Protective role of proline against salt stress is partially related to the improvement of water status and peroxidase enzyme activity in cucumber

Abstract

A salt-sensitive cucumber cultivar “Jinchun No. 2” (Cucumis sativus L.) was used to investigate the role of proline in alleviating salt stress in cucumber. Proline was applied twice (day 0 and day 4 after salt treatment) as a foliar spray, with a volume of 25?mL per plant at each time. Plant dry weight, leaf relative water content, proline, malondialdehyde (MDA), Na⁺, K⁺ and Cl^? contents, as well as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities in the plants were determined at day 8 after salt treatment. The results showed that 100?mmol?L^–1 NaCl stress significantly decreased plant dry weight, leaf relative water and K⁺ contents, and increased leaf MDA, Na⁺ and Cl^? contents and SOD, POD, CAT and APX activities. However, leaf proline accumulation was not affected by salinity. The exogenous application of proline significantly alleviated the growth inhibition of plants induced by NaCl, and was accompanied by higher leaf relative water content and POD activity, higher proline and Cl^? contents, and lower MDA content and SOD activity. However, there was no significant difference in Na⁺ and K⁺ contents or in CAT and APX activities between proline-treated and untreated plants under salt stress. Taken together, these results suggested that the foliar application of proline was an effective way to improve the salt tolerance of cucumber. The enhanced salt tolerance could be partially attributed to the improved water status and peroxidase enzyme activity in the leaf.     

Physiological responses and adaptive strategies of wheat seedlings to salt and alkali stresses

Effects of salt (NaCl : Na₂SO₄) and alkali (NaHCO₃ : Na₂CO₃) stresses on the contents of inorganic ions and organic solutes in wheat shoots were compared to explore the physiological responses and adaptive strategies of wheat to these stresses. Wheat significantly accumulated Na⁺ and simultaneously accumulated Cl⁻, soluble sugars and proline to maintain osmotic and ionic balance under salt stress. Compared with salt stress, the high pH from alkali stress enhanced Na⁺ accumulation and affected the absorption of inorganic anions. To maintain ionic and osmotic balance, wheat accumulated organic acids, soluble sugars and proline. The accumulation of Cl⁻ and organic acids was the main difference in the physiological responses and adaptive mechanisms to salt and alkali stresses, respectively.     

Effects of saline and alkaline stresses on the germination, growth, photosynthesis, ionic balance and anti-oxidant system in an alkali-tolerant leguminous forage Lathyrus quinquenervius

We compared the effects of saline stress (9:1 molar ratio of NaCl : Na₂SO₄, pH 6.44–6.65) and alkaline stress (9:1 molar ratio of NaHCO₃ : Na₂CO₃, pH 8.71–8.89) on the germination, growth, photosynthesis, ionic balance and activity of anti-oxidant enzymes of Lathyrus quinquenervius to elucidate the physiological adaptive mechanism of plants to alkaline stress (high pH). The results showed that, at a low stress intensity, the effects of saline stress and alkaline stress on L. quinquenervius were similar. Compared with saline stress, high alkaline stress intensity clearly inhibited germination, growth, photosynthesis and root system activity, and led to a sharp increase in Na⁺ and an ion imbalance in the shoots, as well as enhanced H₂O₂ and malondialdehyde content, resulting in severe intracellular oxidative stress. The results indicated that the accumulation of organic acid was a central adaptive mechanism by which L. quinquenervius maintained intracellular ionic balance under alkaline stress. Lathyrus quinquenervius may enhance organic acid synthesis to remedy the shortage of negative charge resulting from the massive influx of Na⁺ and decreased inorganic anions. In addition, saline stress and low alkaline stress slightly enhanced the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), but did not affect catalase (CAT) activity. However, strong alkaline stress significantly enhanced the activities of SOD and APX, and reduced CAT activity. We propose that enhancing the activities of SOD and APX may be a vital mechanism by which L. quinquenervius resists oxidative stress caused by alkaline stress.     

葛根素对小白菜镉损伤的保护作用研究

为探究葛根素(PUE)对小白菜镉(Cd)损伤的保护效果,采取外源添加不同葛根素处理,将小白菜植株随机分为7组,即对照组(CK)、PUE30组(葛根素30μmol·L^-1)、Cd4组(镉4 mg·L^-1)、Cd与PUE共处理组(4+15、4+30、4+45、4+60)。处理30 d后,观察小白菜植株生长状况、测定Cd富集量及抗胁迫生理活性物质,包括叶绿素、抗氧化酶(SOD、APX、CAT、POD)活性及过氧化氢(H₂O₂)、丙二醛(MDA)Vc、可溶性蛋白含量,并用实时荧光定量PCR(qRT-PCR)技术检测抗氧化酶基因(SOD、POD、APX及CAT)表达量。结果表明,与CK组相比,Cd4组小白菜根中Cd含量、H₂O₂和MDA含量显著升高,而地下部鲜重、地上部鲜重、抗氧化酶(SOD、POD和APX)活性和叶绿素含量整体显著降低(P<0.05)。与Cd4组相比,Cd+PUE共处理组小白菜氧化损伤程度减轻,H₂O₂     

La(NO3)3 对盐胁迫下黑麦草幼苗生长及抗逆生理特性的影响

为探讨稀土元素镧(La)对牧草盐胁迫伤害的缓解作用, 采用水培法研究了叶面喷施20 mg·L^-1La(NO₃)₃ 对NaCl 胁迫下黑麦草幼苗生长及其抗逆生理特性的影响。结果表明: 盐胁迫显著抑制黑麦草幼苗的生长, 提高叶片电解质渗漏率及丙二醛(MDA)、O₂^- 和H₂O₂ 含量, 其作用随盐浓度的增大而增强。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白质、脯氨酸含量随盐浓度增大呈先升后降趋势, 可溶性糖和Na⁺/K⁺比逐渐增大, 质膜H⁺-ATP 酶活性逐渐降低, 过氧化物酶(POD)活性及POD 同功酶数量表达增强。喷施La(NO₃)₃ 处理可降低盐胁迫下黑麦草幼苗叶片的O₂^- 和H₂O₂ 含量, 提高SOD、CAT、POD、APX 和质膜H⁺-ATP 酶的活性及POD 同功酶的表达, 使AsA、GSH、可溶性蛋白质、可溶性糖和游离脯氨酸含量及幼苗生物量增加, Na⁺/K⁺比降低。表明La(NO₃)₃ 可通过提高抗氧化系统的活性和积累渗透溶质减轻盐胁迫伤害, 从而提高黑麦草的耐盐性。     

干旱胁迫下H2S对板栗幼苗根系抗氧化特性及呼吸相关酶活性的影响

为探究干旱胁迫下H₂S对板栗幼苗根系特性的影响,以黄棚板栗幼苗为试验材料,通过PEG模拟干旱并进行H₂S供体硫氢化钠(NaHS)和清除剂次牛磺酸(HT)处理,分析板栗幼苗根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)等抗氧化酶活性及丙二醛(MDA)、H₂O₂等抗氧化物质含量,检测苹果酸脱氢酶(MDH)、磷酸果糖激酶(PFK)和葡萄糖-6-磷酸脱氢酶(G-6-PDH)等呼吸代谢相关酶活性。结果表明,0.5 mmol·L^-1 NaHS+15% PEG协同处理24 h后,与15% PEG处理相比,根系SOD、POD、CAT、APX活性分别提高19.64%、24.67%、56.91%、16.29%,根系脯氨酸含量增加15.25%,根系MDA和H₂O₂含量分别降低26.52%和20.86%,MDH、PFK和G-6-PDH活性分别提高27.28%、23.14%和15.36%;而添加H₂S清除剂HT则逆转了上述变化,说明适宜浓度的NaHS能够减轻干旱胁迫对板栗根系膜脂过氧化伤害和对呼吸代谢的抑制,从而有利于提高板栗幼苗对干旱逆境的适应能力。本研究结果为进一步探索H₂S缓解板栗树干旱胁迫的机理提供了理论依据。     

甜菜碱对干旱胁迫下棉花幼苗生理特性的影响

以新疆广泛种植的棉花品种新陆早18号为试材,通过测定棉花幼苗体内脯氨酸、可溶性糖和丙二醛（MDA）的含量及抗氧化酶包括超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）的活性,研究叶面喷施不同浓度甜菜碱（Glycine betaine,GB）对干旱胁迫下棉花幼苗生理特性的影响。结果表明,干旱胁迫下,与对照相比,脯氨酸、可溶性糖、MDA含量及SOD和POD活性都显著提高,喷施甜菜碱后促进脯氨酸和可溶性糖含量进一步提高,酶活也显著升高,同时有效抑制了丙二醛含量的增加,CAT活性受干旱胁迫及甜菜碱的影响较小。研究表明喷施低浓度甜菜碱在一定程度上可以缓解干旱胁迫对棉花幼苗的伤害。     

PEG预处理对盐及镉胁迫下黑麦草生理代谢的影响

为了探讨PEG预处理对盐胁迫和镉胁迫下多年生黑麦草幼苗生理特性的影响,将黑麦草幼苗分别用0,5%,10%,15%,20%,25%(对应水势分别为0,-0.05,-0.15,-0.30,-0.50,-0.77 MPa)的PEG-6000营养液进行预处理后,分别用含150 mmol/L NaCl和Cd~(2+)浓度为10 mg/L的胁迫液培养,然后测定黑麦草幼苗叶片的光合色素含量、MDA含量、游离脯氨酸含量、可溶性糖含量及抗氧化酶(SOD、POD、CAT、APX)活性。结果表明:盐胁迫下15%(-0.30 MPa)PEG预处理和镉胁迫下10%(-0.15 MPa)PEG预处理可以有效提高多年生黑麦草的光合色素含量,降低MDA、游离脯氨酸含量,增加可溶性糖含量,提高抗氧化酶活性。PEG预处理下多年生黑麦草在遭受逆境胁迫时,受到多种生理生化的调节,其生理指标的动态变化是黑麦草应答逆境因子胁迫的重要调节机制,体现了其对逆境胁迫的适应能力以及在多种逆境胁迫下的交叉适应能力。     

铝胁迫下外源抗坏血酸对水稻幼苗抗氧化性能的影响

为探讨外源抗坏血酸(AsA)对铝胁迫下水稻抗氧化损伤的效应,以滇优35号(杂交稻,粳稻)为试验材料,采用溶液培养法研究外源AsA对不同铝浓度(0、50、100、200、400 μmol·L^-1)胁迫下水稻根尖H₂O₂含量及抗氧化酶活性等生理生化指标的影响。结果表明,水稻根尖氧化损伤程度随铝浓度的递增而加剧,与对照相比,400 μmol·L^-1铝胁迫可导致水稻根尖H₂O₂和MDA含量增加1.53和3.16倍,脯氨酸含量、SOD、POD、APX和CAT活性分别增加1.73、1.39、1.42、1.76和1.56倍,内源AsA含量减少0.53倍;而施用外源AsA处理的根尖H₂O₂和MDA含量只增加1.04和2.69倍,内源AsA含量减少0.46倍,脯氨酸含量增加1.96倍,SOD、POD、APX和CAT活性分别增加1.48、1.63、1.90和1.89倍。综上所述,外源AsA可通过增强渗透调节物质含量来维护质膜结构的完整性,增强抗氧化酶活性和内源AsA含量,降低根尖H₂O₂的积累和质膜过氧化程度,促进水稻在铝胁迫条件下的生长。本研究结果为进一步探索外源AsA缓解水稻铝毒的机理提供了一定的理论依据。     

氮锌配施对不同玉米品种灌浆期生理特性和籽粒氮锌含量的影响

提高粮食作物中可食部分的锌生物有效性是解决人体缺锌的重要措施。为研究氮锌肥料施用对玉米籽粒锌营养的影响,本研究以郑单958和谷神玉66为试验材料,在大田条件下研究3个氮水平(90、180 和225 kg N·hm^-2)和2个喷锌处理(0和4.5 kg·hm^-2 ZnSO₄·7H₂O)下玉米籽粒产量和氮锌含量以及灌浆期叶片生理特性的变化。结果表明,吐丝后,与施氮量90 kg·hm^-2处理相比,施氮量180和225 kg·hm^-2处理提高了吐丝后穗位叶SPAD值及硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、碳酸酐酶(CA)、超氧化物歧化酶(SOD)活性和灌浆后期PSⅡ综合性能指数(PI),降低了丙二醛(MDA)含量。施锌能提高吐丝后穗位叶CA、SOD、过氧化物酶(POD)、过氧化氢酶(CAT)活性和灌浆后期SPAD值和PI,降低MDA含量。2个品种相比,谷神玉66灌浆后期穗位叶SPAD值、叶片初始荧光(F_o)和最大荧光(F_m)较高,而灌浆前期穗位叶PI和吐丝后NR、CA、SOD以及POD活性则以郑单958较高。施氮量为90 kg·hm^-2时,玉米籽粒产量平均为8.55 t·hm^-2,随着施氮量增加,玉米籽粒产量显著提高。籽粒中氮含量以施氮量180 kg·hm^-2时最高,为14.85 g·kg^-1。施氮量90和180 kg·hm^-2时,籽粒锌含量平均为27.2 mg·kg^-1,显著高于施氮量225 kg·hm^-2处理。与不施锌相比,喷锌后玉米籽粒产量未有显著变化,籽粒中氮、锌含量分别增加了11.7%和18.0%。郑单958籽粒产量较谷神玉66提高了3.8%,籽粒氮锌含量则分别减少了11.9%和5.3%。综合来看,施氮量为180 kg N·hm^-2时,与喷施ZnSO₄·7H₂O 4.5 kg·hm^-2 配合施用能够增强玉米灌浆期叶片SPAD和荧光特性,提高氮锌代谢关键酶活性,增强氧自由基清除系统酶活性,减弱膜脂过氧化作用的伤害,促进籽粒中氮、锌的吸收和累积。本研究结果可为玉米生产中优化锌生物强化措施提供理论依据。     

不同光强下龙葵对镉的吸收积累及生理响应

采用土培方法探讨了不同光强（自然光和50%遮光）和镉（Cd）不同添加量（0、 25、 50、 75和100 mg/kg）复合处理下,龙葵对Cd的吸收累积特征,超氧化物歧化酶（SOD）、 过氧化物酶（POD）、 过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性以及叶绿素、 丙二醛（MDA）、 谷胱甘肽（GSH）和植物螯合肽（PCs）含量等的变化特征。结果表明, 自然光条件下龙葵叶绿素b、 叶绿素a+b以及地上和地下部Cd富集量均显著低于遮光处理; 叶和根的SOD、 POD、 CAT和APX活性在自然光条件下随土壤Cd添加量的增大先升后降,而在遮光处理下则持续升高; 除Cd 25 mg/kg处理时根POD及叶CAT活性在不同光强处理下没有显著差异外,其余Cd添加量处理下SOD、 POD、 CAT和APX活性在自然光条件下均显著高于遮光处理; 自然光条件下龙葵叶和根的MDA含量显著高于遮光处理,而叶和根的GSH含量和叶中PCs含量均显著低于遮光处理。研究结果表明,遮光环境促进了龙葵对Cd的富集,并且减轻了Cd对龙葵的氧化胁迫。     

Long-term application of animal slurries to grassland alters soil cation balance

Abstract. Soil samples from a 32-year grassland field experiment were taken from 0–5, 5–10, and 10–15 cm soil depths in February 2002. Plots received annual treatments of unamended control, mineral fertilizer, three rates of pig slurry and three rates of cow slurry, each with six replicates. Samples were analysed for cation exchange capacity (CEC), exchangeable cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), pH and Olsen P. Exchangeable sodium percentage (ESP) was calculated as a sodicity indicator. Mean ESP was generally greater for slurry treatments than the control, with a trend of increasing ESP with application rate. This was particularly marked for cow slurry. At 0–5 cm depth ESP increased from 1.18 in the control to 1.75 at the highest rate of pig slurry and 5.60 at the highest rate of cow slurry. Similar trends were shown for CEC, exchangeable Na⁺, K⁺ and Mg²⁺, Ca²⁺ and Olsen P. The build-up of soil P due to slurry applications, together with this combination of physical and chemical factors, may increase the risk of P loss to surface waters, particularly from soils receiving high rates of cow slurry.     

外源NO对盐胁迫下甜高粱种子萌发和幼苗生长的影响

为探究外源NO对盐胁迫下甜高粱种子萌发和幼苗生长的影响,以国能4号甜高粱为试验材料,采用不同浓度(0.05、0.1和0.2 mmol·L^-1)硝普钠(SNP,NO供体)处理1.6%NaCl胁迫下的种子和幼苗,统计种子发芽数,测定幼苗叶片叶绿素、脯氨酸、可溶性糖、可溶性蛋白、丙二醛(MDA)含量及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性等生理生化指标。结果表明,盐胁迫抑制了甜高粱种子的萌发,种子发芽指标(种子发芽率、发芽势和发芽指数)显著降低,1.6%NaCl是甜高粱种子萌发的敏感盐浓度;喷施不同浓度SNP可显著提高盐胁迫下甜高粱种子的发芽率及幼苗叶片叶绿素、可溶性糖、可溶性蛋白和脯氨酸含量,降低叶片MDA含量,增强抗氧化酶活性,其中0.1 mmol·L^-1SNP处理效果最佳。0.1 mmol·L^-1SNP处理下,与单独盐浓度处理相比,甜高粱种子发芽率、发芽势和发芽指数分别增加了29.51%、39.21%和38.91%;幼苗叶片叶绿素a、叶绿素b、总叶绿素、可溶性糖、可溶性蛋白和脯氨酸含量分别提高了230.00%、184.38%、214.13%、17.00%、8.78%和40.63%;MDA含量降低了34.01%;SOD、POD、CAT和APX活性分别增强了33.38%、55.75%、23.17%和116.46%。综上,盐胁迫下适宜浓度的SNP处理,可提高甜高粱幼苗叶片渗透调节物质含量,增强抗氧化酶活性,清除体内活性氧,从而促进幼苗生长,增强植株抗盐性。本研究结果为提高甜高粱耐盐性及揭示其耐盐机制提供了理论依据。     

外源一氧化氮对NaCl胁迫下番茄幼苗活性氧代谢的影响

研究了在100 mmol/L NaCl胁迫下,外源NO供体硝普钠（SNP）处理对耐盐性不同的2个番茄品种（沪番‘1480’和沪番‘2496’）幼苗叶片活性氧（ROS）水平和保护酶活性的影响。结果表明,外源NO提高了盐胁迫下SOD、POD、CAT和APX活性,AsA和GSH含量以及脯氨酸和可溶性糖含量,降低了MDA含量和O2- 产生速率;与耐盐品种‘1480’相比,NO处理对盐敏感品种‘2496’效果更明显。表明外源NO通过促进盐胁迫下保护酶活性、抗氧化剂和渗透调节物质的提高,降低ROS水平,缓解NaCl胁迫对番茄幼苗生长的抑制作用,增强植株的耐盐能力。     

几种杀虫剂胁迫对黄瓜幼苗抗氧化酶活性和相关生理指标的影响

明确杀虫剂多次施用后对黄瓜幼苗抗氧化酶活性和相关生理指标的影响,对指导黄瓜(Cucumis sativus L.)合理用药具有重要作用。本研究以室内盆栽的黄瓜幼苗为试材,研究了几种常用化学杀虫剂吡虫啉、啶虫脒、溴氰菊酯及生物杀虫剂玫烟色棒束孢对黄瓜幼苗抗氧化酶活性(SOD、POD、CAT)及丙二醛MDA、脯氨酸和蛋白质含量的影响。结果表明:不同杀虫剂对黄瓜幼苗抗氧化酶活性及相关生理指标的影响不同。当供试3种化学杀虫剂胁迫黄瓜幼苗2 d时,其体内SOD、POD、CAT活性与对照无显著差异;当胁迫时间延长到4 d时,溴氰菊酯和啶虫脒处理的黄瓜幼苗体内3种抗氧化酶活均明显升高且与对照差异显著;当胁迫时间延长到6 d时,3种化学杀虫剂均造成黄瓜幼苗体内SOD、POD活性升高且与对照差异显著,其中溴氰菊酯影响较吡虫啉和啶虫咪严重;胁迫8~10 d后,各处理黄瓜幼苗体内3种抗氧化酶活性均开始下降或恢复正常。同时,3种化学杀虫剂胁迫黄瓜幼苗4~8 d时,MDA和脯氨酸含量升高并与对照差异显著;胁迫10 d时,啶虫咪和溴氰菊酯胁迫的黄瓜幼苗MDA含量仍显著高于对照,而脯氨酸含量开始下降并趋于正常。此外,3种化学杀虫剂胁迫黄瓜幼苗2~8 d时均造成其蛋白质含量的降低,而生物杀虫剂玫烟色棒束孢胁迫对黄瓜幼苗SOD、POD、CAT活性及MDA、脯氨酸和蛋白质含量均没有显著影响。可见生物杀虫剂玫烟色棒束孢较3种化学杀虫剂对黄瓜幼苗安全,黄瓜幼苗受化学杀虫剂胁迫后需要一个过程才能修复杀虫剂对其自身造成的伤害。     

Physiological and growth responses of two different salt-sensitive cucumber cultivars to NaCl stress

Abstract

The effect of NaCl stress on the growth, membrane permeability, anti-oxidant enzyme activities and ion content of cucumber seedlings was investigated. Two cultivars (Jinchun No. 2, a relatively salt-sensitive cultivar, and Zaoduojia, a relatively salt-tolerant cultivar) of cucumber were used. Shoot and root dry weights, plant height, stem diameter, leaf area and leaf number of both cultivars decreased when NaCl concentrations increased. The decreases in shoot and root dry weights and leaf area were more significant in Jinchun No. 2 than in Zaoduojia. Meanwhile, the salt injury index, the membrane permeability, malondialdehyde (MDA) contents, superoxide dismutase (SOD) and peroxidase (POD) activities of both cultivars increased significantly with salt stress, and the increases in the salt injury index and MDA were higher in Jinchun No. 2 than in Zaoduojia, whereas the increase in POD activity was lower in Jinchun No. 2 than in Zaoduojia. Free proline content of Zaoduojia increased markedly with increasing concentrations of NaCl, whereas the content of Jinchun No. 2 was unaffected by salt stress. In addition, the contents of Na⁺ in the leaf, stem and root of both cultivars increased significantly, whereas the contents of K⁺ decreased significantly, resulting in an increase in the Na⁺/K⁺ ratio when NaCl concentrations increased. These results suggest that Zaoduojia exhibits a better protection mechanism against oxidative damage and lipid peroxidation by maintaining higher proline content and POD activity than the salt-sensitive Jinchun No. 2 cultivar.     

Interaction forces between soil particles: shear moduli of the < 2 μm size fraction

The shear moduli of the < 2 μm size fraction of three soils have been measured for samples of 10–35% w/w solid. Samples were thixotropic, the shear modulus increasing with time. This increase can be described by simple models and visualized in terms of the formation of links between particles. For a given soil the shear modulus increases with ionic form in the order Ca²⁺∼Mg²⁺ + + < Li⁺ and varies in a complex manner with electrolyte concentration.     

荆芥幼苗对盐胁迫的生理响应

为探究盐胁迫对荆芥幼苗生理特性的影响,采用盆栽砂培试验,研究不同浓度盐胁迫(0、25、50、75和100 mmol·L^-1 NaCl)下荆芥幼苗生长、质膜稳定性、渗透调节、抗氧化酶系统、离子吸收和分配的变化。结果表明,随着盐浓度的增加,荆芥盐害指数逐渐升高,幼苗株高增加速率和比叶面积均逐渐降低,单株干重和叶绿素含量均呈先增加后减少的趋势,且均在25 mmol·L^-1 NaCl处理下达到最大;叶片中丙二醛(MDA)含量和电解质渗漏率均显著增加;可溶性蛋白和脯氨酸含量均呈先增加后减少趋势,且分别在50和75 mmol·L^-1 NaCl处理下达到最大,而可溶性糖含量则不断上升;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性均呈先上升后下降的趋势,在25 mmol·L^-1 NaCl处理下达到最大,而过氧化物酶(POD)活性则持续下降。盐胁迫下,荆芥的根、茎、叶大量积累Na^+,但主要集中在地上部分,同时各部位K^+、Ca²⁺含量及K^+/Na^+、Ca²⁺/Na^+值均显著下降。综上,荆芥幼苗对盐胁迫极为敏感,但对低浓度的盐胁迫(25 mmol·L^-1 NaCl)具有一定的耐受性。本研究结果为荆芥的规范化栽培和抗逆驯化研究奠定了理论基础。     

干旱处理下不同烤烟品系的生理差异研究

为培育抗性优良的烤烟品种,探究烤烟的耐旱特性及机理,以烤烟品系LY1306、中烟100和红花大金元为试验材料,研究在聚乙二醇6000(PEG-6000)模拟干旱胁迫和水分控制的干旱处理下,各烤烟品系叶片抗氧化酶类活性,丙二醛(MDA)和脯氨酸含量变化,以及光合生理特性和叶片细胞超微结构的差异。结果表明,25%PEG-6000胁迫下,LY1306能保持较好的生理状态,具有较高的SOD活性和较强的脯氨酸渗透调节能力;中烟100的个别叶片出现萎蔫,SOD活性较LY1306低,较对照组POD和CAT活性显著降低,MDA含量较高;红花大金元叶片出现严重萎蔫,CAT活性降低幅度最大,脯氨酸积累量较高。在反复缺水干旱条件下,LY1306能够维持较高的CAT活性,MDA积累量少,水分利用率较高,蒸腾速率较低,细胞中叶绿体数量和叶绿体形态维持正常。红花大金元的POD活性增长明显,脯氨酸含量显著增长,但MDA积累量较大,叶绿体变形且数量明显减少。中烟100的POD活性较高,脯氨酸积累量较大,叶绿体结构较完整。综上,LY1306在干旱胁迫下具有较强的清除活性氧和脯氨酸渗透调节能力,综合抗旱能力较好。本研究结果为培育抗旱烤烟品种提供了理论依据。     

过量表达盐芥TsIPK2基因增强转基因水稻耐盐性

【目的】本试验以野生型(WT)和转盐芥TsIPK2基因的水稻为材料,研究NaCl胁迫条件下过量表达TsIPK2基因对水稻植株抗盐胁迫能力的影响。【方法】取水稻材料种子和其3叶龄幼苗,分别在不同NaCl浓度(0、50、100、150、200 mmol/L)下进行处理。检测WT与过量表达TsIPK2基因水稻种子的发芽率、主根长和芽长、幼苗的丙二醛(MDA)和脯氨酸的含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,以及与胁迫相关的5个基因的表达。【结果】在盐胁迫下,与野生型相比,转基因水稻具有更好的发芽率、主根长和芽长。野生型和转基因水稻两者的脯氨酸含量增加,转基因水稻的积累量显著高于野生型,但是转基因水稻MDA含量增加幅度小于野生型。野生型和转基因水稻幼苗SOD酶活性均增加,但转基因植株的酶活性显著高于野生型;二者POD酶活性呈现先升高后下降的趋势,但是二者活性没有显著的差别;转基因水稻的CAT活性也呈现先升高后下降的趋势,然而野生型水稻的CAT活性在盐胁迫下没有显著的变化。高盐处理后,野生型和转基因水稻的5个与胁迫相关的基因表达倍数都增加,与野生型相比,转基因水稻的OsP5CS1、OsSOD、OsCATB和OsLEA3的表达量显著升高,而OsPOX1基因的表达量变化不显著。【结论】过量表达TsIPK2基因能够通过增强水稻的渗透调节能力、抗氧化胁迫能力并调节胁迫相关基因的表达,以提高水稻的耐盐性。