活性氧在UV-B诱导的玉米幼苗叶片乙烯产生中的作用

 研究了活性氧在UV-B(280～320 nm)诱导的玉米(Zea mays)幼苗叶片乙烯合成中的作用。结果表明,UV-B促进了玉米幼苗活性氧和乙烯的产生;乙 烯合成抑制剂氨氧乙烯基甘氨酸 (AVG)和氨氧乙酸(AOA)能明显减弱UV-B对玉米幼苗乙烯产生的诱导作用,但对活性氧(ROS)的 产生没有明显影 响;ROS的清除剂不但能抑制UV-B诱导的 ROS的产生,而且还可以抑制UV_B诱导的乙烯的产生,但这种抑制作用可以被外源O₂^.-的供体所逆转。这 说明,乙烯的积累不能作为UV-B胁迫下ROS的诱导的因素,相反,ROS的积累则导致了乙烯的积累;因此,ROS可能参与了UV-B胁迫诱导的乙烯的产生 。质膜NADPH氧化酶的抑制剂二苯碘鎓(DPI)和H₂O₂的特异性清除剂过氧化氢酶（CAT）对UV-B胁迫诱导的乙烯积累 几乎没有影响, 这说明H₂O₂ 可能与UV-B诱导的玉米幼苗叶片乙烯的产生无关, 在UV-B诱导的玉米幼苗叶片乙烯的生物合成过程中O₂^.-起着很重要的作用,相关的O₂^.-不是由 NADPH氧化酶催化产生的。     

外源亚精胺和精胺对NaHCO3胁迫下南蛇藤抗氧化系统的影响

研究了叶面喷施亚精胺和精胺对NaHCO₃胁迫下南蛇藤叶片抗氧化系统的影响.结果表明：外源亚精胺和精胺处理使NaHCO₃胁迫下南蛇藤叶片O₂^-·产生速率、H₂O₂、丙二醛(MDA)含量和电解质外渗率显著降低(P<0.05).亚精胺处理明显提高了盐胁迫下超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)等抗氧化酶的活性,以及还原型谷胱甘肽(GSH)、类胡萝卜素(CAR)和脯氨酸(Pro)等抗氧化剂的含量,但对还原型抗坏血酸(AsA)含量没有作用;精胺处理明显提高NaHCO₃胁迫下POD和APX的活性以及GSH、CAR和Pro的含量,但对SOD和AsA含量影响不显著,甚至引起CAT活性明显降低.亚精胺和精胺处理明显改善了NaHCO₃胁迫下南蛇藤的生长.外源亚精胺和精胺可以改善NaHCO₃胁迫下南蛇藤叶片的膜保护功能,减少叶片中活性氧的积累,从而提高南蛇藤对NaHCO₃胁迫的抗性.     

二氧化硫对小麦的氧化胁迫及其某些信号分子的调节

通过在密闭的培养箱中一次性通入不同体积浓度的SO₂气体,研究了小麦幼苗超氧自由基O2-含量和3种抗氧化酶活性的变化,探讨了信号分子水杨酸、乙烯和过氧化氢对SO₂氧化胁迫的调节作用.结果表明,当通入10和40 μl·L^-1 SO₂时,小麦叶片中O2-含量递增,过氧化物酶(POD)和过氧化氢酶(CAT)活性增强,但超氧化物歧化酶(SOD)活性降低.当SO₂浓度达到50 μl·L^-1时,POD和CAT活性也开始降低,此时叶片尖端出现坏死,叶片绿色部位滋生大量真菌.用1 mmol·L^-1水杨酸(SA)(pH6.5)浸泡小麦干种子6 h,或用10 mmol·L^-1 H₂O₂浸泡幼苗,O2-含量低于对照植株,而3种酶的活性高于对照植株,均可有效地减轻SO₂的氧化胁迫.在SO₂熏蒸下,乙烯显著抑制3种酶的活力,提高O2-的形成速率.SA与乙烯同时使用时,SA几乎完全消除了乙烯的负面作用.     

外源NO对盐胁迫下黑麦草幼苗活性氧代谢、多胺含量和光合作用的影响

采用溶液培养法研究了外源一氧化氮(nitric oxide,NO)供体硝普钠(sodium nitroprusside,SNP)对100 mmol·L^-1 NaCl胁迫下黑麦草幼苗生长、活性氧代谢、多胺含量和光合作用的影响。结果表明,50 μmol·L^-1 SNP显著提高盐胁迫下黑麦草幼苗叶片的超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及谷胱甘肽(GSH)、精胺(Spm)、亚精胺(Spd)含量和(Spm+Spd)/Put比值,降低了腐胺(Put)、超氧阴离子(O^—·₂)、H₂O₂和丙二醛(MDA)含量,使幼苗叶片叶绿素和类胡萝卜素含量、净光合速率(P_n)和气孔导度(G_s)升高,胞间CO₂浓度(C_i)下降,相对生长量增加。叶绿素荧光动力学资料显示,SNP处理降低盐胁迫下黑麦草叶片的初始荧光(F₀),表明它对光合膜系统具有保护效应。SNP处理不仅提高了盐胁迫下叶片的最大荧光(F_m)、PSⅡ潜在光化学效率(F_v/F₀)和PSⅡ最大光化学效率(F_v/F_m),而且提高了PSⅡ实际光化学效率(Φ_PSⅡ)、光化学荧光猝灭系数(q_P)、表观光合电子传递速率(ETR)和光化学速率(PCR),降低了非光化学荧光猝灭系数(NPQ)和天线热耗散(D),而1 mmol·L^-1 NO清除剂PTIO和0.5 μmol·L^-1 NaNO₂处理(对照)则无此效应。由此表明,外源NO可能通过提高植株的抗氧化能力及光能的捕获与转换而增强盐胁迫下黑麦草叶片的光合能力,从而缓解盐胁迫对幼苗生长的抑制作用。     

干旱胁迫下多裂骆驼蓬(Peganum multisectum Bobr)叶片乙烯释放和多胺含量变化与活性氧积累的关系

通过盆栽土培试验研究了干旱胁迫下多裂骆驼蓬(Peganum multisectum Bobr)叶片乙烯释放、多胺含量、活性氧水平及细胞膜透性的动态变化.结果表明,随着土壤干旱强度的增加和胁迫时间的延长,多裂骆驼蓬叶片内丙二醛(MDA)含量和细胞膜透性呈递增变化趋势;轻度胁迫下,乙烯产生速率、多胺(Put、Spm、Spd)、活性氧(O2-·、H2O2)和MDA含量及多胺氧化酶(PAO)活性随胁迫时间延长无明显变化;中度和重度胁迫初期(胁迫后0～30d)腐胺(Put)、精胺(Spm)和亚精胺(Spd)含量快速提高,乙烯生成速率下降,而O2-·、H2O2、MDA含量和PAO活性相对平稳;胁迫后期(胁迫后45～75d)乙烯生成速率增高,Put、Spm和Spd含量下降, O2-·、H2O2和MDA含量大幅度增加,膜透性增大,且乙烯释放与O2-·、H2O2含量呈显著正相关.表明中度和重度胁迫下多裂骆驼蓬叶片存在乙烯和多胺合成的相互制约,乙烯释放增加诱导活性氧积累导致膜透性急剧增大.     

黄瓜幼苗对氯化钠和碳酸氢钠胁迫的生理响应差异

采用营养液培养方法,分别用不同浓度（0、25、50和75 mmol·L^-1）的NaCl和NaHCO₃对黄瓜幼苗进行胁迫处理,研究黄瓜幼苗对NaCl和NaHCO₃胁迫的生理响应差异.结果表明：随着胁迫强度的增加,黄瓜植株地上部和地下部生长量、叶片叶绿素含量和相对含水量均呈明显下降趋势,但NaHCO₃处理下降幅度大于NaCl处理.随着处理浓度的增加,黄瓜地上部Na⁺含量显著上升,K⁺含量显著下降,在相同的Na⁺浓度下,NaHCO₃处理比NaCl处理下降幅度更大,具有更低的K⁺/Na⁺.与NaCl处理相比,NaHCO₃处理的黄瓜叶片电解质渗漏率、丙二醛、脯氨酸和可溶性糖含量增加幅度更大.NaCl和NaHCO₃处理使黄瓜叶片超氧化物歧化酶、抗坏血酸过氧化物酶和脱氢抗坏血酸还原酶活性受到显著诱导,而使过氧化物酶活性受到明显抑制.     

硝普钠缓解镧引起的黑麦草幼苗生长抑制和根系氧化损伤

采用水培方法,研究了外源一氧化氮（NO）供体硝普钠（SNP）对300 μmol·L^-1 LaCl₃胁迫下黑麦草幼苗生长和根系活性氧代谢的影响。结果表明：在LaCl₃胁迫下,喷施50 μmol·L^-1 SNP能够抑制镧（La）从黑麦草根系向地上部的转运,缓解La对幼苗生长的抑制作用;提高幼苗根系超氧化物歧化酶和抗坏血酸过氧化物酶活性,降低过氧化物酶活性及谷胱甘肽、脯氨酸、H₂O₂、丙二醛含量、超氧阴离子产生速率和质膜相对透性,对过氧化氢酶活性和抗坏血酸含量无显著影响。表明NO可通过活性氧代谢的调节,缓解高浓度La胁迫对黑麦草幼苗生长的抑制作用。     

Na2CO3胁迫下星星草幼苗活性氧及保护酶活性的变化

对低浓度Na₂CO₃胁迫下星星草幼苗相对电导率、O^-₂产生速率、H₂O₂含量以及保护酶CAT、SOD和POD活性的研究结果表明,低盐胁迫1 d后,星星草幼苗细胞膜的通透性、O^-₂产生速率、H₂O₂含量及保护酶活性都随着盐胁迫的加剧而升高,其具体的变化规律与盐胁迫强度和幼苗细胞膜的受损伤程度密切相关,但相关关系的性质上具有差异。     

碱胁迫对黑麦草幼苗根系活性氧代谢和渗透溶质积累的影响

为了探讨牧草对碱胁迫的耐受程度,采用营养液砂培方法,研究了不同浓度NaHCO3（0、50、100、150和200 mmol·L^-1）胁迫对黑麦草幼苗根系生长、活性氧代谢和渗透溶质积累的影响。结果表明：NaHCO3胁迫显著抑制黑麦草幼苗根系的生长,其抑制程度随胁迫浓度提高而增强,黑麦草可耐受的最高NaHCO₃浓度约为150 mmol·L^-1。随着NaHCO₃胁迫浓度的增加,黑麦草根中超氧阴离子(O^-·₂)、过氧化氢(H₂O₂)和丙二醛(MDA)含量明显上升,超氧化物歧化酶(SOD)活性和谷胱甘肽(GSH)含量显著下降,过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及抗坏血酸(ASA)含量先升后降。黑麦草根中Na⁺含量随NaHCO₃浓度增大而增加,K⁺含量和K⁺/Na⁺比降低,可溶性糖含量先升后降,脯氨酸含量则先降后升,游离氨基酸含量呈先升后降再升高变化。表明碱胁迫导致的活性氧代谢失调和Na⁺、K⁺失衡及积累有机溶质进行渗透调节时更多能量的消耗可能是黑麦草根系生长受抑的重要因素。     

(NH4)2SO4对瓜尔豆幼苗在不同光照下耐冷性的影响

通过温室穴盘育苗试验,研究叶面喷施(NH₄)₂SO₄对低温胁迫12 h后不同光通量密度（PFD）条件下,瓜尔豆幼苗在常温培养过程中幼苗生存及叶片SOD活性、POD活性和MDA含量的影响。结果表明：低温处理一夜后,在温室自然光照（强光）下进行常温恢复时,瓜尔豆叶片中SOD和POD活性始终显著低于对照,MDA含量显著高于对照,幼苗死亡率显著高于对照;在90 μmol·m^-2·s^-1弱光下恢复2～4 d后,叶片中保护酶活性显著高于对照,MDA含量保持较低水平,幼苗均正常生长。叶面喷施(NH₄)₂SO₄能显著提高低温处理后的植株叶片抗氧化酶类活性,减少叶片中MDA的产生,降低幼苗死亡率,0.2% (NH₄)₂SO₄处理效果最好,其次为0.4%(NH₄)₂SO₄。短期低温后,使植物处在弱光环境下能减少活性氧的发生,为植物抗氧化系统达到新的平衡提供有利条件,从而减轻甚至消除低温伤害。     

干旱胁迫对杨树幼苗生长、光合特性及活性氧代谢的影响

2011年4-10月在山东省林业科学研究院试验苗圃,选取欧美I-107杨扦插苗为试材,采用盆栽控水试验,研究了不同水分处理(正常水分、轻度干旱、中度干旱和重度干旱)对杨树幼苗生长和气体交换、叶绿素荧光特性、活性氧代谢的影响.结果表明: 与正常水分处理相比,轻度、中度和重度干旱胁迫下的地径生长量分别下降12.8%、44.5%和65.6%,苗高生长量分别下降12.2%、43.1%和57.2%;随着胁迫强度的增加和胁迫时间的延长,杨树幼苗叶片的PSⅡ光能转化效率、实际量子产量、光化学猝灭系数、净光合速率和气孔导度在轻度胁迫下缓慢下降,而在中度和重度胁迫下迅速下降;非光化学猝灭系数在轻度胁迫下显著升高,而在中度和重度胁迫下先升高后降低;叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均先升高后降低,但对干旱胁迫和活性氧的响应存在一定差异;叶片相对电导率、丙二醛含量显著增加,质膜受损,大量离子外渗,且重度胁迫下质膜的损害最严重.轻度干旱胁迫下,I-107杨树幼苗具有较高的光合效率和较强的抗氧化保护酶系统;而中度和重度干旱下,其光合效率显著下降,抗氧化保护酶系统明显遭到破坏.     

Brassinolide alleviates the drought-induced adverse effects in barley by modulation of enzymatic antioxidants and ultrastructure

In the present study, possible role of exogenously applied brassinolide (BL) in alleviating the detrimental effects of polyethylene glycol (PEG)-inducted drought stress in barley was evaluated. Barley seedlings were subjected to two PEG levels (0 and 8% w/v) for 2 weeks followed by a foliar spray of BL (0, 0.01, 0.1 and 1 µM) to assess the changes in growth, gas exchange, chlorophyll contents, antioxidant enzyme activities and ultrastructural changes. PEG-induced drought considerably inhibited the barley growth in terms of shoot and root length, shoot, root fresh and dry weights, and chlorophyll contents. Moreover, extensive decrease by PEG-induced drought in gas exchange attributes i.e. net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO₂ were also recorded. However, exogenous application of BL remarkably improved the gas exchange attributes, chlorophyll contents and plant growth under either drought or control condition. Furthermore, foliar spray of BL decreased the production of malondialdehyde (MDA) and reactive oxygen species (ROS) in the leaves and roots by increasing enzymatic antioxidant activities under drought stress. The microscopic examination indicated that exogenous application of BL improved the cell structure and enabled a clean mesophyll cell having a well-developed chloroplast with thylakoid membranes of the drought stressed plants. On the basis of these findings, it can be concluded that exogenous application of BL could alleviate drought stress to barley by ameliorating photosynthetic parameters, improving antioxidants enzyme activities, reducing ultrastructural changes in leaf mesophyll and finally maintaining the plant growth.     

Physiological regulation of seed soaking with soybean isoflavones on drought tolerance of Glycine max and Glycine soja

In this study, the Glycine max Jackson cultivar (the relatively drought-sensitive) and the Glycine soja BB52 accession (the drought-tolerant one) were used as the experimental materials. Effects of seed soaking with exogenous soybean isoflavones (daidzin or genistin) on seed germination, and seedlings photosynthesis, relative electrolytic leakage, content of thiobarbituric acid reactive substances , and anti-oxidative activities were investigated under drought stress conditions. The results showed that, treatments of seed soaking with daidzin or genistin could improve seed germination, and alleviate cell damage, enhance anti-oxidative activities and photosynthesis in drought-stressed seedlings, therefore displayed mitigated effects on soybean drought injury, especially for the drought-sensitive G. max Jackson cultivar. Thus seed soaking with exogenous soybean isoflavones may be a usable approach to enhance drought tolerance of cultivated soybean in practice.     

Ethylene glycol tetra-acetic acid and salicylic acid improve anti-oxidative ability of maize seedling leaves under heavy-metal and polyethylene glycol 6000-simulated drought stress

Stress caused by divalent heavy metal ions and drought exert many toxic and adverse effects on seedling growth and development of plants, especially on leave growth. Organic acids such as ethylene glycol tetra-acetic acid (EGTA) and salicylic acid (SA) have been shown to alleviate the unfavorable effects exerted by these stresses on seedling growth and metabolism. In order to reveal the physiological mechanism underlying these toxic effects and the alleviated effects exerted by organic acids, maize seedling leaves (genotype “Zhengdan958”) were exposed for 7 days to different concentrations of cadmium (Cd²⁺), mercury (Hg²⁺), and lead (Pb²⁺) ions and to the drought stress-inducing polymer polyethylene glycol (PEG) 6000. The same experiments were also carried out in the presence of EGTA or SA. Treated leaves were analyzed for activities of the anti-oxidative enzymes catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) and for the content of malondialdehyde (MDA). The results showed that stress treatments with the heavy metals Cd²⁺, Hg²⁺, and Pb²⁺ and with PEG all affected the activities of CAT, POD, and SOD, although the extent and patterns of these changes were different under different stress conditions. Both heavy metal and drought stress caused a concentration-dependent increase in MDA content. Treatments in the presence with EGTA or SA showed that both these compounds exerted certain alleviative effects on seedling growth under Cd²⁺, Hg²⁺, and Pb²⁺ stresses and PEG-simulated drought stress, with SA generally showing better effects than EGTA.     

水杨酸对冷胁迫下香蕉幼苗抗冷性的效应

用0.6 mmol/L水杨酸(SA)喷洒香蕉幼苗叶片1 d后,于8℃低温胁迫5 d,研究水杨酸对香蕉幼苗抗冷性的影响。结果表明:SA降低了受低温胁迫的香蕉幼苗叶片相对电导率及丙二醛(MDA)和过氧化氢含量,减缓了可溶性蛋白质含量的下降,提高了脯氨酸含量及过氧化物酶(POD)、过氧化氢酶(CAT)活性。表明SA可通过提高香蕉幼苗抗氧化酶活性、清除活性氧的积累、减少膜损伤来缓解低温对香蕉幼苗的损伤。     

Different drought-stress responses in photosynthesis and reactive oxygen metabolism between autotetraploid and diploid rice

Photosynthetic light curve, chlorophyll (Chl) content, Chl fluorescence parameters, malondialdehyde (MDA) content, phosphoenolpyruvate carboxylase (PEPC) activity and reactive oxygen metabolism were studied under drought stress in two autotetraploid rice lines and corresponding diploid rice lines. Net photosynthetic rate decreased dramatically, especially under severe drought stress and under high photosynthetic active radiation in diploid rice, while it declined less under the same conditions in autotetraploid lines. Compared with the corresponding diploid lines, the Chl content, maximum photochemical efficiency of photosystem (PS) II, and actual photochemical efficiency of PSII were reduced less in autotetraploid lines. PEPC activities were higher in autotetraploid rice lines. PEPC could alleviate inhibition of photosynthesis caused by drought stress. The chromosome-doubling enhanced rice photoinhibition tolerance under drought stress. The lower MDA content and superoxide anion production rate was found in the autotetraploid rice indicating low peroxidation level of cell membranes. At the same time, the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities were higher in autotetraploid rice lines. SOD, POD, and CAT could effectively diminish the reactive oxygen species and reduced the membrane lipid peroxidation.     

高温干旱复合胁迫对构树幼苗抗氧化酶活性和活性氧代谢的影响

近年来,全球气温不断升高,亚热带部分地区夏季高温和临时性干旱现象日益显著,高温与干旱严重威胁着植物的生存与生长。采用盆栽和人工气候室方式模拟不同的温度和土壤水分梯度,研究了高温与干旱复合胁迫对构树幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)与过氧化氢酶(CAT)活性、活性氧代谢和丙二醛(MDA)含量的影响。结果表明:(1)高温或干旱单一胁迫下,构树幼苗SOD、POD、CAT活性增加,复合胁迫下,SOD和POD酶活性高于单一胁迫,且随着复合胁迫时间延长而升高。SOD活性受温度和土壤水分双因素影响极其显著,复合胁迫对SOD活性有一定程度的叠加效应;(2)复合胁迫下,活性氧代谢物与MDA含量均显著高于单一胁迫,表明复合胁迫加剧对植物的伤害。通过改变抗氧化酶活性以减轻膜脂过氧化的伤害作用是有限的。     

干旱胁迫对大豆苗期生长发育和生理生态特征的影响

对土壤逐步干旱下大豆幼苗形态特征和生理生态特征的变化研究表明:随着胁迫强度的增加,大豆苗期的光合速率、蒸腾速率、气孔导度降低,且相互之间呈显著正相关;随着胁迫时间的延长,叶绿素含量和叶片含水量呈低-高-低的变化趋势;在胁迫初期,对干物质分配率的影响很小,随着胁迫时间的增加,差异越来越大;随着干旱胁迫天数和强度的增加,游离脯氨酸含量呈逐渐递增的趋势,尤其是重度胁迫下积累能力更强。     

高温胁迫下外源褪黑素对黄瓜幼苗活性氧代谢的影响

以黄瓜品种‘津春4号’为试材,用叶面喷施的方法,研究了高温胁迫条件下外源褪黑素(melatonin,MT)对黄瓜幼苗活性氧（ROS）代谢的影响.结果表明：外源MT能显著降低高温胁迫下黄瓜叶片超氧阴离子自由基（O₂^-.）产生速率、过氧化氢（H₂O₂）含量、电解质漏渗率（relative electric conductivity, REC）及丙二醛(MDA)含量,增强黄瓜幼苗叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性,提高抗坏血酸（AsA）、谷胱甘肽（GSH）及可溶性蛋白质含量.说明MT预处理能抑制高温胁迫条件下黄瓜幼苗体内ROS的产生,提高抗氧化酶系的活性及抗氧化物质的含量,降低膜质过氧化水平,保护脂膜的完整性,减少电解质的外渗,减轻高温胁迫对幼苗造成的伤害,提高幼苗抗高温胁迫的能力.