐渍化是一个世界性的资源环境和生态问题。因此,植物耐盐性研究具有重要的意义。本实验以温室型黄瓜品种“春光2号”为材料,报告了外源甲基紫精缓解植株的盐胁迫,研究了外源甲基紫精对盐胁迫下黄瓜叶片抗氧化酶与DNA甲基化的影响,分离了盐胁迫下外源甲基紫精诱导的甲基化差异片段,然后对这些差异片段进行克隆、测序和序列的生物信息学分析。本文从抗氧化酶、整个基因组水平上初步揭示外源甲基紫精缓解盐胁迫的机制,为利用甲基化差异基因打下基础,为外源甲基紫精在黄瓜耐盐生产中的应用提供依据,并为其它外源物质缓解植物逆境胁迫的机制研究提供参考。
实验在黄瓜幼苗长至两叶一心时进行,用10μM甲基紫精(PQ)浇灌黄瓜幼苗后于100μmol m-2 s-1光照下处理1 h,然后分别用水和营养液冲洗植株各6次,将黄瓜幼苗在暗处放置24 h后浇灌100mM NaCl,进行盐处理。盐胁迫处理两天后取第二片真叶,测定其超氧化物歧化酶(SOD,EC 1.15.1.1)、愈创木酚过氧化物酶(GPX,EC 1.11.1.7)、过氧化氢酶(CAT,EC 1.11.1.6)、谷胱甘肽还原酶(GR,EC 1.6.4.2)、谷胱甘肽过氧化物酶(GSH-Px, EC 1.11.1.9)、脱氢抗坏血酸还原酶(DHAR, EC 1.8.5.1)、单脱氢抗坏血酸还原酶(MDHAR, EC 1.6.5.4)和抗坏血酸过氧化物酶(APX, EC 1.11.1.11)的活性,检测叶片中丙二醛(MDA)、内源H2O2、抗坏血酸(AsA)还原型谷胱甘肽(GSH)和超氧阴离子(O2.-)的水平。另外,实验提取黄瓜叶片基因组DNA,利用甲基化敏感扩增多态性(MSAP)技术研究黄瓜叶片基因组DNA甲基化的水平和状态变化,对盐胁迫下甲基紫精预处理诱导的DNA甲基化差异片段进行回收,克隆和测序分析。主要结果如下:
1、甲基紫精预处理对盐胁迫下黄瓜叶片抗氧化酶的影响
盐胁迫严重抑制了黄瓜幼苗的生长,使地上部和根系干重均显著下降;PQ处理后再进行盐胁迫的黄瓜幼苗中,地上部和根系干重明显上升,PQ处理缓解了盐胁迫对黄瓜生长的抑制作用。PQ处理提高了盐胁迫下黄瓜叶片抗氧化酶SOD、GPX、CAT、APX、GSH-Px、DHAR、MDHAR和GR的活性,增加了盐胁迫下抗氧化物AsA和GSH的含量、还原型AsA与氧化型AsA比值以及GSH与GSSG的比值,同时显著降低了盐胁迫下黄瓜叶片MDA的含量、O2.-生成速率以及H2O2的含量,缓解了盐胁迫下ROS对黄瓜叶片的伤害。因此,我们推断,盐胁迫下PQ处理通过提高黄瓜幼苗抗氧化酶的活性和抗氧化物的含量,降低活性氧的含量,进而缓解了盐胁迫诱导的膜脂过氧化损伤,减轻了盐胁迫对黄瓜幼苗生长的抑制,提高了黄瓜幼苗的耐盐性。
2、甲基紫精预处理对盐胁迫下黄瓜叶片DNA甲基化的影响
利用32对引物对黄瓜叶片基因组DNA甲基化进行了MSAP分析:共扩增出1324条带,对照、PQ预处理、salt处理以及PQ+salt处理的总甲基化比率分别为19.8%、19.9%、21.5%和20.4%。在盐胁迫下,黄瓜植株DNA甲基化水平发生改变;外源甲基紫精预处理黄瓜幼苗后,能诱导盐胁迫下黄瓜DNA发生去甲基化。对部分甲基化差异片段回收、克隆、测序及序列比对后,发现6条片段与植物响应逆境胁迫的基因序列具有较高的同源性。
Salt tolerance of plants is of great significance as soil salinization is one of the most important global environmental and ecological problems. Cucumber (Cucumis sativus L.) cv. Chunguang no. 2 was cultivated to study whether exogenous paraquat (PQ) could protect plants from salt stress and whether the protection was associated with the increasing of antioxidant enzymes activities and the changes of DNA methylation. We also aimed to clone the methylation polymorphic fragments and analyze their sequence by using bioinformatics. Our work might help to elucidate the mechanisms of salt stress mitigated by PQ on the sides of antioxidant enzymes and DNA methylation. It also could lay the foundations for applying methylation polymorphic genes and exogenous PQ to salt-resisting cultivation of cucumbers and give references to studying the mechanisms of stress mitigated by other substances.
At the two-leaf stage, cucumber seedlings were selected and pretreated with 10μM PQ under moderate light (100μmol m-2 s-1) for 1 h. After rinsed 6 times with water and nutrient solution, cucumber plants were kept in darkness for 24 h. Then, the cucumbers were watered with 100 mM salt for 2 d. Samples of the second leaf was used to determine the activities of antioxidants such as superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6), dehydrateascorbate reducatase (DHAR, EC 1.8.5.1), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), glutathione reductase (GR, EC 1.6.4.2), ascorbic acid (AsA) and reduced glutathione (GSH). The leaf samples were also used to assay the cntents of malondialdehyde (MDA), hydrogen peroxide (H_2O_2) and superoxide anion (O_2.-). After extracting genomic DNA from the second leaves, DNA methylation was surveyed by using the methylation-sensitive amplified polymorphism (MSAP) method. Then, DNA methylation polymorphic fragments were isolated, cloned and sequenced. Subsequently, homology search and sequence analysis were performed at the public database NCBI. The main results of this study were listed as the following:
1. Effects of paraquat on antioxidant enzymes in salt-stressed cucumber leaves
The growth of cucumber seedlings was inhibited observably by salt stress. The dry weights of shoot and root were significantly decreased under salt stress, while they were increased in PQ-pretreated stressed plants. So PQ pretreatment alleviated the inhibition of salt stress on the growth of cucumber seedlings. Under salt conditions, PQ pretreatment relieved oxidative stress as observed by the decreases in levels of MDA, H_2O_2 and O_2.-, which correlated with the increase in antioxidant defenses. Compared to the salt treatment, PQ pretreatment increased the activities of antioxidants such as SOD, GPX, CAT, APX, GSH-Px, DHAR, MDHAR, GR, ASA and GSH and also enhanced the ratios of reduced ASA/oxidized ASA and GSH/GSSG. Therefore, we proposed that the PQ pretreatment increased the activities of antioxidant enzymes under conditions of salt and thereby decreased the levels of ROS and improved the salt tolerance of cucumber seedlings.
2. Effects of paraquat on DNA methylation in salt stressed cucumber leaves
Thirty-two pairs of primers were used for MSAP analysis. Total of 1324 fragments were amplified, and the level of global DNA methylation in four treatments (control, PQ pretreatment, salt and PQ+salt treatments) were 19.8%, 19.9%, 21.5% and 20.4%, respectively. The levels of DNA methylation in cucumber plants were obviously changed under drought stress, while PQ pretreatment directionally induced the demethylation. After part of the methylated DNA fragments were cloned and sequenced, six fragments were found to be homologous to the functional protein, indicating that the fragments were involved in the process where PQ improved the salt tolerance of cucumber seedlings.
实验在黄瓜幼苗长至两叶一心时进行,用10μM甲基紫精(PQ)浇灌黄瓜幼苗后于100μmol m-2 s-1光照下处理1 h,然后分别用水和营养液冲洗植株各6次,将黄瓜幼苗在暗处放置24 h后浇灌100mM NaCl,进行盐处理。盐胁迫处理两天后取第二片真叶,测定其超氧化物歧化酶(SOD,EC 1.15.1.1)、愈创木酚过氧化物酶(GPX,EC 1.11.1.7)、过氧化氢酶(CAT,EC 1.11.1.6)、谷胱甘肽还原酶(GR,EC 1.6.4.2)、谷胱甘肽过氧化物酶(GSH-Px, EC 1.11.1.9)、脱氢抗坏血酸还原酶(DHAR, EC 1.8.5.1)、单脱氢抗坏血酸还原酶(MDHAR, EC 1.6.5.4)和抗坏血酸过氧化物酶(APX, EC 1.11.1.11)的活性,检测叶片中丙二醛(MDA)、内源H2O2、抗坏血酸(AsA)还原型谷胱甘肽(GSH)和超氧阴离子(O2.-)的水平。另外,实验提取黄瓜叶片基因组DNA,利用甲基化敏感扩增多态性(MSAP)技术研究黄瓜叶片基因组DNA甲基化的水平和状态变化,对盐胁迫下甲基紫精预处理诱导的DNA甲基化差异片段进行回收,克隆和测序分析。主要结果如下:
1、甲基紫精预处理对盐胁迫下黄瓜叶片抗氧化酶的影响
盐胁迫严重抑制了黄瓜幼苗的生长,使地上部和根系干重均显著下降;PQ处理后再进行盐胁迫的黄瓜幼苗中,地上部和根系干重明显上升,PQ处理缓解了盐胁迫对黄瓜生长的抑制作用。PQ处理提高了盐胁迫下黄瓜叶片抗氧化酶SOD、GPX、CAT、APX、GSH-Px、DHAR、MDHAR和GR的活性,增加了盐胁迫下抗氧化物AsA和GSH的含量、还原型AsA与氧化型AsA比值以及GSH与GSSG的比值,同时显著降低了盐胁迫下黄瓜叶片MDA的含量、O2.-生成速率以及H2O2的含量,缓解了盐胁迫下ROS对黄瓜叶片的伤害。因此,我们推断,盐胁迫下PQ处理通过提高黄瓜幼苗抗氧化酶的活性和抗氧化物的含量,降低活性氧的含量,进而缓解了盐胁迫诱导的膜脂过氧化损伤,减轻了盐胁迫对黄瓜幼苗生长的抑制,提高了黄瓜幼苗的耐盐性。
2、甲基紫精预处理对盐胁迫下黄瓜叶片DNA甲基化的影响
利用32对引物对黄瓜叶片基因组DNA甲基化进行了MSAP分析:共扩增出1324条带,对照、PQ预处理、salt处理以及PQ+salt处理的总甲基化比率分别为19.8%、19.9%、21.5%和20.4%。在盐胁迫下,黄瓜植株DNA甲基化水平发生改变;外源甲基紫精预处理黄瓜幼苗后,能诱导盐胁迫下黄瓜DNA发生去甲基化。对部分甲基化差异片段回收、克隆、测序及序列比对后,发现6条片段与植物响应逆境胁迫的基因序列具有较高的同源性。
Salt tolerance of plants is of great significance as soil salinization is one of the most important global environmental and ecological problems. Cucumber (Cucumis sativus L.) cv. Chunguang no. 2 was cultivated to study whether exogenous paraquat (PQ) could protect plants from salt stress and whether the protection was associated with the increasing of antioxidant enzymes activities and the changes of DNA methylation. We also aimed to clone the methylation polymorphic fragments and analyze their sequence by using bioinformatics. Our work might help to elucidate the mechanisms of salt stress mitigated by PQ on the sides of antioxidant enzymes and DNA methylation. It also could lay the foundations for applying methylation polymorphic genes and exogenous PQ to salt-resisting cultivation of cucumbers and give references to studying the mechanisms of stress mitigated by other substances.
At the two-leaf stage, cucumber seedlings were selected and pretreated with 10μM PQ under moderate light (100μmol m-2 s-1) for 1 h. After rinsed 6 times with water and nutrient solution, cucumber plants were kept in darkness for 24 h. Then, the cucumbers were watered with 100 mM salt for 2 d. Samples of the second leaf was used to determine the activities of antioxidants such as superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6), dehydrateascorbate reducatase (DHAR, EC 1.8.5.1), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), glutathione reductase (GR, EC 1.6.4.2), ascorbic acid (AsA) and reduced glutathione (GSH). The leaf samples were also used to assay the cntents of malondialdehyde (MDA), hydrogen peroxide (H_2O_2) and superoxide anion (O_2.-). After extracting genomic DNA from the second leaves, DNA methylation was surveyed by using the methylation-sensitive amplified polymorphism (MSAP) method. Then, DNA methylation polymorphic fragments were isolated, cloned and sequenced. Subsequently, homology search and sequence analysis were performed at the public database NCBI. The main results of this study were listed as the following:
1. Effects of paraquat on antioxidant enzymes in salt-stressed cucumber leaves
The growth of cucumber seedlings was inhibited observably by salt stress. The dry weights of shoot and root were significantly decreased under salt stress, while they were increased in PQ-pretreated stressed plants. So PQ pretreatment alleviated the inhibition of salt stress on the growth of cucumber seedlings. Under salt conditions, PQ pretreatment relieved oxidative stress as observed by the decreases in levels of MDA, H_2O_2 and O_2.-, which correlated with the increase in antioxidant defenses. Compared to the salt treatment, PQ pretreatment increased the activities of antioxidants such as SOD, GPX, CAT, APX, GSH-Px, DHAR, MDHAR, GR, ASA and GSH and also enhanced the ratios of reduced ASA/oxidized ASA and GSH/GSSG. Therefore, we proposed that the PQ pretreatment increased the activities of antioxidant enzymes under conditions of salt and thereby decreased the levels of ROS and improved the salt tolerance of cucumber seedlings.
2. Effects of paraquat on DNA methylation in salt stressed cucumber leaves
Thirty-two pairs of primers were used for MSAP analysis. Total of 1324 fragments were amplified, and the level of global DNA methylation in four treatments (control, PQ pretreatment, salt and PQ+salt treatments) were 19.8%, 19.9%, 21.5% and 20.4%, respectively. The levels of DNA methylation in cucumber plants were obviously changed under drought stress, while PQ pretreatment directionally induced the demethylation. After part of the methylated DNA fragments were cloned and sequenced, six fragments were found to be homologous to the functional protein, indicating that the fragments were involved in the process where PQ improved the salt tolerance of cucumber seedlings.
引文
1.陈花,吴俊林,李晓军.叶绿体中活性氧的产生和清除机制.现代生物医学进展, 2008(8): 1979-1981
2.陈沁,刘友良. GSH对盐胁迫大麦活性氧清除系统的保护作用.作物学报, 2000(26): 365-371
3.龚明,丁念诚,贺子义,刘友良.盐胁迫下大麦和小麦叶片脂质过氧化伤害与超微结构变化的关系.植物学报, 1989(31): 841-846
4.李双顺,林桂珠,林植芳.丙二醛对苋菜叶片光合作用的影响.植物生理学通讯, 1988(3): 41-44
5.李雪林,林忠旭,聂以春,郭小平,张献龙.盐胁迫下棉花基因组DNA表观遗传变化的MSAP分析.作物学报, 2009(35): 588-596
6.廖靖军,安成才,吴思,陈章良.查尔酮合酶基因在植物防御反应中的调控作用.北京大学学报, 2000(36): 566-574
7.潘雅姣,傅彬英,王迪,朱苓华,黎志康.水稻干旱胁迫诱导DNA甲基化时空变化特征分析.中国农业科学, 2009(42): 3009-3018
8.孙国荣,关旸,阎秀峰.盐胁迫对星星草幼苗保护酶系统的影响.草地学报, 2001(9): 34-38
9.王国莉,郭振飞.甲基紫精对水稻不同耐冷品种叶绿素荧光参数的影响.武汉植物学研究, 2008(26): 81-86
10.王素平,郭世荣,李璟.盐胁迫对不同基因型黄瓜幼苗生长的影响.江苏农业科学, 2006(2): 76-79
11.魏国强,朱祝军,方学智. NaCl胁迫对不同品种黄瓜幼苗生长、叶绿素荧光特性和活性氧代谢的影响.中国农业科学, 2004(37): 1754-1759
12.徐志防,罗广华,柯德森.超氧阴离子诱导的叶绿素荧光猝灭.生物化学与生物物理进展, 2002(29): 139-143
13.姚秋菊,张晓伟,赵小忠,魏国强.硅对盐胁迫下黄瓜叶片膜脂过氧化和活性氧清除系统的影响.华北农学报, 2008(23): 109-113
14.杨成丽,刘德立.植物甜蛋白Thaumatin研究进展.武汉植物学研究2001,(19): 153-157
15.杨金兰,柳李旺,龚义勤,黄丹琼,王峰,何玲莉.镐胁迫下萝卜DNA基因组甲基化敏感扩增多态性分析.植物生理与分子生物学学报, 2007(33): 219-226
16.於丙军,刘友良.盐胁迫对一年生盐生野大豆幼苗活性氧代谢的影响.西北植物学报, 2003(23): 18-22
17.张其德.盐胁迫对植物及其光合作用的影响(上).植物杂志, 1999(6), 32-33
18.赵福庚,何龙飞.植物逆境生理生化.北京化工出版社, 2004p55-60
19.郑小梅,伍宁丰. DNA甲基化作用的生物学功能.中国农业科技导报, 2009(11): 33-39
20.宰学明,吴国荣,陆长梅等. Ca2 +对花生幼苗耐热性和活性氧代谢的影响.中国油料作物学报, 2001(23): 46-50
21. Asada K, Takahashi M. Production and scavenging of active oxygen in photosynthesis. In: Kyle DJ, Osmond CB, Arntzen CJ, editors. Photoinhibition. Amsterdam: Elsevier Science, 1987p227-287
22. Asada K.The water-water cycle in chloroplasts: scavenging of active oxygens and dissipation of excess photons. Annu Rev Plant Physiol Plant Mol Biol, 1999(50): 601-639
23. Asada K, Endo T, Mano J, Miyake C. Molecular mechanisms for relaxation of and protection from light stress. In: Satoh K, Murata N (eds) Stress responses of photosynthetic organisms. Elsevier Science BV, 1998p37-52
24. Ananieva EA, Christov KN, Popova LP. Exogenous treatment with salicylic acid leads to increased antioxidant capacity in leaves of barley plants exposed to paraquat. J Plant Physiol, 2004(161): 319-328
25. Azevedo Neto AD, Prisco JT, Enéas-Filho J, Abreu CEB, Gomes-Filho E. Effect of salt stress on antioxidative enzymes and lipid peroxidation in leaves and roots of salt-tolerant and salt-sensitive maize genotypes. Environ Exp Bot, 2006(56): 87-94
26. Aufsatz W, Mette MF, Matzke AJ. et al. The role of MET1 in RNA-directed de novo and maintenance methylation of CG dinucleotides.Plant Molecular Biology, 2004(54): 793-804
27. Bartee L, Malagnac F, Bender J. Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and silencing of an endogenous gene. Genes and Development, 2001(15): 1753-1758
28. Blumwald E, Aharon GS, Apse MP. Sodium transport in plant cells. Biochim Biophys Acta, 2000(1465): 140-151
29. Bernt E, Bergmeyer HU. Inorganic peroxides. In: Bergmeyer HU, editor. Methods of enzymatic analysis. New York: Academic Press, 1974p68-88
30. Bhandal IS, Malik CP. Potassium estimation, uptake, and its role in the physiology and metabolism of flowering plants. lant Physiol. Plant Mol boil, 1992(43): 83-116
31. Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein–dye binding. Anal Biochem, 1976(72): 248-254
32. Boyko A, Kovalchuk I. Epigenetic control of plant stress response. Environ Mol Mutagen, 2008(49): 61-72
33. Bowler C, Montagu MV, Inze D. Superoxide dismutase and stress tolerance. Annu. Rev. Plant Physiol. Plant Mol. Biol, 1992(43): 83-116
34. Cao X, Aufsatz W, Zilberman D. et al. Role of the DRMand CMT3 methyltransferases in RNA-directed DNA methylation. Current Biology, 2003(13): 2212-2217
35. Casano LM, Martín M, Zapata JM, Sabater B. Leaf age- and paraquat concentration-dependent effects on the levels of enzymes protecting against photooxidative stress. Plant Sci, 1999(149): 13-22
36. Cervera MT, Ruiz-García L, Martínez-Zapater JM. Analysis of DNA methylation in Arabidopsis thaliana based on methylation-sensitive AFLP markers. Mol Genet Genomics, 2002(268): 543-552
37. Chagas RM, Silveira JAG, Rafael V, Ribeiro RV, Vitorello VA, Carrer H. Photochemical damage and comparative performance of superoxide dismutase and ascorbate peroxidase in sugarcane leaves exposed toparaquat-induced oxidative stress. Pestic Biochem Physiol, 2008(90): 181-188
38. Chan SW, Henderson IR, and Jacobsen SE. Gardening the genome: DNA methylation in Arabidopsis thaliana. Nat Rev Genet, 2005(6): 351-360
39. Choi SM, Jeong SW, Jeong WJ, Kwon SY, Chow WS, Park YI. Chloro-plast Cu/Zn-superoxide dismutase is a highly sensitive site in cucumber leaves chilled in the light. Planta, 2002(216): 315-324
40. Cramer GR, L?uchli A, Polito VS. Displacement of Ca2+ by Na+ from the plasmalemma of root cells-a primary response to salt stress.Plant Physiology, 1985(79): 207-211
41. Curradi M, Izzo A, Badaracco G., Landsberger N. Molecular mechanisms of gene silencing mediated by DNA methylation. Mol Cell Biol, 2002(22): 3157-3173
42. Dhindsa RS, Plumb-Dhindsa P, Thorpe TA. Leaf senescence: correlated with increase leaves of membrane permeability and lipid peroxidation and decreased levels of superoxide dismutase and catalase. J Exp Bot, 1981(32): 93-101
43. Diaz-Vivancos P, Rubio M, Mesonero V, Periago PM, Ros BarcelóA, Martínez-Gómez P, Hernández JA. The apoplastic antioxidant system in Prunus: response to plum pox virus. J Exp Bot, 2006(57): 3813-3824
44. Djanaguiraman M, Devi DD, Shanker AK, Sheeba JA, Bangarusamy U. Selenium-an antioxidative protectant in soybean during senescence. Plant Soil, 2005(272): 77-86
45. Dyachenko O, Zakharchenko N, Shevchuk T. et al. Effect of hypermethylation of CCWGG sequences in DNA of Mesembryanthemum crystallinum plants on their adaptation to salt stress. Biochemistry (Moscow) 2006(71): 461-465
46. Doulis AG, Debian N, Kingston-Smith AH, Foyer CH. Differential localization of antioxidants in maize leaves. Plant Physiol, 1997(114): 1031-1037
47. Elstner EF, Heupel A. Inhibition of nitrite formation from bydroxylam- moniumchloride: a simple assay for superoxide dismutase. Anal Biochem, 1976(70): 616-620
48. Ekmekci Y, Terzioglu S. Effects of oxidative stress induced by paraquat on wild and cultivated wheats. Pestic Biochem Physiol, 2005(83): 69-81
49. Finnegan EJ, Peacock WJ, Dennis ES. DNA methylation, a key regulator of plant development and other processes. Curr Opin Genet Dev, 2000(10): 217-223
50. Finnegan EJ, Kovac KA. Plant DNA methyltransferases. Plant Molecular Biology, 2000(43): 189-201
51. Flowers TJ, Troke PF, Yeo AR. The mechanism of salt tolerance in halophytes. Annu Rev Plant Physiol, 1977(28): 89-121
52. Foyer CH, Descourvieres P, Kunert KJ. Protection against oxygen radicals: an important defence mechanism studied in transgenic plants. Plant Cell Environ, 1994(17): 507-523
53. Foyer CH, Halliwell B. The presence of glutathione and glutathione reductase in chloroplasts: A proposal role in ascorbic acid metabolism. Planta, 1976(133): 21-25
54. Foyer CH, Lopez-Delgado H, Dat JF, Scott IM. Hydrogen peroxide and glutathione-associated mechanisms of acclamatory stress tolerance and signaling. Physiol Plant, 1997(100): 241-254
55. Ge CL, Yang XY, Liu XN, Sun JH, Luo S, Wang ZG. Effect of heavy metal on levels of methylation in DNA of rice and wheat. J Plant Physiol Mol Biol, 2002(28): 363-368
56. Gong HJ, Chen M, Chen GC. et al. Effects of silicon on growth of wheat under drought. Plant Nutr, 2003(26): 1055-1063
57. Gonzalgo ML, Liang GN. Identification and characterization of differentially methylated regions of genomic DNA by methylation-sensitive arbitrarily primed PCR. Cancer Res, 1997(57): 594-599
58. Gossett DR, Banks SW, Millhollon EP, Lucas MC. Antioxidant response to NaCl stress in a control and a NaCl-tolerant cotton cell line grown in the presence of paraquat, buthionine sulfoximine and exogenous glutathione. Plant Physiol, 1996(112): 803-809
59. Hai P, Jing Z. Plant genomic DNA methylation in response to stresses: Potential applications and challenges in plant breeding. Progress in Natural Science, 2009(19): 1037–1045
60. Hoque MA, Banu MNA, Okuma E, Amako K, Nakamura Y, Shimoishi Y, Murata Y. Exogenous proline and glycinebetaine increase NaCl-induced ascorbate-glutathione cycle enzyme activities, and proline improves salt tolerance more than glycinebetaine in tobacco Bright Yellow-2 suspension-cultured cells. J Plant Physiol, 2007(164): 1457-1468
61. Howell C, Bestor T, Ding F. et al. Genomic imprinting disrupted by a maternal effect mutation in the Dnmt1 gene. Cell, 2001(104): 829-838
62. Hwang SY, Lin HW, Chern RH, Lo HF, Li L. Reduced susceptibility to water logging together with high-light stress is related to increases in superoxide dismutase and catalase activities in sweet potato. Plant Growth Regul, 1999( 27): 167-172
63. Janda T, Szalai G, Antunovics Z, Horváth E, Páldi E. Effect of benzoic acid and aspirin on chilling tolerance and photosynthesis in young maize plants. Maydica, 2000(45): 29-33
64. Jaenisch R. DNA methylation and imprinting: why bother? Trends Genet, 1997(13): 323-329
65. Jones PA, Takai D. The role of DNA methylation in mammalian ep igenetics. Science, 2001(293): 1068-1070
66. Kampfenkel K, Montagu MV, Inze D. Extraction and determination of ascorbate and dehydroascorbate from plant tissue. Anal Biochem, 1995(225):165-167
67. Kankel M, Ramsey D, Stokes T. et al. Arabidopsis MET1 cytosine methyltransferase mutants. Genetics, 2003 (163): 1109-1122
68. Kovarik A, Koukalova B, Bezdek M. et al. Hypermethylation of tobacco heterochromatic loci in response to osmotic stress. Theor Appl Genet, 1997(95): 301-306
69. Labra M, Ghiani A, Citterio S. et al. Analysis of cytosine methylation pattern in response to water deficit in pea root tips. Plant Biol, 2002(4): 694-699
70. Lee DH, Kim YS, Lee CB. The inductive responses of the antioxidant enzymes by salt stress in the rice (Oryza sativa L.). J Plant Physiol , 2001(158): 737-745
71. Li X Q, Xu M L, Korban S S. DNA methylation profiles differ between field- and in vitro-grown leaves of apple. Journal of Plant Physiology, 2002(159): 1229-1234
72. Liang YC. Eeffcts of silicon on enzyme activiy and sodium,Potassium and calcium concentration in barely under saltstress. Palnt and soil, 1999(29): 217-224
73. Liang YC, Hu F, Yang MC. et al. Antioxidative defenses and water deficit-induced oxidative damage in rice (Oryza sativa L.) growing on non-flooded paddy soils with ground mulching. Plant and Soil, 2003(257): 407-416
74. Liang YC, Chen Q, Liu Q. et al. Exogenous silicon (Si) increases antioxidant enzyme activity and reduces lipid peroxidation in roots of salt-stressed barley (Hordeum vulgare L.). Journal of Plant Physiology, 2003(160): 1157-1164
75. Liau YJ, Wen L, Shaw JF, Lin CT. A highly stable cambialistic-superoxide dismutase from Antrodia camphorata: expression in yeast and enzyme properties. J Biotechnol, 2007(131): 84-91
76. Lindroth A, Cao X, Jackson J. et al. Requirement of CHROMOMETHYLASE3 for maintenance of CpXpG methylation. Science, 2001(292): 2077-2080
77. Luster DG, Donaldson RP. Orientation of electron transport activities inthe membrane of intact glyoxysomes isolated from castor bean endosperm. Plant Physiol, 1987(85): 796-800
78. Mcclelland M, Nelson M, Raschke E. Effect of site-specific modification on restriction endonucleases and DNA modification methyltransferases. Nucleic Acids Research, 1994(22): 3640-3459
79. Martinez CA, Loureiro ME, Oliva MA, Maestri M. Differential responses of superoxide dismutase in freezing resistant Solanum curtilobum and freezing sensitive Solanum tuberosum subjected to oxidative and water stress. Plant Science, 2001(160): 505-551
80. Matzke M, Aufsatz W, Kanno T. et al. Genetic analysis of RNA-mediated transcriptional gene silencing. Biochimica et Biophysica Acta, 2004(1677): 129-141
81. Mascher R, Lippmann B, Holzinger S, Bergmann H. Arsenate toxicity: effects on oxidative stress response molecules and enzymes in red clover plants. Plant Sci, 2002(163): 961-969
82. Meyer P, Saedler H. Homology-dependent gene silencing in plants. A nnu. Rev. Plant Physiol. Plant Mol Biol, 1996(47): 23-48
83. Mittler, R. Oxidative stress, antioxidants and stress tolerance. Trends Plant Sci, 2002(7): 405-410
84. Munns R. Comparative physiology of salt and water stress. Plant Cell Environ, 2002(28): 239-250
85. Molina A, Bueno P, Marin MC, Rodriguez-Rosales MP, Belver A, Venema K, Donaire JP. Involvement of endogenous salicylic acidcontent, lipoxygenase and antioxidant enzyme activities in the response of tomato cell suspension cultures to NaCl. New Phytol, 2002(156): 409-415
86. M?ller IM. Plant mitochondria and oxidative stress: electron transport, NADPH turnover, and metabolism of reactive oxygen species. Annu Rev Plant Physiol Plant Mol Biol, 2001(52): 561-591
87. Neill S, Desikan R, Hancock J. Hydrogen peroxide signaling. Curr Opin Plant Biol, 2002(5): 388-395
88. Newell-Price J, Clark AJ, King P. DNA methylation and silencing of gene expression. Trends Endocrinol Metab, 2000(11): 142-148
89. Noctor G, Foyer CH. Ascorbate and glutathione: keeping active oxygen under control. Annu.Rev. Plant Physiol. Plant Mol Biol, 1998(49): 249-79
90. Okano M, Bell D, Haber D. et al. DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development. Cell, 1999 (99): 247-257
91. Ohkawa H, Ohishi N, Yagi K. Assay for lipid peroxides in animal tissue by thiobarbituric acid reaction. Anal Biochem, 1979(95): 351-358
92. Rassoulzadegan M, Grandjean V, Gounon P, Vincent S, Gillot I, Cuzin F. RNA-mediated non-mendelian inheritance of an epigenetic change in the mouse. Nature, 2006(441): 469-474
93. Pelissier T, Thalmeir S, Kempe D. et al. Heavy de novo methylation at symmetrical and non- symmetrical sites is a hallmark of RNA-directed DNA methylation. Nucleic Acids Research, 1999(27): 1625-1634
94. Pereira GJG, Molina SMG, Lea PJ, Azevedo RA. Activity of antioxidant enzymes in response to cadmium in Crotalaria juncea. Plant Soil, 2002(239): 123-132
95. Perelman A, Dubinsky Z, Martínez R. Temperature dependence of superoxide dismutase activity in plankton. J Exp Mar Biol Ecol, 2006(334): 229-235
96. Portis E, Acquadro A, Comino C, Lanteri S. Analysis of DNA methylation during germination of pepper (Capsicum annuum L.) seeds using methylation-sensitive amplification polymorphism (MSAP). Plant Sci, 2004(166): 169-178
97. Ramiro DA, Guerreiro-Filho O, Mazzafera P. Phenol contents, oxidase activities, and the resistance of coffee to the leaf miner Leucoptera coffeella. J Chem Ecol, 2006(32): 1977-1988
98. Razin A. CpG methylation, chromatin structure and gene silencing-a three-way. EMBOJ, 1998(17): 4905-4908
99. Richards EJ. DNA methylation and plant development. Trends Genet, 1997(13): 319-323
100.Saze H, Mittelsten SO, Paszkowski J. Maintenance of CpG methylation is essential for epigenetic inheritance during plant gametogenesis. Nature Genetics, 2003(34): 65-69
101.Shi QH, Zhu ZJ, Xu M, Qian QQ, Yu JQ. Effect of excess manganese on the antioxidant system in Cucumis sativus L. under two light intensities. Environ Exp Bot, 2006(58): 197-205
102.Shi QH, Ding F, Wang XF, Wei M. Exogenous nitric oxide protect cucumber roots against oxidative stress induced by salt stress. Plant Physiol Biochem, 2007(45): 542-550
103.Shigeoka S, Ishikawa T, Tamoi M, Miyagawa Y, Takeda T, Yabuta Y, Yoshimura K. Regulation and function of ascorbate peroxidase isoenzymes. J Exp Bot, 2002(53): 1305-1319
104.Shim IS, Momose Y, Yamamoto A, Kim DW, Usui K. Inhibition of catalase activity by oxidative stress and its relationship to salicylic acid accumulation in plants. Plant Growth Regul, 2003(39): 285-292
105.Tan MP. Analysis of DNA methylation of maize in response to osmotic and salt stress based on methylation-sensitive amplified polymorphism. Plant Physiol Biochem, 2010(48): 21-26
106.Thomas CE, McLean LR, Parkar RA, Ohlweiler DF. Ascorbate and phenolic antioxidant interactions in prevention of liposomal oxidation. Lipids, 1992(27): 543-550
107.Wada Y, Miyamoto K, Kusano T, Sano H. Association between up-regulation of stress-responsive genes and hypomethylation of genomic DNA in tobacco plants. Mol Genet Genom, 2004(271): 658-666
108.Wassenegger M. RNA-directed DNA met hylation. Plant Mol Biol, 2000(43): 203-220
109.Xiong LZ, Xu CG, Saghai-Maroof MA, Zhang QF. Patterns of cytosine methylation in an elite rice hybrid and its parental lines by amethylation-sensitive amplification polymorphism technique. Mol Gen Genet, 1999(261): 439-446
110.Xu ML, Li XQ, Korban S. DNA-methylation alterations and exchanges during in vitro cellular differentiation in rose (Rosa hybrida L.). Theor Appl Genet, 2004(109): 899-910
111.Xue T, Hartikainen H, Piironen V. Antioxidative and growth-promoting effect of selenium on senescing lettuce. Plant Soil, 2001(237): 55-61.
112.Wyrwicka A, Sk?odowska M. Influence of repeated acid rain treatment on antioxidative enzyme activities and on lipid peroxidation in cucumber leaves. Environ Exp Bot, 2006(56): 198-204
113.Zhang XY, Yazaki J, Sundaresan A, Cokus S, Chan SW, Chen HM, Henderson IR, Shinn P, Pellegrini M, Jacobsen SE, Ecker JR. Genome-wide high-resolution mapping and functional analysis of DNA methylation in Arabidopsis. Cell, 2006(126): 1189-1201
114.Zhu Z, Wei G, Li J, Qian Q, Yu J. Silicon alleviates salt stress and increases antioxidant enzymes activity in leaves of salt-stressed cucumber (Cucumis sativus L.). Plant Sci, 2004(167): 527-533
2.陈沁,刘友良. GSH对盐胁迫大麦活性氧清除系统的保护作用.作物学报, 2000(26): 365-371
3.龚明,丁念诚,贺子义,刘友良.盐胁迫下大麦和小麦叶片脂质过氧化伤害与超微结构变化的关系.植物学报, 1989(31): 841-846
4.李双顺,林桂珠,林植芳.丙二醛对苋菜叶片光合作用的影响.植物生理学通讯, 1988(3): 41-44
5.李雪林,林忠旭,聂以春,郭小平,张献龙.盐胁迫下棉花基因组DNA表观遗传变化的MSAP分析.作物学报, 2009(35): 588-596
6.廖靖军,安成才,吴思,陈章良.查尔酮合酶基因在植物防御反应中的调控作用.北京大学学报, 2000(36): 566-574
7.潘雅姣,傅彬英,王迪,朱苓华,黎志康.水稻干旱胁迫诱导DNA甲基化时空变化特征分析.中国农业科学, 2009(42): 3009-3018
8.孙国荣,关旸,阎秀峰.盐胁迫对星星草幼苗保护酶系统的影响.草地学报, 2001(9): 34-38
9.王国莉,郭振飞.甲基紫精对水稻不同耐冷品种叶绿素荧光参数的影响.武汉植物学研究, 2008(26): 81-86
10.王素平,郭世荣,李璟.盐胁迫对不同基因型黄瓜幼苗生长的影响.江苏农业科学, 2006(2): 76-79
11.魏国强,朱祝军,方学智. NaCl胁迫对不同品种黄瓜幼苗生长、叶绿素荧光特性和活性氧代谢的影响.中国农业科学, 2004(37): 1754-1759
12.徐志防,罗广华,柯德森.超氧阴离子诱导的叶绿素荧光猝灭.生物化学与生物物理进展, 2002(29): 139-143
13.姚秋菊,张晓伟,赵小忠,魏国强.硅对盐胁迫下黄瓜叶片膜脂过氧化和活性氧清除系统的影响.华北农学报, 2008(23): 109-113
14.杨成丽,刘德立.植物甜蛋白Thaumatin研究进展.武汉植物学研究2001,(19): 153-157
15.杨金兰,柳李旺,龚义勤,黄丹琼,王峰,何玲莉.镐胁迫下萝卜DNA基因组甲基化敏感扩增多态性分析.植物生理与分子生物学学报, 2007(33): 219-226
16.於丙军,刘友良.盐胁迫对一年生盐生野大豆幼苗活性氧代谢的影响.西北植物学报, 2003(23): 18-22
17.张其德.盐胁迫对植物及其光合作用的影响(上).植物杂志, 1999(6), 32-33
18.赵福庚,何龙飞.植物逆境生理生化.北京化工出版社, 2004p55-60
19.郑小梅,伍宁丰. DNA甲基化作用的生物学功能.中国农业科技导报, 2009(11): 33-39
20.宰学明,吴国荣,陆长梅等. Ca2 +对花生幼苗耐热性和活性氧代谢的影响.中国油料作物学报, 2001(23): 46-50
21. Asada K, Takahashi M. Production and scavenging of active oxygen in photosynthesis. In: Kyle DJ, Osmond CB, Arntzen CJ, editors. Photoinhibition. Amsterdam: Elsevier Science, 1987p227-287
22. Asada K.The water-water cycle in chloroplasts: scavenging of active oxygens and dissipation of excess photons. Annu Rev Plant Physiol Plant Mol Biol, 1999(50): 601-639
23. Asada K, Endo T, Mano J, Miyake C. Molecular mechanisms for relaxation of and protection from light stress. In: Satoh K, Murata N (eds) Stress responses of photosynthetic organisms. Elsevier Science BV, 1998p37-52
24. Ananieva EA, Christov KN, Popova LP. Exogenous treatment with salicylic acid leads to increased antioxidant capacity in leaves of barley plants exposed to paraquat. J Plant Physiol, 2004(161): 319-328
25. Azevedo Neto AD, Prisco JT, Enéas-Filho J, Abreu CEB, Gomes-Filho E. Effect of salt stress on antioxidative enzymes and lipid peroxidation in leaves and roots of salt-tolerant and salt-sensitive maize genotypes. Environ Exp Bot, 2006(56): 87-94
26. Aufsatz W, Mette MF, Matzke AJ. et al. The role of MET1 in RNA-directed de novo and maintenance methylation of CG dinucleotides.Plant Molecular Biology, 2004(54): 793-804
27. Bartee L, Malagnac F, Bender J. Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and silencing of an endogenous gene. Genes and Development, 2001(15): 1753-1758
28. Blumwald E, Aharon GS, Apse MP. Sodium transport in plant cells. Biochim Biophys Acta, 2000(1465): 140-151
29. Bernt E, Bergmeyer HU. Inorganic peroxides. In: Bergmeyer HU, editor. Methods of enzymatic analysis. New York: Academic Press, 1974p68-88
30. Bhandal IS, Malik CP. Potassium estimation, uptake, and its role in the physiology and metabolism of flowering plants. lant Physiol. Plant Mol boil, 1992(43): 83-116
31. Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein–dye binding. Anal Biochem, 1976(72): 248-254
32. Boyko A, Kovalchuk I. Epigenetic control of plant stress response. Environ Mol Mutagen, 2008(49): 61-72
33. Bowler C, Montagu MV, Inze D. Superoxide dismutase and stress tolerance. Annu. Rev. Plant Physiol. Plant Mol. Biol, 1992(43): 83-116
34. Cao X, Aufsatz W, Zilberman D. et al. Role of the DRMand CMT3 methyltransferases in RNA-directed DNA methylation. Current Biology, 2003(13): 2212-2217
35. Casano LM, Martín M, Zapata JM, Sabater B. Leaf age- and paraquat concentration-dependent effects on the levels of enzymes protecting against photooxidative stress. Plant Sci, 1999(149): 13-22
36. Cervera MT, Ruiz-García L, Martínez-Zapater JM. Analysis of DNA methylation in Arabidopsis thaliana based on methylation-sensitive AFLP markers. Mol Genet Genomics, 2002(268): 543-552
37. Chagas RM, Silveira JAG, Rafael V, Ribeiro RV, Vitorello VA, Carrer H. Photochemical damage and comparative performance of superoxide dismutase and ascorbate peroxidase in sugarcane leaves exposed toparaquat-induced oxidative stress. Pestic Biochem Physiol, 2008(90): 181-188
38. Chan SW, Henderson IR, and Jacobsen SE. Gardening the genome: DNA methylation in Arabidopsis thaliana. Nat Rev Genet, 2005(6): 351-360
39. Choi SM, Jeong SW, Jeong WJ, Kwon SY, Chow WS, Park YI. Chloro-plast Cu/Zn-superoxide dismutase is a highly sensitive site in cucumber leaves chilled in the light. Planta, 2002(216): 315-324
40. Cramer GR, L?uchli A, Polito VS. Displacement of Ca2+ by Na+ from the plasmalemma of root cells-a primary response to salt stress.Plant Physiology, 1985(79): 207-211
41. Curradi M, Izzo A, Badaracco G., Landsberger N. Molecular mechanisms of gene silencing mediated by DNA methylation. Mol Cell Biol, 2002(22): 3157-3173
42. Dhindsa RS, Plumb-Dhindsa P, Thorpe TA. Leaf senescence: correlated with increase leaves of membrane permeability and lipid peroxidation and decreased levels of superoxide dismutase and catalase. J Exp Bot, 1981(32): 93-101
43. Diaz-Vivancos P, Rubio M, Mesonero V, Periago PM, Ros BarcelóA, Martínez-Gómez P, Hernández JA. The apoplastic antioxidant system in Prunus: response to plum pox virus. J Exp Bot, 2006(57): 3813-3824
44. Djanaguiraman M, Devi DD, Shanker AK, Sheeba JA, Bangarusamy U. Selenium-an antioxidative protectant in soybean during senescence. Plant Soil, 2005(272): 77-86
45. Dyachenko O, Zakharchenko N, Shevchuk T. et al. Effect of hypermethylation of CCWGG sequences in DNA of Mesembryanthemum crystallinum plants on their adaptation to salt stress. Biochemistry (Moscow) 2006(71): 461-465
46. Doulis AG, Debian N, Kingston-Smith AH, Foyer CH. Differential localization of antioxidants in maize leaves. Plant Physiol, 1997(114): 1031-1037
47. Elstner EF, Heupel A. Inhibition of nitrite formation from bydroxylam- moniumchloride: a simple assay for superoxide dismutase. Anal Biochem, 1976(70): 616-620
48. Ekmekci Y, Terzioglu S. Effects of oxidative stress induced by paraquat on wild and cultivated wheats. Pestic Biochem Physiol, 2005(83): 69-81
49. Finnegan EJ, Peacock WJ, Dennis ES. DNA methylation, a key regulator of plant development and other processes. Curr Opin Genet Dev, 2000(10): 217-223
50. Finnegan EJ, Kovac KA. Plant DNA methyltransferases. Plant Molecular Biology, 2000(43): 189-201
51. Flowers TJ, Troke PF, Yeo AR. The mechanism of salt tolerance in halophytes. Annu Rev Plant Physiol, 1977(28): 89-121
52. Foyer CH, Descourvieres P, Kunert KJ. Protection against oxygen radicals: an important defence mechanism studied in transgenic plants. Plant Cell Environ, 1994(17): 507-523
53. Foyer CH, Halliwell B. The presence of glutathione and glutathione reductase in chloroplasts: A proposal role in ascorbic acid metabolism. Planta, 1976(133): 21-25
54. Foyer CH, Lopez-Delgado H, Dat JF, Scott IM. Hydrogen peroxide and glutathione-associated mechanisms of acclamatory stress tolerance and signaling. Physiol Plant, 1997(100): 241-254
55. Ge CL, Yang XY, Liu XN, Sun JH, Luo S, Wang ZG. Effect of heavy metal on levels of methylation in DNA of rice and wheat. J Plant Physiol Mol Biol, 2002(28): 363-368
56. Gong HJ, Chen M, Chen GC. et al. Effects of silicon on growth of wheat under drought. Plant Nutr, 2003(26): 1055-1063
57. Gonzalgo ML, Liang GN. Identification and characterization of differentially methylated regions of genomic DNA by methylation-sensitive arbitrarily primed PCR. Cancer Res, 1997(57): 594-599
58. Gossett DR, Banks SW, Millhollon EP, Lucas MC. Antioxidant response to NaCl stress in a control and a NaCl-tolerant cotton cell line grown in the presence of paraquat, buthionine sulfoximine and exogenous glutathione. Plant Physiol, 1996(112): 803-809
59. Hai P, Jing Z. Plant genomic DNA methylation in response to stresses: Potential applications and challenges in plant breeding. Progress in Natural Science, 2009(19): 1037–1045
60. Hoque MA, Banu MNA, Okuma E, Amako K, Nakamura Y, Shimoishi Y, Murata Y. Exogenous proline and glycinebetaine increase NaCl-induced ascorbate-glutathione cycle enzyme activities, and proline improves salt tolerance more than glycinebetaine in tobacco Bright Yellow-2 suspension-cultured cells. J Plant Physiol, 2007(164): 1457-1468
61. Howell C, Bestor T, Ding F. et al. Genomic imprinting disrupted by a maternal effect mutation in the Dnmt1 gene. Cell, 2001(104): 829-838
62. Hwang SY, Lin HW, Chern RH, Lo HF, Li L. Reduced susceptibility to water logging together with high-light stress is related to increases in superoxide dismutase and catalase activities in sweet potato. Plant Growth Regul, 1999( 27): 167-172
63. Janda T, Szalai G, Antunovics Z, Horváth E, Páldi E. Effect of benzoic acid and aspirin on chilling tolerance and photosynthesis in young maize plants. Maydica, 2000(45): 29-33
64. Jaenisch R. DNA methylation and imprinting: why bother? Trends Genet, 1997(13): 323-329
65. Jones PA, Takai D. The role of DNA methylation in mammalian ep igenetics. Science, 2001(293): 1068-1070
66. Kampfenkel K, Montagu MV, Inze D. Extraction and determination of ascorbate and dehydroascorbate from plant tissue. Anal Biochem, 1995(225):165-167
67. Kankel M, Ramsey D, Stokes T. et al. Arabidopsis MET1 cytosine methyltransferase mutants. Genetics, 2003 (163): 1109-1122
68. Kovarik A, Koukalova B, Bezdek M. et al. Hypermethylation of tobacco heterochromatic loci in response to osmotic stress. Theor Appl Genet, 1997(95): 301-306
69. Labra M, Ghiani A, Citterio S. et al. Analysis of cytosine methylation pattern in response to water deficit in pea root tips. Plant Biol, 2002(4): 694-699
70. Lee DH, Kim YS, Lee CB. The inductive responses of the antioxidant enzymes by salt stress in the rice (Oryza sativa L.). J Plant Physiol , 2001(158): 737-745
71. Li X Q, Xu M L, Korban S S. DNA methylation profiles differ between field- and in vitro-grown leaves of apple. Journal of Plant Physiology, 2002(159): 1229-1234
72. Liang YC. Eeffcts of silicon on enzyme activiy and sodium,Potassium and calcium concentration in barely under saltstress. Palnt and soil, 1999(29): 217-224
73. Liang YC, Hu F, Yang MC. et al. Antioxidative defenses and water deficit-induced oxidative damage in rice (Oryza sativa L.) growing on non-flooded paddy soils with ground mulching. Plant and Soil, 2003(257): 407-416
74. Liang YC, Chen Q, Liu Q. et al. Exogenous silicon (Si) increases antioxidant enzyme activity and reduces lipid peroxidation in roots of salt-stressed barley (Hordeum vulgare L.). Journal of Plant Physiology, 2003(160): 1157-1164
75. Liau YJ, Wen L, Shaw JF, Lin CT. A highly stable cambialistic-superoxide dismutase from Antrodia camphorata: expression in yeast and enzyme properties. J Biotechnol, 2007(131): 84-91
76. Lindroth A, Cao X, Jackson J. et al. Requirement of CHROMOMETHYLASE3 for maintenance of CpXpG methylation. Science, 2001(292): 2077-2080
77. Luster DG, Donaldson RP. Orientation of electron transport activities inthe membrane of intact glyoxysomes isolated from castor bean endosperm. Plant Physiol, 1987(85): 796-800
78. Mcclelland M, Nelson M, Raschke E. Effect of site-specific modification on restriction endonucleases and DNA modification methyltransferases. Nucleic Acids Research, 1994(22): 3640-3459
79. Martinez CA, Loureiro ME, Oliva MA, Maestri M. Differential responses of superoxide dismutase in freezing resistant Solanum curtilobum and freezing sensitive Solanum tuberosum subjected to oxidative and water stress. Plant Science, 2001(160): 505-551
80. Matzke M, Aufsatz W, Kanno T. et al. Genetic analysis of RNA-mediated transcriptional gene silencing. Biochimica et Biophysica Acta, 2004(1677): 129-141
81. Mascher R, Lippmann B, Holzinger S, Bergmann H. Arsenate toxicity: effects on oxidative stress response molecules and enzymes in red clover plants. Plant Sci, 2002(163): 961-969
82. Meyer P, Saedler H. Homology-dependent gene silencing in plants. A nnu. Rev. Plant Physiol. Plant Mol Biol, 1996(47): 23-48
83. Mittler, R. Oxidative stress, antioxidants and stress tolerance. Trends Plant Sci, 2002(7): 405-410
84. Munns R. Comparative physiology of salt and water stress. Plant Cell Environ, 2002(28): 239-250
85. Molina A, Bueno P, Marin MC, Rodriguez-Rosales MP, Belver A, Venema K, Donaire JP. Involvement of endogenous salicylic acidcontent, lipoxygenase and antioxidant enzyme activities in the response of tomato cell suspension cultures to NaCl. New Phytol, 2002(156): 409-415
86. M?ller IM. Plant mitochondria and oxidative stress: electron transport, NADPH turnover, and metabolism of reactive oxygen species. Annu Rev Plant Physiol Plant Mol Biol, 2001(52): 561-591
87. Neill S, Desikan R, Hancock J. Hydrogen peroxide signaling. Curr Opin Plant Biol, 2002(5): 388-395
88. Newell-Price J, Clark AJ, King P. DNA methylation and silencing of gene expression. Trends Endocrinol Metab, 2000(11): 142-148
89. Noctor G, Foyer CH. Ascorbate and glutathione: keeping active oxygen under control. Annu.Rev. Plant Physiol. Plant Mol Biol, 1998(49): 249-79
90. Okano M, Bell D, Haber D. et al. DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development. Cell, 1999 (99): 247-257
91. Ohkawa H, Ohishi N, Yagi K. Assay for lipid peroxides in animal tissue by thiobarbituric acid reaction. Anal Biochem, 1979(95): 351-358
92. Rassoulzadegan M, Grandjean V, Gounon P, Vincent S, Gillot I, Cuzin F. RNA-mediated non-mendelian inheritance of an epigenetic change in the mouse. Nature, 2006(441): 469-474
93. Pelissier T, Thalmeir S, Kempe D. et al. Heavy de novo methylation at symmetrical and non- symmetrical sites is a hallmark of RNA-directed DNA methylation. Nucleic Acids Research, 1999(27): 1625-1634
94. Pereira GJG, Molina SMG, Lea PJ, Azevedo RA. Activity of antioxidant enzymes in response to cadmium in Crotalaria juncea. Plant Soil, 2002(239): 123-132
95. Perelman A, Dubinsky Z, Martínez R. Temperature dependence of superoxide dismutase activity in plankton. J Exp Mar Biol Ecol, 2006(334): 229-235
96. Portis E, Acquadro A, Comino C, Lanteri S. Analysis of DNA methylation during germination of pepper (Capsicum annuum L.) seeds using methylation-sensitive amplification polymorphism (MSAP). Plant Sci, 2004(166): 169-178
97. Ramiro DA, Guerreiro-Filho O, Mazzafera P. Phenol contents, oxidase activities, and the resistance of coffee to the leaf miner Leucoptera coffeella. J Chem Ecol, 2006(32): 1977-1988
98. Razin A. CpG methylation, chromatin structure and gene silencing-a three-way. EMBOJ, 1998(17): 4905-4908
99. Richards EJ. DNA methylation and plant development. Trends Genet, 1997(13): 319-323
100.Saze H, Mittelsten SO, Paszkowski J. Maintenance of CpG methylation is essential for epigenetic inheritance during plant gametogenesis. Nature Genetics, 2003(34): 65-69
101.Shi QH, Zhu ZJ, Xu M, Qian QQ, Yu JQ. Effect of excess manganese on the antioxidant system in Cucumis sativus L. under two light intensities. Environ Exp Bot, 2006(58): 197-205
102.Shi QH, Ding F, Wang XF, Wei M. Exogenous nitric oxide protect cucumber roots against oxidative stress induced by salt stress. Plant Physiol Biochem, 2007(45): 542-550
103.Shigeoka S, Ishikawa T, Tamoi M, Miyagawa Y, Takeda T, Yabuta Y, Yoshimura K. Regulation and function of ascorbate peroxidase isoenzymes. J Exp Bot, 2002(53): 1305-1319
104.Shim IS, Momose Y, Yamamoto A, Kim DW, Usui K. Inhibition of catalase activity by oxidative stress and its relationship to salicylic acid accumulation in plants. Plant Growth Regul, 2003(39): 285-292
105.Tan MP. Analysis of DNA methylation of maize in response to osmotic and salt stress based on methylation-sensitive amplified polymorphism. Plant Physiol Biochem, 2010(48): 21-26
106.Thomas CE, McLean LR, Parkar RA, Ohlweiler DF. Ascorbate and phenolic antioxidant interactions in prevention of liposomal oxidation. Lipids, 1992(27): 543-550
107.Wada Y, Miyamoto K, Kusano T, Sano H. Association between up-regulation of stress-responsive genes and hypomethylation of genomic DNA in tobacco plants. Mol Genet Genom, 2004(271): 658-666
108.Wassenegger M. RNA-directed DNA met hylation. Plant Mol Biol, 2000(43): 203-220
109.Xiong LZ, Xu CG, Saghai-Maroof MA, Zhang QF. Patterns of cytosine methylation in an elite rice hybrid and its parental lines by amethylation-sensitive amplification polymorphism technique. Mol Gen Genet, 1999(261): 439-446
110.Xu ML, Li XQ, Korban S. DNA-methylation alterations and exchanges during in vitro cellular differentiation in rose (Rosa hybrida L.). Theor Appl Genet, 2004(109): 899-910
111.Xue T, Hartikainen H, Piironen V. Antioxidative and growth-promoting effect of selenium on senescing lettuce. Plant Soil, 2001(237): 55-61.
112.Wyrwicka A, Sk?odowska M. Influence of repeated acid rain treatment on antioxidative enzyme activities and on lipid peroxidation in cucumber leaves. Environ Exp Bot, 2006(56): 198-204
113.Zhang XY, Yazaki J, Sundaresan A, Cokus S, Chan SW, Chen HM, Henderson IR, Shinn P, Pellegrini M, Jacobsen SE, Ecker JR. Genome-wide high-resolution mapping and functional analysis of DNA methylation in Arabidopsis. Cell, 2006(126): 1189-1201
114.Zhu Z, Wei G, Li J, Qian Q, Yu J. Silicon alleviates salt stress and increases antioxidant enzymes activity in leaves of salt-stressed cucumber (Cucumis sativus L.). Plant Sci, 2004(167): 527-533