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。     

Effect of Drought Stress on Lipid Peroxidation,Osmotic Adjustment and Antioxidant Enzyme Activity of Leaves and Roots of <Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr. Seedling

Seedling stage is a critical period for survival and growth under drought stress. In the current study, we determined effects of drought stress on physiological and biochemical parameters of leaves and roots of Lycium ruthenicum Murr. seedling. The variables measured were lipid peroxidation (in terms of malondialdehyde (MDA) content), osmotic substances (free proline, soluble protein, and soluble sugar), and antioxidative enzymes (peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT)). Free proline, soluble sugar, and MDA of leaves and roots increased with increasing stress level. Leaves displayed higher accumulations of free proline and MDA than roots. However, roots showed higher total soluble sugar than leaves. Under drought stress, soluble proteins in leaves and roots decreased initially and then increased. Meanwhile, measured proteins were higher in leaves. Under drought stress, SOD, POD, and CAT activities in leaves increased initially and then decreased but increased with increasing drought stress level in roots. Under drought the level of accumulation of osmotics was higher in the leaves than in the roots, while increased activity of antioxidant enzymes persisted in the stressed roots longer that in the leaves.     

Salicylic acid alleviates mercury toxicity by preventing oxidative stress in roots of Medicago sativa

Salicylic acid (SA) as a signal molecule mediates many biotic and environmental stress-induced physiological responses in plants. In this study, we investigated the role of SA in regulating Hg-induced oxidative stress in the roots of alfalfa (Medicago sativa). Plants pretreated with 0.2 mM SA for 12 h and subsequently exposed to 10 μM Hg²⁺ for 24 h displayed attenuated toxicity to the root. The SA-promoted root growth was correlated with decreased lipid peroxidation in root cells. The ameliorating effect of SA was confirmed by the histochemical staining for the detection of loss of membrane integrity in Hg-treated roots. We show that treatment with 0.2 mM SA increased the activity of NADH oxidase, ascorbate peroxidase (APX) and peroxidase (POD) in the roots exposed Hg. However, a slightly decreased superoxide dismutase (SOD) activity was observed in SA + Hg-treated roots when compared to those of Hg treatment alone. We also measured accumulation of ascorbate (ASC), glutathione (GSH) and proline in the roots of alfalfa and found that roots treated with SA in the presence of Hg accumulated more ASC, GSH and proline than those treated with Hg only. These results suggest that exogenous SA may improve the tolerance of the plant to the Hg toxicity.     

Effects of water-deficit stress and paclobutrazol on growth,relative water content,electrolyte leakage,proline content and some antioxidant changes in Curcuma alismatifolia Gagnep. cv. Chiang Mai Pink

Effects of water-deficit stress and paclobutrazol (PBZ) on the physiological and biochemical changes in Curcuma alismatifolia Gagnep. cv. Chiang Mai Pink (Zingiberaceae) were investigated. One hundred rhizomes were grown for 30–35 days and then divided into the following 4 treatments: (1) well-watered, (2) not watered, (3) well-watered and treated with 1500 ppm PBZ being applied once to the soil, and (4) not watered but treated with 1500 ppm PBZ. After 50 days of growth, watering was withheld for 30 days. After water stress was initiated, plant height, plant fresh weight, soil water content, relative water content (RWC), electrolyte leakage (EL), proline content, vitamin C and E content, as well as the activities of catalase (CAT) and superoxide dismutase (SOD) in the leaves were determined every 10 days. The results showed that water-deficit stress decreased plant height and plant fresh weight, whereas this stress and PBZ did not result in a decrease in these parameters. Water stress reduced RWC, but induced EL and proline content in the leaves. However, the leaves showed opposite results when PBZ was added to the treatments. Some antioxidants such as vitamin C, vitamin E, and the activities of CAT and SOD were induced in the leaves by PBZ. Moreover, the content of vitamin C, vitamin E and CAT activity were higher in relation to water-deficit stress and PBZ treatments. This indicates that PBZ induced a number of some physiological and biochemical adaptations (maintaining growth and RWC, decreasing EL and proline content, increasing the vitamin C and vitamin E levels, and CAT and SOD activities) that enable the Curcuma plant to tolerate drought.     

Modulation of antioxidant enzyme activities and metabolites ratios by nitric oxide in short-term salt stressed soybean root nodules

Several abiotic factors cause molecular damage to plants either directly or through the accumulation of reactive oxygen species such as hydrogen peroxide (H₂O₂). We investigated if application of nitric oxide (NO) donor 2,2′-(hydroxynitrosohydrazono) bis-ethanimine (DETA/NO) could reduce the toxic effect resulting from short-term salt stress. Salt treatment (150 mM NaCl) alone and in combination with 10 μM DETA/NO or 10 μM DETA were given to matured soybean root nodules for 24 h. Salt stress resulted in high H₂O₂ level and lipid peroxidation while application of DETA/NO effectively reduced H₂O₂ level and prevented lipid peroxidation in the soybean root nodules. NO treatment increased the activities of ascorbate peroxidase and dehydroascorbate reductase under salt stress. Whereas short-term salt stress reduced AsA/DHAsA and GSH/GSSG ratios, application of the NO donor resulted in an increase of the reduced form of the antioxidant metabolites thus increasing the AsA/DHAsA and GSH/GSSG ratios. Our data suggests a protective role of NO against salt stress.     

不同沙地共有种沙生植物对环境的生理适应机理

选择3个温带沙地(松嫩沙地、呼伦贝尔沙地、科尔沁沙地)4个共有种沙生植物(黄柳(Salix gordejevii)、差巴嘎蒿(Artimisia halodendron)、扁蓿豆(Melissitus ruthenica),猪毛菜(Salsola collina),通过自然状况下其叶片抗氧化酶活力和渗透调节物及丙二醛(MDA)含量日变化分析,探讨抗氧化酶活力和渗透调节物在沙生植物适应沙漠环境强光辐射和温度日变化中的作用,以及不同科属沙生植物抗逆生理调控机理的差异。结果表明:(1)不同沙地的4个共有沙生植物种可通过自身快速生理代谢调解,积累渗透调节物、提高抗氧化酶活力应对沙漠环境强光辐射和温度日变化,但生理调控幅度较小。(2)3个沙地不同科属的4个共有种在渗透调节物含量和抗氧化酶活力及种类上存在差异。扁蓿豆叶片日均MDA含量、POD(peroxidase)活力、CAT(catalase)活力、脯氨酸含量均最高,分别较其它3个种平均高2、10、2和2.5倍。黄柳叶片日均MDA含量较高,SOD(superoxide dismutase)活力和可溶性糖含量最高,分别较其它3个种高1.2和3倍。差巴嘎蒿和猪毛菜叶内MDA含量较低,POD、CAT、SOD活力和脯氨酸、可溶性糖含量均最低。沙生植物细胞中膜脂过氧化程度和抗氧化酶活力及渗透调节物含量呈正相关。自然状况下3个沙地的扁蓿豆和黄柳通过生理代谢调节维持细胞水分和氧自由基代谢平衡适应沙漠环境,差巴嘎蒿和猪毛菜依靠特殊的叶片形态结构变异减少光辐射吸收、降低水分蒸腾、维持叶片水分平衡、降低细胞膜脂过氧化。因此不同科属沙生植物维持叶片水分和氧自由基代谢平衡可能是其适应沙漠环境生存的重要生理调控机理。由于不同科属沙生植物种对沙漠环境适应的生理调节机理的不同,在未来农作物、林木抗逆育种中,根据具体科属植物选择合适的沙生植物作为亲本对提高抗逆育种效率是十分重要的。     

丛枝菌根真菌对盐胁迫下黄瓜幼苗渗透调节物质含量和抗氧化酶活性的影响

以盐敏感型黄瓜品种‘津春2号’为材料,研究了丛枝菌根真菌(AMF)对盐胁迫下黄瓜幼苗生长及叶片、根系中渗透调节物质含量和抗氧化酶活性的影响.结果表明:(1)在盐胁迫条件下,黄瓜幼苗生长受到明显抑制,其株高、地上部、地下部干鲜重均明显减小,同时体内可溶性蛋白、可溶性糖、脯氨酸和MDA含量,以及O2(÷)产生速率和SOD、POD、CAT活性均比对照显著升高.(2)盐胁迫下接种AMF可显著促进黄瓜植株的生长,进一步提高黄瓜幼苗体内可溶性蛋白、可溶性糖和脯氨酸含量及SOD、POD、CAT活性,而显著降低MDA含量和O2(÷)产生速率.研究表明,AMF可通过显著促进盐胁迫下黄瓜幼苗体内渗透调节物质积累和抗氧化酶活性提高,有效降低体内膜脂过氧化水平,从而缓解盐胁迫对植株的伤害,增强黄瓜幼苗对盐胁迫的耐性.     

海滨沙滩单叶蔓荆对沙埋的生理响应特征

海滨沙滩单叶蔓荆(Vitex trifolia L.var.simplicifolia)是优良的抗沙埋地被植物.以烟台海岸沙地单叶蔓荆为材料,通过不同厚度沙埋过程中沙上和沙下叶片抗逆生理指标的测定以揭示其抗沙埋生理调控机制.结果表明,轻度和中度沙埋5d,成株和幼株整株叶片细胞膜透性增大、POD和SOD活力增高、MDA和脯氨酸含量和叶片相对含水量(RWC)增加、可溶性糖含量下降.但同株沙上叶片细胞膜透性、MDA含量、SOD和POD活力和可溶性糖含量均高于沙下,而沙上叶片脯氨酸含量低于沙下叶片.在轻度和中度沙埋lOd,沙上叶片细胞膜透性、MDA和可溶性糖含量、叶片POD活力降低,叶片SOD活力仍有小幅度增高,但脯氨酸含量增加,沙上叶片生长旺盛.研究表明,沙埋下叶片抗氧化酶活力和脯氨酸含量与细胞膜透性和膜脂过氧化成正相关.沙埋使植株上部叶片接近沙表面而经受干旱和地面热辐射胁迫引起细胞膜脂过氧化加剧和细胞膜透性加大.同时沙埋也使沙下叶片遭遇黑暗和缺氧胁迫诱导细胞内膜脂过氧化,但也激活了叶片抗氧化酶保护系统和叶片脯氨酸的积累抑制细胞膜脂过氧化维护细胞膜的稳定.因此在沙埋过程中,叶片快速响应沙埋胁迫激活叶片抗氧化酶系统抑制膜脂过氧化作用维持氧自由基和抗氧化酶系统的动态平衡在单叶蔓荆适应轻度和中度沙埋,维护沙上叶片旺盛生长中起重要作用,也是重度全埋下沙下植株茎顶端能快速延伸弯曲生长最后顶出沙面再生的主要生理保护原因.     

Adaptability to drought in sugar beet cultivars

The effects of NaCl and polyethylene glycol (PEG) on superoxide dismutase (SOD) and peroxidase (P) activities, lipid peroxidation (LP) and proline content in seeds and leaves of drought tolerant (FC-506 and MS-100) and drought sensitive (MS-612 and MS-13) sugar beet cultivars were examined. After PEG and NaCl treatment in tolerant cultivars both in seeds and leaves SOD activity mainly increased, though P activity increased only in leaves of tolerant cultivars. In drought sensitive cultivars the decrease of SOD and P activity was mostly observed. LP increased in seeds and leaves of all examined cultivars. The proline content increased in the leaves of examined cultivars and was significantly higher in drought tolerant plants. On the other hand, in the seeds only slight increase in proline content was found. The results obtained indicated that drought tolerance could be correlated with high proline content and enzymatic defense against lipid peroxidation.     

Effect of long-term salinity on cellular antioxidants,compatible solute and fatty acid profile of Sweet Annie (Artemisia annua L.)

Impact of long-term salinity and subsequent oxidative stress was studied on cellular antioxidants, proline accumulation and lipid profile of Artemisia annua L. (Sweet Annie or Qinghao) which yields artemisinin (Qinghaosu), effective against cerebral malaria-causing strains of Plasmodium falciparum. Under salinity (0.0–160 mM NaCl), in A. annua, proline accumulation, contents of ascorbate and glutathione and activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) increased, but the contents of reduced forms of glutathione (GSH) and ascorbate declined. The fatty-acid profiling revealed a major salinity-induced shift towards long-chain and mono-saturated fatty acids. Myristic acid (14:0), palmitoleic acid (16:1), linoleic acid (18:2) and erucic acid (22:1) increased by 141%, 186%, 34% and 908%, respectively, in comparison with the control. Contents of oleic acid (18:1), linolenic acid (18:3), arachidonic acid (22:0) and lignoceric acid (24:0) decreased by 50%, 17%, 44% and 78%, respectively. Thus, in A. annua, salinity declines ascorbate and GSH contents. However, increased levels of proline and total glutathione (GSH + GSSG), and activities of antioxidant enzymes might provide a certain level of tolerance. Modification in fatty-acid composition might be a membrane adaptation to long-term salinity and oxidative stress.     

外源甲基乙二醛对干旱胁迫下板栗幼苗的影响

甲基乙二醛(MG)是一种在植物中具有多种功能的新型信号分子.为探究MG对板栗幼苗干旱胁迫的影响,以两年生'黄棚'板栗幼苗为试材,通过聚乙二醇(PEG)模拟干旱胁迫并进行MG及其清除剂N-乙酰半胱氨酸(NAC)处理,分析板栗幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(...     

Kolaviron,a biflavonoid complex of Garcinia kola seeds modulates apoptosis by suppressing oxidative stress and inflammation in diabetes-induced nephrotoxic rats

Diabetic nephropathy is a complex disease that involves increased production of free radicals which is a strong stimulus for the release of pro-inflammatory factors. We evaluated the renal protective effect of kolaviron (KV) – a Garcinia kola seed extract containing a mixture of 5 flavonoids, in diabetes-induced nephrotoxic rats. Male Wistar rats were divided into 4 groups: untreated controls (C); normal rats treated with kolaviron (C + KV); untreated diabetic rats (D); kolaviron treated diabetic rats (D + KV). A single intraperitoneal injection of streptozotocin (STZ, 50 mg/kg) was used for the induction of diabetes. Renal function parameters were estimated in a clinical chemistry analyzer. Markers of oxidative stress in the kidney homogenate were analyzed in a Multiskan Spectrum plate reader and Bio-plex Promagnetic bead-based assays was used for the analysis of inflammatory markers. The effect of kolaviron on diabetes-induced apoptosis was assessed by TUNEL assay. In the diabetic rats, alterations in antioxidant defenses such as an increase in lipid peroxidation, glutathione peroxidase (GPX) activity and a decrease in catalase (CAT) activity, glutathione (GSH) levels and oxygen radical absorbance capacity (ORAC) were observed. There was no difference in superoxide dismutase (SOD) activity. Diabetes induction increased apoptotic cell death and the levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α with no effect on IL-10. Kolaviron treatment of diabetic rats restored the activities of antioxidant enzymes, reduced lipid peroxidation and increased ORAC and GSH concentration in renal tissues. Kolaviron treatment of diabetic rats also suppressed renal IL-1β. The beneficial effects of kolaviron on diabetes-induced kidney injury may be due to its inhibitory action on oxidative stress, IL-1β production and apoptosis.     

Antioxidant responses to water deficit by drought‐tolerant and ‐sensitive sugarcane varieties

Water deficit is the major yield‐limiting factor of crop plants. The exposure of plants to this abiotic stress can result in oxidative damage due to the overproduction of reactive oxygen species. The aim of this work was to study the antioxidant‐stress response of drought‐tolerant (SP83‐2847 and SP83‐5073) and drought‐sensitive (SP90‐3414 and SP90‐1638) sugarcane varieties to water‐deficit stress, which was imposed by withholding irrigation for 3, 10 and 20 days. The drought‐sensitive varieties exhibited the lowest leaf relative water content and highest lipid peroxidation, hydrogen peroxide (H₂O₂) and proline contents during the progression of the drought‐stress condition. The antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPOX) and glutathione reductase (GR) activities changed according to variety and stress intensity. SP83‐2847 exhibited higher CAT and APX activities than the other varieties in the early stage of drought, while the activities of GPOX and GR were the highest in the other varieties at the end of the drought‐stress period. A Cu/Zn SOD isoenzyme was absent at the end of drought period from the SP90‐3414‐sensitive variety. The results indicate that lipid peroxidation and early accumulation of proline may be good biochemical markers of drought sensitivity in sugarcane.     

Changes of antioxidative enzymes,lipid peroxidation and chlorophyll content in chickpea types colonized by different <Emphasis Type="Italic">Glomus</Emphasis> species under drought stress

In order to investigate the effects of Glomus species on some physiological characteristics of two chickpea types (Pirouz cultivar of Desi type and ILC-482 of Kabuli type) under non-stress (NS) and drought stress, an experiment was conducted using a factorial arrangement based on completely randomized design with three replications. Drought stress decreased shoot and total dry weight in plants. However inoculation of plants with mycorrhiza improved these traits. Leaf chlorophyll content was decreased, but leaf proline content and guaiacol peroxidases (EC 1.11.1.7) (POD), catalase (EC 1.11.1.6) (CAT), and ascorbate peroxidase (EC 1.11.1.11) (APX) activities were increased as a result of drought stress. Drought stress had no significant effect on soluble protein content and polyphenol oxidase (EC 1.10.3.1) (PPO) enzymatic activity in chickpea plants. In general, drought stress and especially severe drought stress increased membrane lipid peroxidation (MDA) in chickpea plants, which was more evident in non-inoculated than in inoculated plants. Inoculation of chickpea by AM significantly increased POD and PPO activities compared with non-inoculated chickpea, but had no effect on CAT activity and proline content of leaves. The reaction of chickpea cultivars to inoculation by AM species and irrigation levels were different. ILC-482 showed that antioxidant enzymes activities were more and thus less MDA compared with Pirouz cultivar. In general, the most POD and PPO activities were recorded for inoculated plants with G. etunicatum and G. versiform species, and the most APX activity was observed in plants inoculated with G. intraradices.     

Water stress induced changes in concentrations of proline and total soluble sugars in nodulated alfalfa (Medicago sativd) plants

Susceptibility of alfalfa ( Medicago saliva L. cv. Aragón) nodules and leaves to water stress has been investigated. Nodule acetylene reduction activity (ARA), leaf CO₂ exchange rate (CER) as well as soluble protein, proline and total soluble sugar (TSS) contents were determined during drought. Water status was estimated as water potential (Ψ_w) and Relative water content (RWC) of the respective tissues. Maximum rates of ARA required higher Ψ_w than CER. Nodules had lower RWC for a given Ψ_w than leaves. Water stress reduced soluble protein content in both tissues; however, the decline in soluble protein content was detected at greater Ψ_w in nodules than in leaves. Proline and TSS increased in leaves and nodules, and again the threshold Ψ_w triggering such accumulation was higher in nodule tissues. Oior results suggest that alfalfa nodules are more susceptible to water shortage than leaves. Effects of accumulated TSS and proline upon leaf and nodule physiology are discussed in relation to protein stability (proline), pH control (proline) and osmotic adjustment (proiine and TSS). The TSS accumulation induced by water stress suggests that substrate shortage would not be the primary effect of drought on nodule activity.     

Comparative lipid peroxidation,antioxidant defense systems and proline content in roots of two rice cultivars differing in salt tolerance

The changes in the activity of antioxidant enzymes such as superoxide dismutase (SOD: EC 1.15.1.1), catalase (CAT: EC 1.11.1.6), peroxidase (POX: EC 1.11.1.7), ascorbate peroxidase (APOX: EC 1.11.1.11) and glutathione reductase (GR: EC 1.6.4.2), free proline content, and the rate of lipid peroxidation level in terms of malondialdehyde (MDA) in roots of two rice cultivars (cvs.) differing in salt tolerance were investigated. Plants were subjected to three salt treatments, 0, 60, and 120 mol m⁻³ NaCl for 7 days. The results showed that activated oxygen species may play a role in cellular toxicity of NaCl and indicated differences in activation of antioxidant defense systems between the two cvs. The roots of both cultivars showed a decrease in GR activity with increase in salinity. CAT and APOX activities increased with increasing salt stress in roots of salt-tolerant cultivar Pokkali but decreased and showed no change, respectively, in roots of IR-28 cultivar. POX activity decreased with increasing NaCl concentrations in salt-tolerant Pokkali but increased in IR-28. SOD activity showed no change in roots of both cultivars under increasing salinity. MDA level in the roots increased under salt stress in sensitive IR-28 but showed no change in Pokkali. IR-28 produced higher amount of proline under salt stress than in Pokkali. Increasing NaCl concentration caused a reduction in root fresh weight of Pokkali and root dry weight of IR-28. The results indicate that improved tolerance to salt stress in root tissues of rice plants may be accomplished by increased capacity of antioxidative system.     

Effect of drought on biomass, protein content, lipid peroxidation and antioxidant enzymes in two sesame cultivars

The effects of drought on growth, protein content, lipid peroxidation, superoxide dismutase (SOD), peroxidase (POX), catalase (CAT) and polyphenol oxidase (PPO) were studied in leaves and roots of Sesamum indicum L. cvs. Darab 14 and Yekta. Four weeks after sowing, plants were grown under soil moisture corresponding to 100, 75, 50 and 25 % field capacity for next four weeks. Fresh and dry masses, and total protein content in leaves and roots decreased obviously under drought. However, several new proteins appeared and content of some proteins was affected. Measurement of malondialdehyde content in leaves and roots showed that lipid peroxidation was lower in Yekta than in Darab 14. Severe stress increased SOD, POX, CAT and PPO activities in leaves and roots, especially in Yekta. According to the present study Yekta is more resistant to drought than Darab 14.     

The effect of menadione-induced oxidative stress on the in vivo reactive oxygen species and antioxidant response system of Phanerochaete chrysosporium

The antioxidant response system of Phanerochaete chrysosporium against menadione-induced oxidative stress was investigated in this study. The superoxide anion radical levels in tested menadione-supplemented conditions generally decreased over the incubation period. The level of hydrogen peroxide and the activities of NAD(P)H oxidase, superoxide dismutase (SOD) and catalase (CAT) were higher than those in the controls at all incubation times. The highest NADH and NADPH oxidase activities were determined to be 4.9- and 5.0-fold higher than those in the control, respectively in cells exposed to 0.75 mM menadione. The SOD and CAT activities increased with increasing menadione, and their highest activities were 5.4- and 5.1-fold higher than those in the control, respectively. In 0.1–0.5 mM menadione exposed cells, the lipid peroxidation levels did not change significantly when compared to each other, except 8th hour of incubation (p > 0.01). Our result shows that although menadione induces the formation of reactive oxygen species, the antioxidant response system of P. Chrysosporium is able to negate menadione-induced oxidative stress up to relatively high menadione concentrations, as 0.75 mM. These results are important to determine the effects of menadione, as a medicine, on the antioxidant response system of eukaryotic models and the resulting level of damage.     

Influence of arbuscular mycorrhiza on lipid peroxidation and antioxidant enzyme activity of maize plants under temperature stress

The influence of the arbuscular mycorrhizal (AM) fungus, Glomus etunicatum, on characteristics of growth, membrane lipid peroxidation, osmotic adjustment, and activity of antioxidant enzymes in leaves and roots of maize (Zea mays L.) plants was studied in pot culture under temperature stress. The maize plants were placed in a sand and soil mixture under normal temperature for 6 weeks and then exposed to five different temperature treatments (5oC, 15oC, 25oC, 35oC, and 40oC) for 1 week. AM symbiosis decreased membrane relative permeability and malondialdehyde content in leaves and roots. The contents of soluble sugar content and proline in roots were higher, but leaf proline content was lower in mycorrhizal than nonmycorrhizal plants. AM colonization increased the activities of superoxide dismutase, catalase, and peroxidase in leaves and roots. The results indicate that the AM fungus is capable of alleviating the damage caused by temperature stress on maize plants by reducing membrane lipid peroxidation and membrane permeability and increasing the accumulation of osmotic adjustment compounds and antioxidant enzyme activity. Consequently, arbuscular mycorrhiza formation highly enhanced the extreme temperature tolerance of maize plant, which increased host biomass and promoted plant growth.