CO_2激光预处理对PEG6000胁迫下小麦幼苗根中抗氧化酶活性的影响

用CO2激光对小麦种子分别辐照0、1、3、5min,待其生长至12d时,用10%(W/V)PEG6000胁迫其幼苗,研究激光预处理对PEG6000水分胁迫下小麦幼苗根部脂质过氧化伤害的防护作用。结果表明,CO2激光预处理3min可使水分胁迫的小麦幼苗根部MDA、H2O2含量和O2.-产生速率显著降低(P0.05),可显著提高(P0.05)小麦幼苗根部SOD、POD、CAT、APX活性和根长、根干重。激光预处理3min可抑制由水分胁迫引起的小麦幼苗根部脂质过氧化作用。     

INFLUENCE OF He-Ne LASER IRRADIATION ON PROTECTIVE ENZYME ACTIVITIES AND LIPID PEROXIDATION IN WHEAT SEEDLINGS BY DROUGHT STRESS DAMAGE

 用He-Ne激光(5.23 mW·mm^–2)处理经5%、10%、15% PEG6000胁迫的小麦幼苗, 分析了干旱胁迫条件下激光处理对小麦幼苗保护酶活性及脂质过氧化作用的影响。适度干旱胁迫的小麦幼苗经He-Ne激光辐照后, 丙二醛(MDA)含量和超氧自由基(O₂^–.)产生速率显著降低(p<0.05), 而过氧化物酶(POD)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)含量却显著增加(p<0.05)。总体上看, 5%和10% PEG6000胁迫的小麦幼苗经激光辐照3 min后抗旱性增强。     

水杨酸对锌胁迫下小麦幼苗生长抑制的缓解效应

以小麦品种‘新麦18’为材料,采用室内水培实验研究了不同浓度水杨酸(SA)处理对300 mg.L-1锌胁迫下小麦种子萌发和幼苗生长的影响。结果表明:在Zn2+胁迫下,小麦种子的发芽势和发芽率、幼苗根长、芽长以及幼苗叶片的可溶性蛋白含量、根系活力显著降低,而脯氨酸和丙二醛(MDA)含量显著增加(P<0.05);外施SA显著提高了Zn2+胁迫下小麦种子的发芽势和发芽率,同时也使Zn2+胁迫7 d后的小麦幼苗的根长、芽长,幼苗叶片的脯氨酸和可溶性蛋白含量以及根系活力显著升高,膜脂过氧化产物MDA含量却显著降低(P<0.05)。由此可见,外施SA可通过提高小麦幼苗根长和芽长来增加幼苗根系活力,通过提高小麦幼苗可溶性蛋白含量、脯氨酸含量来维持细胞膜的稳定性,降低膜脂过氧化伤害程度,从而缓解了Zn2+胁迫对幼苗生长的抑制,并以14 mg.L-1外源水杨酸缓解效果最好。     

CO2激光预处理对PEG6000胁迫下小麦幼苗根中抗氧化酶活性的影响

用CO2激光对小麦种子分别辐照0、1、3、5min,待其生长至12d时,用10%（W/V）PEG6000胁迫其幼苗,研究激光预处理对PEG6000水分胁迫下小麦幼苗根部脂质过氧化伤害的防护作用。结果表明,CO2激光预处理3min可使水分胁迫的小麦幼苗根部MDA、H2O2含量和O2.-产生速率显著降低（P〈0.05）,可显著提高（P〈0.05）小麦幼苗根部SOD、POD、CAT、APX活性和根长、根干重。激光预处理3min可抑制由水分胁迫引起的小麦幼苗根部脂质过氧化作用。     

He-Ne激光和增强UV-B辐射对小麦幼苗蛋白质代谢的影响

采用He-Ne激光(5 mW.mm-2)和增强UV-B(10.08 kJ.m-2.d-1)辐照‘晋麦8号’小麦幼苗,5 d后测定各处理组小麦叶片的蛋白酶、转氨酶活性以及可溶性蛋白质含量与组成的变化。结果显示,增强UV-B辐射使小麦叶片蛋白酶活性极显著升高,转氨酶活性降低,可溶性蛋白质含量极显著下降,蛋白质谱带增加;单独He-Ne激光处理使蛋白酶活性下降,转氨酶活性升高,可溶性蛋白质含量增加,对蛋白质条带影响不明显;与单独UV-B辐射相比,经He-Ne激光辐照和UV-B辐射复合处理后,蛋白酶的活性明显降低,转氨酶的活性增加,可溶性蛋白质含量增加,并且使UV-B辐射诱导出的新带减弱或消失。研究发现,增强UV-B辐射能减弱小麦幼苗蛋白代谢中正常基因的表达,但又激活了一些抗性基因的表达而诱导产生新的胁迫蛋白;一定剂量的He-Ne激光辐照可解除UV-B对小麦幼苗正常基因表达的抑制而使其蛋白质代谢加强。     

He-Ne激光预处理对镉胁迫下小麦幼苗生理特性的影响

用He-Ne激光（波长632.8 nm,辐射剂量5.43 mW/mm²）对萌动小麦种子辐照5 min,待幼苗长至一叶一心时,用150 μmol/L CdCl₂溶液进行胁迫处理,研究He-Ne激光预处理对镉（Cd²⁺）胁迫下小麦幼苗生长发育和生理特性的影响。结果显示:He-Ne激光预处理能显著降低Cd²⁺胁迫下小麦幼苗中丙二醛（MDA）、过氧化氢（H₂O₂）含量及超氧自由基（O^-·₂）产生速率,显著提高幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸氧化酶（APX）活性,并使叶片抗氧化物质谷胱甘肽(GSH)和抗坏血酸(AsA)含量以及幼苗株高、根长和干重增加。研究表明,He-Ne激光预处理可有效缓解镉胁迫对小麦幼苗生长的抑制作用,并通过促进其幼苗中酶类和非酶类抗氧化剂的产生,有效减少镉胁迫产生的脂质过氧化物含量,从而提高其耐镉性。     

He-Ne激光对增强UV-B辐射小麦幼苗多胺氧化酶和过氧化物酶活性的研究

采用He-Ne激光辐照对增强UV-B辐射后小麦幼苗的损伤修复作用进行了研究。小麦种子在盛有湿滤纸的培养皿内25℃下进行萌发。萌发后小麦幼苗在经10.08 kJ·m^-2·d^-1的增强UV-B辐射,然后再用5 mW·mm^-2的He-Ne激光进行辐照。通过小麦幼苗叶片游离脯氨酸含量、多胺氧化酶和过氧化物酶的活性变化,测定了He-Ne激光对小麦UV-B损伤的修复情况。结果表明,游离脯氨酸、多胺氧化酶、过氧化物酶的变化同小麦幼苗损伤的修复的能力相关联。He-Ne激光辐照可使由增强UV-B辐射后诱导叶片升高的游离脯氨酸含量降低。增强UV-B辐射对多胺氧化酶（PAO）活性和过氧化物酶（POD）活性呈促进的作用。辐射6 d后PAO和POD总的活性呈正相关性,PAO和POD活性都呈现B组最高,L组最低,且差异显著。显示He-Ne激光对两种酶由于增强UV-B辐照造成的伤害有一定的修复。     

外源GSH对盐胁迫下番茄幼苗生长及抗逆生理指标的影响

采用营养液栽培法,研究外源谷胱甘肽(GSH)对NaCl胁迫下番茄幼苗生长、根系活力、电解质渗透率和丙二醛(MDA)、脯氨酸(Pro)、可溶性糖含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响,为利用外源物质减轻盐胁迫伤害提供理论依据。结果显示:(1)NaCl胁迫显著抑制了番茄幼苗的生长、根系活力和SOD、POD、CAT活性,提高了电解质渗透率及MDA、Pro、可溶性糖含量;(2)外源喷施GSH能够诱导NaCl胁迫下番茄幼苗叶片抗氧化酶SOD、POD、CAT活性上调,电解质渗透率及MDA含量下降,Pro和可溶性糖含量恢复至对照水平;(3)外源喷施还原型谷胱甘肽抑制剂(BSO)使NaCl胁迫下番茄幼苗的根系活力以及抗氧化酶SOD、POD、CAT活性下降,脯氨酸含量提高;(4)喷施GSH可诱导BSO和NaCl共处理番茄植株的根系活力、SOD、POD、CAT活性提高,MDA和Pro含量降低。研究表明,外源GSH可通过提高促进盐胁迫下番茄幼苗植株渗透调节能力及清除活性氧的酶促系统的防御能力、降低细胞膜脂过氧化程度、保护膜结构的完整性,从而有效缓解NaCl胁迫对番茄幼苗生长的抑制,提高其耐盐性。     

He-Ne激光对增强UV-B辐射下小麦幼苗膜脂过氧化的缓解作用

采用He-Ne激光(5 mW/mm2)辐照增强UV-B辐射(10.08 kJ/m2.d)的晋麦8号小麦幼苗,通过测定小麦幼苗叶片细胞质膜透性、丙二醛(MDA)的含量以及脂氧合酶(LOX)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和谷光苷肽过氧化物酶(GPX)的活性变化,研究He-Ne激光对增强UV-B辐射的小麦幼苗膜脂过氧化的影响。结果显示,He-Ne激光辐照可使经UV-B辐射后小麦幼苗叶片质膜相对透性、MDA含量、LOX活性降低,而使CAT、APX和GPX的活性均升高。分析表明UV-B辐射增强可导致膜脂过氧化加剧,而一定剂量的He-Ne激光能够通过促进酶促抗氧化系统酶的活性来缓解紫外线辐射下小麦幼苗的膜脂过氧化作用。     

CO2激光处理对干旱胁迫小麦幼苗谷胱甘肽抗氧化酶系统的影响

用CO2激光(波长10600 nm,辐射剂量20.1 mW/mm2)对萌动小麦种子分别辐照0、 1、 3、 5 min, 待其长至12 d时,用10%(W/V)PEG 6000胁迫其幼苗.结果表明:CO2激光处理1、 3、 5 min显著提高了还原型谷胱甘肽(GSH)含量,显著降低了氧化型谷胱甘肽(GSSG)含量(5 min除外),导致GSH/GSSG比率显著上升.3 min激光处理显著提高了干旱胁迫下小麦幼苗叶片谷胱甘肽还原酶(GR)和谷胱甘肽-S-转移酶(GST)活性.通过参与降解因干旱胁迫而过量产生的过氧化产物,实现了细胞解毒功能.此外,1 min和3 min激光处理可显著提高干旱胁迫下小麦幼苗抗坏血酸氧化酶(APX)活性和抗坏血酸(AsA)含量,提高了组织内部的抗氧化能力,从而起到保护作用.     

接种两种固氮菌增强小麦幼苗抗渗透胁迫及生长能力

苗期是小麦(Triticum aestivum)物质和能量积累的关键时期, 苗期干旱影响小麦的后期群体建成。利用田菁茎瘤固氮根瘤菌(Azorhizobium caulinodans) ‘ORS571’与巴西固氮螺菌(Azospirillum brasilense) ‘Yu62’浸种侵染小麦和聚乙二醇(PEG)模拟渗透胁迫, 研究渗透胁迫下接菌小麦种子的发芽状况; 利用固氮菌涂抹小麦幼苗叶部, 测定PEG模拟渗透胁迫下小麦幼苗根体积、叶片相对含水量、脯氨酸含量及可溶性蛋白含量, 探究固氮菌增强小麦幼苗抗渗透胁迫的能力。结果表明, 接种混合固氮菌后在渗透胁迫下小麦种子的发芽率明显提高; 在渗透胁迫下叶部涂抹固氮菌小麦的根体积、叶片相对含水量、脯氨酸含量及可溶性蛋白含量明显升高, 表明接种固氮菌可提高小麦幼苗的抗渗透胁迫能力, 且混合固氮菌对小麦幼苗叶片的增强效果优于单一固氮菌。     

模拟干旱胁迫对枣树幼苗的抗氧化系统和渗透调节的影响

用不同浓度的PEG-6000对抗旱性不同的1年生枣树(Zizyphus jujuba)幼苗进行渗透胁迫处理后,研究了不同抗旱性品种枣树幼苗的抗氧化酶活性和渗透调节物质含量的变化.结果显示,干旱胁迫下3种枣苗叶片的相对含水量(RWC)均降低,丙二醛(MDA)含量和细胞质膜相对透性均增加.在30%PEG胁迫下除骏枣1号的SOD活性降低外,3个品种枣苗在干旱胁迫下SOD和POD活性都增加;狗头枣2号的过氧化氢酶(CAT)活性在胁迫下明显增加,而木枣1号和骏枣1号的CAT活性均随着胁迫程度的增加而逐渐下降;木枣1号和骏枣1号的APX活性随着胁迫程度的增加先增加后降低,而狗头枣2号明显增加.干旱胁迫下,除骏枣1号的脯氨酸(Pro)含量和木枣1号的可溶性糖含量在30%的胁迫水平下降低(P>0.05)外,3种干旱胁迫水平下3个品种枣苗的Pro和可溶性糖含量均增加.总之,干旱胁迫下,枣苗叶片相对含水量、抗氧化酶(SOD、POD、CAT和APX)活性、渗透调节物质Pro和可溶性糖含量均为:狗头枣2号>木枣1号>骏枣1号,而MDA含量和膜透性均为骏枣1号>木枣1号>狗头枣2号,表明3个品种的抗旱性为:狗头枣2号>木枣1号>骏枣1号,研究结果与其品种的实际抗旱性一致.     

转基因烟草在PEG6000模拟干旱胁迫条件下的生理响应

该研究以转高山离子芥的CbPLDα、CbPLDβ基因烟草为材料,研究了渗透调节物质和保护酶系对PEG6000溶液模拟干旱胁迫的响应机制.结果表明:渗透调节物质脯氨酸、可溶性糖、可溶性蛋白分别以各自不同的响应方式在干旱胁迫下增强转基因烟草的抗旱性,且在所有浓度PEG6000模拟的干旱胁迫下,转基因烟草的脯氨酸、可溶性糖、可溶性蛋白的含量始终显著高于野生型烟草(P<0.05).说明干旱胁迫下两种转基因烟草的渗透调节能力要强于野生型烟草.保护酶系中,超氧化物歧化酶(SOD)和过氧化物酶(POD)在减轻干旱胁迫下转基因烟草膜脂过氧化伤害中起到协同互补作用,而过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)在干旱胁迫下转基因烟草清除过氧化氢机制中发挥主要作用,说明保护酶系在抵制干旱胁迫和保护转基因烟草免受干旱伤害方面具有重要的生物学功能,这从生理角度揭示了高山离子芥CbPLDα、CbPLDβ响应干旱的生理生态机理.综上,高山离子芥CbPLDα、CbPLDβ基因参与了干旱胁迫下烟草的膜稳定性调节、渗透调节物质的积累和抗氧化酶系的调控.该研究结果为提高植物抗旱性研究及应用提供了新的基因资源,对于加强PLD功能研究、补充植物抗干旱理论及抗低温干旱育种种质资源的开发利用具有重要意义.     

Impact of osmotic stress on physiological and biochemical characteristics in drought-susceptible and drought-resistant wheat genotypes

In this study, the seedlings of two wheat cultivars were used: drought-resistant Chinese Spring (CS) and drought-susceptible (SQ1). Seedlings were subjected to osmotic stress in order to assess the differences in response to drought stress between resistant and susceptible genotype. The aim of the experiment was to evaluate the changes in physiological and biochemical characteristics and to establish the optimum osmotic stress level in which differences in drought resistance between the genotypes could be revealed. Plants were subjected to osmotic stress by supplementing the root medium with three concentrations of PEG 6000. Seedlings were grown for 21 days in control conditions and then the plants were subjected to osmotic stress for 7 days by supplementing the root medium with three concentrations of PEG 6000 (D1, D2, D3) applied in two steps: during the first 3 days of treatment ?0.50, ?0.75 and ?1.00 and next ?0.75, ?1.25 and ?1.5 MPa, respectively. Measurements of gas exchange parameters, chlorophyll content, height of seedlings, length of root, leaf and root water content, leaf osmotic potential, lipid peroxidation, and contents of soluble carbohydrates and proline were taken. The results highlighted statistically significant differences in most traits for treatment D2 and emphasized that these conditions were optimum for expressing differences in the responses to osmotic stress between SQ1 and CS wheat genotypes. The level of osmotic stress defined in this study as most suitable for differentiating drought resistance of wheat genotypes will be used in further research for genetic characterization of this trait in wheat through QTL analysis of mapping population of doubled haploid lines derived from CS and SQ1.     

The investigation on accumulation levels of proline and stress parameters of the maize (<Emphasis Type="Italic">Zea</Emphasis> <Emphasis Type="Italic">mays</Emphasis> L.) plants under salt and water stress

The present study was carried out to determine interactive and comparative effects of salinity and water stress on growth, proline accumulation, chlorophyll, carotenoid and macro nutrient content and antioxidative enzymes such as superoxide dismutase (SOD), guaiacol peroxidase (POX), and polyphenol oxidase (PPO) in hydroponically grown maize (Zea mays L.cv DKC647) plants. Plants were treated two salt (NaCl) concentrations and polyethylene glycol 6000 (PEG 6000) to create water stress. The results obtained from this experiment show that high salinity reduced growth through decreasing shoot and root dry and fresh weight, chlorophyll, and carotenoid content, but PEG treatment had no significant effect on this parameters. Under NaCl and PEG 6000 treatment, uptake and translocation of mineral nutrients changed drastically. The high presence of Na⁺ in nutrient solution affected considerably the plant nutritional requirement, especially influencing the uptake of Ca²⁺ and K⁺, which were restricted for competition. Proline accumulation, and SOD, POX and PPO activities were increased with the increasing intensity of NaCl stress, but PEG 6000 treatment in addition to NaCl had more significant effect on this enzyme activities. These results suggest that maize plants may be increased proline content to maintain osmotic adjustment and increased the activity of antioxidant enzymes to have a better protection against active oxygen species (AOS) under salt and water stress.     

Relationships between polyamines, ethylene, osmoprotectants and antioxidant enzymes activities in wheat seedlings after short-term PEG- and NaCl-induced stresses

Contents of ethylene, osmoprotectants, levels and forms of polyamines (PAs) and activities of antioxidant enzymes in the leaves and roots were investigated for five wheat cultivar seedlings (differing in drought tolerance) exposed to osmotic stress (?1.5 MPa). Stress was induced by 2-day-long treatment of plants with polyethylene glycol 6000 (PEG) or NaCl added to hydroponic cultures. Nawra, Parabola and Manu cv. (drought tolerant) showed a marked increase in osmoprotectors (proline and soluble carbohydrates, mainly glucose, saccharose and maltose), free PAs (putrescine Put, spermidine Spd and spermine Spm) and Spd-conjugated levels, in both leaves and roots, after PEG-treatments. Radunia and Raweta (drought sensitive) exhibited smaller changes in the content of these substances. The analysis of enzymes involved in proline metabolism revealed the glutamate as a precursor of proline synthesis in PEG-induced stress conditions. The increase in the activity of antioxidative enzymes, especially catalase and peroxidases, was characteristic for tolerant wheat plants, but for sensitive ones, a decrease in superoxide dismutase and an increase in mainly glutathione reductase activities were observed. After NaCl-treatment smaller changes of all biochemical parameters were registered in comparison with PEG-induced stress. Exceptions were the higher values of ethylene content and a significant increase in saccharose, raffinose and maltose levels (only in stress sensitive plants). The proline synthesis pathway was stimulated from both glutamate and ornithine precursors. These results suggest that the accumulation of inorganic ions in NaCl-stressed plants may be involved in protective mechanisms as an additional osmoregultor. Thus, a weaker stressogenic effect as determined as water deficit by leaf relative water content and relative dry weight increase rate and differences in metabolite synthesis in comparison with PEG stress was observed. Proline seems to be the most important osmo-protector in osmotic stress initiated by both PEG and NaCl. The synthesis of sugars and PAs may be stimulated in a stronger stress conditions (PEG).