甜菜碱对NaCl胁迫下小麦细胞保护酶活性的影响

本文以小麦为材料,研究甜菜碱对NaCl胁迫下小麦幼苗细胞保护酶系统的影响。结果表明,外源甜菜碱能够提高NaCl胁迫下小麦幼苗超氧化物歧化酶、过氧化物酶等细胞保护酶的活性,抑制过氧化作用产物丙二醛的积累,降低叶片质膜透性和盐害对细胞膜的伤害。所有这些变化都有利于提高NaCl胁迫下小麦幼苗细胞膜的稳定性、完整性和对NaCl胁迫的适应性。     

盐分胁迫条件下甜菜碱对小麦幼苗体内Na+、K+和Cl-的含量及其分布的影响

以抗盐品种茶淀红和盐敏感品种中国春等两种小麦为实验材料,研究甜菜碱对盐分胁迫条件下小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）幼苗Ｎａ＋、Ｋ＋、Ｃｌ－的吸收、分配的影响。结果表明：外源甜菜碱能够在一定程度上限制幼苗对Ｎａ＋、Ｃｌ－的吸收,阻滞其向地上部分运输的数量和速度,同时提高体内Ｋ＋含量、向上运输效率,降低地上部分对Ｎａ＋、Ｋ＋的选择性（ＳＮａ＋、Ｋ＋）,从而提高小麦幼苗抗盐性和对盐分胁迫的适应性。     

盐分胁迫条件下甜菜碱对小麦幼苗体内Na^＋,K^＋和Cl^—的含量及 …

以抗盐品种茶淀红和盐敏感品种中国春等两种小麦为实验材料,研究甜菜碱对盐分胁迫条件下小麦幼苗Ｎａ＾＋、Ｋ＾＋、Ｃｌ＾－的吸收、分配的影响。结果表明：外源甜菜碱能够在一定程度上限制幼苗对Ｎａ＾＋、Ｋ＾＋、Ｃｌ＾－的吸收、分配的影响。结果表明：外源甜菜碱能够在一定程度上限制幼苗对Ｎａ＾＋、Ｃｌ＾－的吸收,阻滞其向地上部分运输的数量和速度,同时提高体内Ｋ＾＋含量、向上运输效率,降低地上部分对Ｎａ＾＋、Ｋ＾     

外源甜菜碱对盐胁迫一科幼苗体内几种与抗逆能力有关物质含 …

外源甜菜碱能提高ＮａＣｌ胁迫下小麦幼苗体内游离脯氨酸、可溶性糖和可溶性蛋白质等物质的含量,限制幼苗根系对Ｎａ＾＋的吸收,并阻滞其向地上部分的运输,提高体内Ｋ＾＋含量及其向上的运输。     

水杨酸和阿斯匹林对小麦盐害的缓解作用

盐胁迫条件下水杨酸和阿斯匹林能提高小麦种子发芽率、发芽指数和活力指数,降低幼苗叶片质膜透性和盐胁迫对细胞膜的伤害,提高幼苗体内超氧化物歧化酶、过氧化物酶等细胞保护酶的活性,减少膜脂过氧化作用产物丙二醛的积累,降低根系Ｎａ＋和提高根系Ｋ＋ 的向上运输选择性。所有这些变化都有利于缓解盐胁迫对小麦的伤害,提高其对盐胁迫的适应性。     

水杨酸和阿斯匹林对小麦盐害的缓解作用

盐胁迫条件下水杨酸和阿斯匹林能提高小麦种子发芽率、发芽指数和活力指数,降低幼苗叶片质膜透性和盐胁迫对细胞膜的伤害,提高幼苗体内超氧化物歧化酶、过氧化物酶等细胞保护酶的活性,减少膜脂过氧化作用产物丙二醛的积累,降低根系Ｎａ＾＋和提高根系Ｋ＾＋的向上运输选择性。所有这些变化都有利于缓解盐胁迫对小麦的伤害,提高其对盐胁迫的适应性。     

水杨酸和阿斯匹林对小麦幼苗生长过程中盐害的缓解作用

以小麦为材料,研究盐分胁迫对小麦幼苗生长的影响以及水杨酸和阿斯匹林对小麦幼苗生长过程中盐害的缓解作用。结果表明,水杨酸和阿斯匹林能够相对提高盐分胁迫条件下小麦幼苗叶片的相对含水量,降低叶片质膜透性和盐害对细胞膜的伤害,提高幼苗体内超氧化物歧化酶、过氧化物酶等细胞保护酶的活性,抑制过氧化作用产物丙二醛的积累;同时发现外源水杨酸和阿斯匹林还能够提高幼苗体内ＡＴＰ的含量,维持幼苗能量代谢和供应的正常进行,从而提高小麦对盐分胁迫的适应性     

等渗NaCl和KCl胁迫对高粱幼苗生长和气体交换的影响

本文比较研究了等渗ＮａＣｌ和ＫＣｌ胁迫下,高粱幼苗生长及叶片离子含量、质膜相对透性和有关气体交换参数的变化。结果表明,在低浓度ＮａＣｌ和ＫＣｌ胁迫７天时,高粱生长、含水量和质膜相对透性与对照相比没有明显变化,而净光合速率、蒸腾速率和气孔导度已明显下降,叶肉细胞间隙ＣＯ２浓度明显增加。ＮａＣｌ胁迫下叶片Ｎａ＋含量成倍增加,而Ｋ＋和Ｃａ２＋含量无明显变化。ＫＣｌ胁迫时叶片Ｋ＋含量明显增加,Ｃａ２＋含量明显下降,而Ｎａ＋含量没有明显变化。随着ＮａＣｌ或ＫＣｌ浓度的增加,幼苗生长和叶片含水量明显下降,质膜透性和细胞间隙ＣＯ２浓度明显增加,净光合速率、蒸腾速率和气孔导度进一步下降。ＮａＣｌ胁迫下叶片Ｎａ＋含量进一步增加,Ｋ＋和Ｃａ２＋进一步下降,而ＫＣｌ胁迫下叶片Ｋ＋含量进一步增加,Ｎａ＋和Ｃａ２＋含量进一步下降。ＫＣｌ对高粱生长抑制、质膜透性、Ｃａ２＋含量下降及光合气体交换参数的影响均明显大于等渗的ＮａＣｌ。     

NaCl对水稻谷氨酸合酶和谷氨酸脱氢酶的胁迫作用

在ＮａＣｌ的胁迫下,水稻幼苗根和叶的谷氨酸合酶和谷氨酸脱氢酶的活性随着营养液中的ＮａＣｌ浓度的升高而降低;游离ＮＨ４＾＋在叶中积累,在根中未见明显变化。与根相比,叶对ＮａＣｌ的胁迫作用更为敏感。叶的ＮＡＤＨ－ＧＯＧＡＴ和ＮＡＤＨ－ＧＤＨ活性在ＮａＣｌ胁迫降低的程度明显大于根。无论是否有ＮａＣｌ存在,根的ＮＡＤＨ－ＧＤＨ活性明显高于叶。ＧＳ／ＧＤＨ比值分析提示,对对照下,根中的ＮＨ４＾存在,根的ＮＡ     

碳酸钠逐级驯化对星星草幼苗抗碱性的影响

对不同浓度Ｎａ２ＣＯ３膛级驯化星星草幼苗的研究结果表明,逐级提高对星星草幼苗的盐碱胁迫强度,在一定程度上可以缓解Ｎａ２ＣＯ３对幼苗鲜重和干重增长的抑制作用,及其对星星草幼苗细胞膜的伤害,从而提高幼苗对Ｎａ２ＣＯ３胁迫的抗性。并就星星草幼苗耐盐碱的极限进行了讨论。     

外源NO对NaCl胁迫下辣椒幼苗氧化损伤的保护效应

以辣椒品种陇椒2号为试验材料,研究了外源NO供体硝普钠(SNP)对辣椒幼苗氧化损伤的影响.结果显示,在100 mmol/L NaCl胁迫下,辣椒叶片的MDA含量、质膜相对透性和脯氨酸含量均增加,保护酶SOD、CAT活性降低,而POD活性只在胁迫18 d时降低.0.1 mmol/L SNP处理可减缓NaCl胁迫下辣椒幼苗叶片MDA含量的上升,降低叶片质膜相对透性,并诱导SOD、POD和CAT活性增加,提高脯氨酸含量,表明外源NO可以通过提高盐胁迫下辣椒幼苗叶片组织的抗氧化能力来缓解氧化损伤.而SNP相似物NaNO2和K3Fe(CN)6处理对盐胁迫引起的氧化损伤并没有起到明显的缓解作用,进一步证实了NO对辣椒幼苗耐盐性具有专一性的调节作用.     

Antioxidant defense system,lipid peroxidation,proline-metabolizing enzymes,and biochemical activities in two <Emphasis Type="Italic">Morus alba</Emphasis> genotypes subjected to NaCl stress

Salt stress-induced changes in antioxidant enzymes, lipid peroxidation, proline and glycine betaine contents, and proline-metabolizing enzymes were examined in the leaves of two mulberry cultivars (Local and Sujanpuri). With increasing salinity up to 150 mM NaCl, superoxide dismutase, catalase, ascor-bate peroxidase, guaiacol peroxidase, glutathione reductase, and monodehydroascorbate reductase activities were increased in both cultivars as compared to control, but more pronounced increase was observed in cv. Local. Salt stress enhanced the rate of lipid peroxidation (as indicated by increasing MDA content) in both cultivars. Under NaCl stress, cv. Local showed less change in the MDA content than cv. Sujanpuri. Salt stress resulted in a significant accumulation of free proline in mulberry leaves, and more accumulation was detected in cv. Local than cv. Sujanpuri. The leaves of cv. Local showed 9-fold accumulation of glycine betaine in comparision with cv. Sujanpuri after 20 days at 150 mM NaCl. A decrease in proline oxidase activity and an increase in γ-glutamyl kinase activity were observed with increasing NaClconcentration. The relative water content and electrolyte leakage also decreased after increasing the NaCl concentration, but a decrease was more pronounced in cv. Sujanpuri than in cv. Local. The results indicate that oxidative stress may play an important role in salt-stressed mulberry plants and cv. Local have more efficient antioxidant characteristics, which could provide for a better protection against oxidative stress.     

甜菜碱对呼吸酶的保护效应

以菠菜（Ｓｐｉｎａｃｉａ ｏｌｅｒａｃｅａ Ｌ．）叶片为材料,研究了不同浓度的甜菜碱和ＮａＣｌ对三羧酸循环、末端氧化和光呼吸的组成酶的活性的影响。与电解质ＮａＣｌ不同,高浓度的甜菜碱对这些酶的活性是非抑制性的,并对ＮａＣｌ的抑制作用有一定保护效应。甜菜碱是很好的有机渗透调节剂。这与甜菜碱在细胞质中起渗透调节作用,以及是无机渗透调节剂的配伍溶质的假设是一致的。     

Methylglyoxal as a novel signal molecule induces the salt tolerance of wheat by regulating the glyoxalase system,the antioxidant system,and osmolytes

Reactive carbonyl species methylglyoxal (MG) has always been regarded as a cytotoxic metabolite, but now is emerging to function as signal molecule in plants. However, whether MG can induce salt tolerance is elusive. In this study, treatment of wheat seeds with NaCl reduced seed germination, plant height, root length, fresh weight, and dry weight, indicating the inhibitive effects of NaCl on seed germination and seedling growth. The inhibitive effects of NaCl were alleviated by applying exogenous MG, but aggravated by the MG scavenger N-acetyl-L-cysteine (NAC), suggesting that MG could induce the salt tolerance of wheat. In addition, MG increased glyoxalase I and glyoxalase II activities and decreased endogenous MG content in wheat seedlings under NaCl stress, whereas coapplication of NAC weakened glyoxalase activity and enhanced the endogenous MG level. Also, MG activated superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase activities; increased glutathione and ascorbic acid levels; and decreased superoxide radical production and H₂O₂ and malondialdehyde contents under NaCl stress, while NAC reversed these physiological parameters. Furthermore, MG also induced the accumulation of proline, glycine betaine, and soluble sugar under NaCl stress, whereas this accumulation was weakened by NAC. This work reported for the first time that MG could induce the salt tolerance of wheat, and the acquisition of this salt tolerance was involved in the activation of the glyoxalase system and antioxidant system, as well as the accumulation of osmolytes.     

Differential Responses of Two Wheat Varieties Differing in Salt Tolerance to the Combined Stress of Mn and Salinity

The effect of Mn and NaCl on growth, mineral nutrients and antioxidative enzymes in two tetroploid wheat genotypes differing in salt tolerance was investigated in this study. 100 mM NaCl and Mn stress significantly inhibited plant growth, photosynthesis and Ca uptake, while stimulated ROS accumulation, MDA and proline content in wheat plants, Mn stress also increased SOD, APX, GR and DHAR activities. Durum wheat (AS780) was less affected by 100 mM NaCl and Mn stress than emmer wheat (AS847) due to more proline production, higher antioxidative enzymes activities and less-affected mineral nutrients. Application of 10 mM NaCl to Mn-stressed durum wheat alleviated Mn-induced damage by reducing Mn accumulation and translocation, while promoting proline accumulation and SOD, APX and GR activities. Irrespective of NaCl level, the combined stress of Mn and NaCl caused more severe oxidative stress, result in further reduction of photosynthetic rate and plant growth in emmer wheat as compared to Mn stress alone. The additively negative effects of NaCl and Mn stress on growth of emmer wheat results from reduced SOD and APX activities as well as Ca, Cu and Fe accumulation in both shoots and roots. These results suggest that salt-tolerant durum wheat is superior to emmer in adapting to Mn stress and the combined stress of salinity and Mn.

     

Overaccumulation of glycine betaine enhances tolerance of the photosynthetic apparatus to drought and heat stress in wheat

To investigate the role of glycine betaine in photosynthesis under stress, a transgenic wheat (Triticum aestivum L.) line T6 overaccumulating glycine betaine and its wild type Shi4185 were used. Seedlings were exposed to conditions of drought (30%, PEG-6000), heat (40°C) and their combination. The results revealed ultrastructural damage to the chloroplast and thylakoid lamellae with the withered phenotype by both drought and heat stress, and the damage was exacerbated by the combination of drought and heat. The appearance of a K step in the typical O-J-I-P curve and the decrease of Hill activity indicated a reduction of oxygen evolving complex function caused by stress. The greater damage was found in wild type than T6. Overaccumulation of glycine betaine in T6 could protect lipids in the thylakoid membrane from damage and stabilize the index of unsaturated fatty acids under stress. A lower ratio of monogalactosyl diacylglycerol/digalactosyl diacylglycerol and higher phosphatidylglycerol content in the thylakoid membrane of T6 were also observed under stress. These effects can promote stability of the thylakoid membrane. Otherwise, glycine betaine overaccumulation decreased photoinhibition of PSII under stress. The results also suggest that xanthophyll cycle-dependent non-radiative energy dissipation may be involved in the GB-mediated effects on PSII function under stress conditions.     

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

Up-regulation of the antioxidant system provides protection against NaCl-induced oxidative damage in plants. Antioxidants and activity of enzymes involved in the ascorbate-glutathione (ASC-GSH) cycle in tobacco Bright Yellow-2 (BY-2) were investigated to assess the antioxidant protection offered by exogenous proline and glycinebetaine (betaine from now on) against salt stress using cells grown in suspension culture. Reduced ascorbate (ASC) was detected in BY-2 cells but dehydroascorbate (DHA) was not. Large quantities of a reduced form of glutathione (GSH) and smaller quantities of an oxidized form of glutathione (GSSG) were detected in BY-2 cells. Salt stress significantly reduced the contents of ASC and GSH as well as activities of ASC-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Exogenous proline or betaine increased the activities of all enzymes except MDHAR involved in NaCl-induced ASC-GSH cycle. Levels of ASC and GSH in BY-2 cells under salt stress were lower in the presence of proline or betaine than in the absence of proline or betaine whereas there was no difference in redox status. Proline proved more effective than betaine in maintaining the activity of enzymes involved in NaCl-induced ASC-GSH cycle. Neither proline nor betaine had any direct protective effect on NaCl-induced enzyme activity involved in the antioxidant system; however, both improved salt tolerance by increasing enzyme activity. The present study, together with our earlier findings [Hoque MA, Okuma E, Banu MNA, Nakamura Y, Shimoishi Y, Murata Y. Exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine by increasing antioxidant enzyme activities. J Plant Physiol 2006;164:553-61.], suggests that proline offered greater protection against salt stress than betaine did because proline was more effective in increasing the activity of enzymes involved in the antioxidant system.