NaCl胁迫对甘薯叶片叶绿体超微结构及一些酶活性的影响

随ＮａＣｌ胁迫浓度的提高,甘薯叶片叶绿体数目逐渐减少,类囊体膜片层松散、扭曲、破裂及逐渐解体膜片层检叶绿素含量下降。与此同时,Ｈ２Ｏ２、ＭＤＡ含量增加,ＡＳＰ、ＳＯＤ活性表现先上升后下降的趋势。耐盐品种在ＮａＣｌ胁迫下能维持较强的Ｈ２Ｏ２清除能力和较低的ＭＤＡ水平。     

外源亚精胺对NaCl胁迫下毕氏海蓬子光合参数和叶绿体超微结构的影响

在0、100、300、500和700 mmol·L-1NaCl胁迫条件下比较了喷施0.1mmol·L-1亚精胺(Spd)对毕氏海蓬子(Salicomia bigelovii Torr.)幼苗叶绿素含量、净光合速率、气孔导度、胞间CO2浓度和叶绿体超微结构的影响.结果表明:毕氏海蓬子的叶绿素含量、净光合速率和气孔导度均呈低浓度条件下(0、100和300 mmol·L-1NaCl)升高、高浓度条件下(500和700 mmol·L-1NaCl)降低的趋势,在300 mmol·L-1 NaCl胁迫条件下达到最高值:胞间CO2浓度则呈低浓度NaCl胁迫条件下降低、500 mmol·L-1NaCl条件下升高、700 mmol·L-1NaCl条件下略降低的趋势;在0～500 mmol·L-1NaCl胁迫条件下叶绿素a/b值变化不明显,但在700 mmol·L-1NaCl条件下急剧降低.在低浓度NaCl胁迫条件下,叶绿体整体膨胀,类囊体片层结构松散,但叶绿体和类囊体结构仍保持完整;而经500和700mmol·L-1NaCl处理后,叶绿体超微结构被严重破坏,叶绿体膜结构破裂、类囊体结构松散呈放射状、有些叶绿体完全解体.而在相应的NaCl胁迫条件下喷施0.1 mmol·L-1Spd,毕氏海蓬子的叶绿素含量、净光合速率、气孔导度和胞间CO2浓度虽然也呈现出相同的变化趋势,但其数值均显著高于对照(未喷施Spd);且叶绿体超微结构的损伤程度也轻于对照.研究结果说明:喷施外源Spd能够减缓NaCl胁迫对毕氏海蓬子的伤害作用.     

等渗NaCl、干旱胁迫对番茄幼苗光合特性及叶绿体超微结构的影响

为分析等渗盐分和水分胁迫对番茄叶片光合功能的影响,选用耐盐性不同的4种基因型番茄(小果型的辽园红玛瑙、野生醋栗番茄、大果型的金田粉冠、超402)进行等渗的140 mmol·L^-1NaCl和15%PEG6000模拟盐分和水分胁迫.结果表明: 在光合特性方面,处理12 d后,两种胁迫导致4种不同基因型番茄的叶绿素含量(叶绿素a、叶绿素b、叶绿素总量)、光合速率、气孔导度、胞间CO₂浓度、蒸腾效率降低,气孔限制值升高.两种胁迫导致的光合下降由气孔性因素所致.等渗的盐分胁迫对番茄的光合系统损伤大于水分胁迫,这是因为盐分胁迫除了渗透胁迫还会导致离子伤害.4种不同基因型番茄中,耐盐型的辽园红玛瑙具有高光合特性,金田粉冠光合效率最差.在叶绿体超微结构方面,两种胁迫会造成番茄叶片的气孔密度增加,气孔张开率降低,叶绿体长度增加,宽度变小,长宽比增大,叶绿体内基粒数减少,嗜锇颗粒数增多.盐分胁迫下两种番茄叶绿体结构的影响大于水分胁迫,耐盐种醋栗番茄气孔变化小于盐敏感品种金田粉冠.     

NaCl胁迫对宁夏枸杞叶和幼根显微及超微结构的影响

以宁夏枸杞为材料,采用超薄切片技术制备样品,应用光学显微镜和透射电镜分析了不同浓度NaCl胁迫条件下宁夏枸杞叶和幼根显微及超微结构的变化.结果表明:随着NaCl胁迫的加重,(1)叶片上表皮细胞增厚,栅栏组织细胞出现缩短现象,排列疏松且紊乱;幼根的初生结构无明显变化.(2)叶片栅栏组织中叶绿体不再紧靠在细胞膜上,叶绿体双...     

NaCl胁迫对5个引自北美的树种叶肉细胞超微结构的影响

为明确美国白蜡(Fraxinus americana L.)、茶条槭(Aceginnala Maxim.)、红桤木(Alnus rubra Bong.)、水紫树(Nyssa aquatica L.)和美国皂荚(Gleditsia triacanthos L.)5个引自北美的树种的耐盐性,采用水培方法、利用透射电镜技术对0(对照)、4和8 g·L-1 NaCl胁迫处理后5个树种1年生苗叶肉细胞超微结构的变化进行了观察和比较.观察结果表明:正常条件(0g·L-1NaCl)下,5个树种叶肉细胞在叶绿体形态、嗜锇颗粒数量等方面略有差异,但均未发生质壁分离现象.经NaCl胁迫处理后,5个树种叶肉细胞中的叶绿体和细胞核受到不同程度的损伤,表现为叶绿体膜消失,类囊体片层结构肿胀,叶绿体降解,嗜锇颗粒增大或增多,细胞核的核膜消失、核染色质凝聚;且随NaCl质量浓度的提高,损伤程度均逐渐加剧.4和8g·L-1NaC1胁迫条件下,美国皂荚、茶条槭和水紫树的叶肉细胞发生质壁分离现象,而红桤木、美国白蜡和水紫树的叶肉细胞内出现环状片层.根据观察结果,推测红桤木和美国白蜡对NaCl胁迫的耐性较强,美国皂荚和茶条槭也有一定的耐性,而水紫树的耐性最弱.     

NaCl胁迫对5个桂花品种叶片超微结构的影响

该研究以5个桂花品种为材料,以Hoagland培养液为对照,设计2个NaCl含量(70、100 mmol/L)处理10 d后利用透射电镜和扫描电镜观察各处理不同品种的叶片超微结构特征,以明确桂花品种对耐NaCl胁迫的解剖结构响应机制。结果显示：(1)透射电镜观察发现：随NaCl 胁迫程度的加强,5个桂花品种叶肉细胞中叶绿体结构受到不同程度地破坏;70 mmol/L NaCl处理后,5个品种的细胞核基本保持正常,而100 mmol/L NaCl处理后核内染色质发生降解;随着NaCl胁迫程度的加强,5个桂花品种的类囊体片层结构中嗜锇颗粒明显增多;在膜结构方面,大叶银桂的叶肉细胞被破坏程度最为严重,叶绿体膜被破坏,叶绿体形状基本不能辨认。(2)扫描电镜观察结果显示：随着NaCl浓度的增大,5个品种叶片表面的气孔密度不断增大,而张开气孔的密度却不断减小,且叶肉细胞体积均缩小;‘大叶银桂’、‘笑秋风’、‘晚籽银桂’的栅栏组织占叶厚的比重随NaCl胁迫浓度的增大而升高,‘潢川金桂’和‘紫梗籽银桂’的栅栏组织占叶厚的比重则随NaCl胁迫浓度的增大而呈先升高后降低的趋势。研究表明,NaCl胁迫对桂花叶片细胞叶绿体、细胞核等的超微结构会造成损伤,且NaCl胁迫浓度越高损伤越明显。该试验可初步判断‘大叶银桂’、‘笑秋风’、‘晚籽银桂’的耐盐性略高于‘潢川金桂’和‘紫梗籽银桂’。     

干旱胁迫对5种植物叶绿体和线粒体超微结构的影响

应用温室盆栽方法,研究了土壤干旱胁迫对麻栎（Quercus acutissima Carruth）、黄檀（Dalbergia hupeana Hance）、黄连木(Pistacia chinensis)、湿地松（Pinus elliottii）、朴树（Celtis sinesis Pers）5个树种叶肉细胞超微构的影响。结果表明：正常水分条件下,叶肉细胞中各细胞器结构完整。轻度干旱胁迫下,湿地松的叶片超微结构未受损伤。麻栎线粒体无明显变化,叶绿体有扩张现象。黄连木与黄檀线粒体外膜有降解现象,叶绿体膨胀。朴树线粒体与叶绿体受损明显。重度胁迫下,湿地松和麻栎的线粒体内部出现降解,叶绿体受损。黄连木与黄檀出现质壁分离,叶绿体与线粒体受到严重损伤。朴树细胞内部受损最严重。可将5个树种分为3种不同的抗旱等级：湿地松与麻栎抗旱性较强,黄连木与黄檀抗旱性中等,朴树抗旱性较弱。     

盐胁迫对扁桃光合特性和叶绿体超微结构的影响

温室条件下,分别用浓度为150、300、350 mmol/L的NaCl和Na2SO4处理‘石头扁桃’和‘桃扁桃’实生苗植株,处理10 d后分别测定其叶片叶绿素含量、净光合速率、气孔导度、细胞间隙CO2浓度,并观察叶绿体超微结构的变化。研究发现:(1)盐胁迫下,‘石头扁桃’和‘桃扁桃’chl a、chl b均在低浓度盐区含量最高,而在高浓度盐区含量最低,Na2SO4处理区chl a、chl b含量均低于NaCl处理区;(2)‘石头扁桃’和‘桃扁桃’叶片净光合速率随盐浓度的增加而下降,‘石头扁桃’下降的幅度较大;(3)‘桃扁桃’叶片细胞间隙CO2浓度随盐浓度的增加而升高,但‘石头扁桃’叶片细胞间隙的CO2浓度变化没有稳定的规律;(4)2个品种的叶片气孔导度均随盐浓度的增加而降低;(5)盐胁迫后,叶绿体基粒、基质片层扭曲,类囊体肿胀;随盐浓度的增加,形变加剧,叶绿体由椭圆形肿胀成圆形,叶绿体膜解体,且‘石头扁桃’叶绿体对盐胁迫比较敏感。综合分析发现,2种盐胁迫对植物造成伤害的机理不同,‘石头扁桃’的耐盐能力较差。     

壳聚糖对NaCl胁迫下菜用大豆叶绿体蛋白的影响

壳聚糖(CTS)能有效增强植物对盐胁迫的耐受性,但CTS在蛋白质组水平上对菜用大豆幼苗响应盐胁迫的影响尚不清楚.本研究用200 mmol·L-1 CTS和蒸馏水分别喷洒菜用大豆'绿领特早'幼苗叶片,诱导5d后进行NaCl胁迫和无NaCl胁迫营养液处理,在NaCl处理第3天取样提取幼苗叶片叶绿体蛋白,进行同位素标记相对和...     

弱光胁迫对花生功能叶片RuBP羧化酶活性及叶绿体超微结构的影响

间作套种是我国主要的花生(Arachis hypogaea)种植方式之一。然而, 与单作相比, 在间作套种体系中, 花生截获的光能较少, 生长发育差, 产量低, 研究不同品种耐阴机理对选择适宜间作套种的花生品种具有重要意义。该研究用耐阴性不同的两个花生品种‘花育22号’ (强耐阴性)和‘白沙1016’ (弱耐阴性)为材料, 在大田条件下采用不同透光率遮阴网设置50%自然光强(中度弱光胁迫)和15%自然光强(严重弱光胁迫) 2个弱光处理, 从出苗期开始遮阴40天, 以自然光强为对照, 研究了弱光胁迫对花生功能叶片RuBP羧化酶活性和叶绿体超微结构的影响。结果表明: 光强为自然光照50%和15%的处理, ‘花育22号’ RuBP羧化酶活性与对照相比虽有降低, 但差异不显著, 而‘白沙1016’分别比对照低40.1%和59.4%, 显著低于对照。与对照相比, 50%自然光强下‘花育22号’叶绿体数不变, 叶绿体基粒数和基粒片层数显著增多, 叶绿体变长且发育完好, 15%自然光强下, 叶绿体数、基粒数和淀粉粒数显著减少, 叶绿体膜和基粒片层出现破损, 但叶绿体变长, 基粒片层数增加; ‘白沙1016’在50%自然光强下, 叶绿体数目和超微结构变化同‘花育22号’相似, 在15%自然光强下叶绿体变圆, 基粒数的降幅和基粒片层破损程度大于‘花育22号’且基粒片层数减少, 淀粉粒数增多。因此, 弱光胁迫特别是严重弱光胁迫条件下, 功能叶RuBP羧化酶活性降低幅度小、叶绿体超微结构受损程度低是‘花育22号’耐阴的光合生理基础。     

Activities of Antioxidant Enzymes during Senescence of Prunus Armeniaca Leaves

During the period of senescence of apricot leaves changes in photosynthetic pigment contents and in the activities of some antioxidant enzymes (superoxide dismutase, catalase, peroxidase and ascorbate peroxidase) were analysed. Significant changes in pigment contents were, in most cases, correlated with changes in activities of the antioxidant enzymes. Modifications in superoxide dismutase and catalase isoform patterns were also observed during the progression of senescence. Both enzyme activities and isoenzyme patterns proved to be genotype-dependent.     

Effect of Aluminium on Oxidative Stress Related Enzymes Activities in Barley Roots

The impact of aluminium stress on activities of enzymes of the oxidative metabolism: superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), NADH peroxidase (NADH-POD) and oxalate oxidase (OXO) was studied in barley (Hordeum vulgare L. cv. Alfor) root tips. SOD appeared to be involved in detoxification mechanisms at highly toxic Al doses and after long Al exposure. POD and APX, H₂O₂ consuming enzymes, were activated following similar patterns of expression and exhibiting significant correlation between their elevated activities and root growth inhibition. The signalling role of NADH-POD in oxidative stress seems to be more probable than that of OXO, which might be involved in Al toxicity mechanism. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chilling Induced Oxidative Stress in Germinating Wheat Grains as Affected by Water Stress and Calcium

Wheat (Triticum aestivum L.) plants were subjected to mild water stress during grain filling at milk (early, medium, and late) and dough (early, soft, hard) stages. The grains harvested from stressed plants were subjected to low temperature stress of 10 °C for 24 h in presence or absence of 1 mM CaCl₂, and embryos were examined for oxidative injury. The embryos of grains water stressed at milk and soft dough stages showed lowest contents of H₂O₂ and malondialdehyde and highest membrane stability index, ascorbic acid content, and activities of catalase, ascorbate peroxidase, and superoxide dismutase as compared to control embryos or water-stressed at other stages. Presence of Ca²⁺ in the medium reduced H₂O₂ and malondialdehyde content and increased ascorbic acid content, and catalase, ascorbate peroxidase and superoxide dismutase activities.     

铅胁迫对3种藓类植物抗氧化酶活性的影响

采用水培实验研究了重金属Pb对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶(SOD、POD和CAT)活性的影响.结果表明,(1)在1~200 mg·L-1的铅胁迫浓度范围内,Pb对3种藓类植物的SOD活性均具有显著的促进作用,对Pb胁迫的种间敏感性差异为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)POD活性对Pb胁迫的反应趋势有一定差别,尖叶拟船叶藓和匍枝青藓的POD活性随Pb浓度的增加先升后降,湿地匍灯藓的POD活性变化较为平缓,种间敏感性差异为匍枝青藓>尖叶拟船叶藓>湿地匍灯藓;(3)在100 mg·L-1时Pb对湿地匍灯藓CAT活性表现为显著促进作用外,其余在低浓度下显示无显著影响,在高浓度下表现为抑制效应,种间敏感性差异为尖叶拟船叶藓>匍枝青藓>湿地匍灯藓.3种藓类植物的抗氧化酶体系中对Pb胁迫的抵抗起关键作用的是SOD,可作为藓类植物受Pb胁迫的敏感生理指标.3种植物中对Pb胁迫的反应较为敏感的是尖叶拟船叶藓.     

Detoxification of SO2 derivatives in chloroplasts ofHardwickia binata

Intact chloroplasts isolated from sulphur dioxide fumigatedHardwickia binata leaves showed inhibition of PS II electron transport activity without any significant effect on photosystem I. Sulphur dioxide exposed leaves accumulated more hydrogen peroxide than those from non-fumigated plants and this was caused by increase in superoxide radical production. Hydrogen peroxide formation was inhibited by addition of cytochrome C and superoxide disrnutase. In sulphur dioxide fumigated leaves, increase in superoxide dismutase activity showed resistance to sulphite toxicity. The localization of ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase activities in chloroplasts provide evidence for the photogeneration of ascorbate. The scavenging of hydrogen peroxide in chloroplast due to ascorbate regenerated from DHA by the system: PS I → Fd → NADP → glutathione. The system can be considered as a means for preliminary detoxification of sulphur dioxide by chloroplasts     

魔芋葡甘低聚糖对小鼠抗氧化酶活性的影响

研究魔芋葡甘低聚糖对小鼠血浆和肝脏中抗氧化酶活性的影响。魔芋葡甘低聚糖能有效地降低肝脏中丙二醛(MDA)的含量,提高肝脏和血浆中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)的活性。尤以高剂量组效果最好。     

Changes in Activities of Antioxidant Enzymes in Sunflower Leaves of Different Ages

Role of superoxide dismutase isozymes and other antioxidant enzymes was studied in relation to leaf age in sunflower (Helianthus annuus L. cv. ACC 1508) at pre-flowering and grain filling stages. Relative water content (RWC) did not change much in leaves of different age and at the two stages. Protein content declined continuously from the youngest to the oldest leaf, while chlorophyll (Chl) and carotenoids (Car) contents increased down to 7^th/9^th leaf and declined in subsequent older leaves. Protein, Chl and Car contents were higher at pre-flowering than at seed filling stage. Superoxide dismutase (SOD), its isozymes, and ascorbate peroxidase (APO) and catalase (CAT) activities were highest in the 9^th leaf and declined in subsequent older leaves. SOD and APO activities were higher at seed filling, except in oldest senescent (13^th, 15^th) leaves. Among SOD isozymes, Cu/Zn-SOD and Mn-SOD activities accounted for most of the total SOD, and only marginal activity was observed for Fe-SOD. Peroxidase activity increased from youngest to the oldest leaf at pre-flowering stage and down to 13^th leaf at seed filling stage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Seasonal changes in antioxidant level of Scots pine (Pinus sylvestris L.) needles exposed to industrial pollution. II. Enzymatic scavengers activities

The involvement of enzymic antioxidant system, superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase in defense reaction to environmental stress evoked by air and soil pollution, was seasonally studied on three populations of Scots pine (Pinus sylvestris L.) growing on experimental areas close two industrial objects in Poland. The first of them (Luboón) is localised near a phosphate fertiliser factory, the second (Głogów) near a copper foundry, and control stand is placed in Kórnik. Głogów is the most polluted site, where in 1998 monthly mean daily concentrations was: SO₂ - 17 μg·m⁻³, NO_x- 12 μg·m⁻³ and dust containing heavy metals (Cu, Pb, Cd) - 29 μg·m⁻³. Trees in Luboń were influenced for many years by high concentration of SO₂ and fluor compounds. Few years ago emissions were markedly reduced, but changes in the soil (low pH and high concentration of aluminium ions) still influence the growth of trees. In needles of two populations: 3 (Russia) and 8 (Poland), from the polluted sites Głogów and Luboń, activities of superoxide dismutase (SOD) and guaiacol peroxidase (PO) were significantly higher compared to Kórnik. However, in one population (16 - Slovakia), such dependance was not evident. Activity of ascorbate peroxidase (AP) measured in winter was also higher in needles from polluted sites. The results indicated that the sensitivity of free radical scavenging system in Scots pine needles differs among populations.     

Changes in the Activity of Antioxidant Enzymes in Wheat Leaves and Roots as a Function of Nitrogen Source and Supply

The activity of enzymes participating in the systems of antioxidant protection was assayed in the second leaf and roots of 21-day-old wheat seedlings (Triticum aestivum L.) grown in a medium with nitrate (NO^– ₃ treatment), ammonium (NH⁺ ₄ treatment), or without nitrogen added (N-deficiency treatment). The activities of superoxide dismutase (SOD), peroxidase, ascorbate peroxidase, glutathione reductase, and catalase in the leaves and roots of the NH⁺ ₄ plants was significantly higher than in the plants grown in the nitrate medium. The activity of SOD decreased and ascorbate peroxidase markedly increased in leaves, whereas the activity of ascorbate peroxidase increased in the roots of N-deficient plants, as compared to the plants grown in nitrate and ammonium. Low-temperature incubation (5°, 12 h) differentially affected the antioxidant activity of the studied plants. Whereas leaf enzyme activities did not change in the NH⁺ ₄ plants, the activities of SOD, peroxidase, ascorbate peroxidase, and catalase markedly increased in the NO^– ₃ plants. In leaves of the N-deficient plant, the activity of SOD decreased; however, the activity of other enzymes increased. In response to temperature decrease, catalase activity increased in the roots of NO^– ₃ and NH⁺ ₄-plants, whereas in the N-deficient plants, the activity of peroxidase increased. Thus, in wheat, both nitrogen form and nitrogen deficiency changed the time-course of antioxidant enzyme activities in response to low temperature.     

Alleviation of NaCl Stress by Pretreatment with Phytohormones in Vigna radiata

Efficiency of pretreatment as foliar spray of indole-3-acetic acid, gibberellic acid and kinetin, each ranging from 0.1 to 10.0 μM concentration, in restoring the metabolic alterations imposed by NaCl salinity was investigated in Vigna radiata (L.) Wilczek. Glycolate oxidase, superoxide dismutase, catalase and peroxidase activities increased under stress in leaves and roots also. Malondialdehyde content and total peroxide content also increased under stress. All the three hormones used were able to overcome to variable extents the adverse effects of stress imposed by NaCl to these parameters. This revised version was published online in July 2006 with corrections to the Cover Date.