Mechanisms of exogenous nitric oxide and 24-epibrassinolide alleviating chlorosis of peanut plants under iron deficiency

Iron(Fe) is a crucial transition metal for all living organisms including plants; however, Fe deficiency frequently occurs in plant because only a small portion of Fe is bioavailable in soil in recent years. To cope with Fe deficiency, plants have evolved a wide range of adaptive responses from changes in morphology to altered physiology. To understand the role of nitric oxide(NO) and 24-epibrassinolide(EBR) in alleviating chlorosis induced by Fe deficiency in peanut(Arachis hypogaea L.) plants, we determined the concentration of chlorophylls, the activation, uptake, and translocation of Fe, the activities of key enzymes, such as ferric-chelate reductase(FCR),proton-translocating adenosine triphosphatase(H~+-ATPase), and antioxidant enzymes, and the accumulation of reactive oxygen species(ROS) and malondialdehyde(MDA) of peanut plants under Fe sufficiency(100 μmol L~(-1)ethylenediaminetetraacetic acid(EDTA)-Fe) and Fe deficiency(0 μmol L~(-1)EDTA-Fe). We also investigated the production of NO in peanut plants subjected to Fe deficiency with foliar application of sodium nitroprusside(SNP), a donor of NO, and/or EBR. The results showed that Fe deficiency resulted in severe chlorosis and oxidative stress, significantly decreased the concentration of chlorophylls and active Fe, and significantly increased NO production. Foliar application of NO and/or EBR increased the activity of antioxidant enzymes, superoxide dismutase,peroxidase, and catalase, and decreased the ROS and MDA concentrations, thus enhancing the resistance of plants to oxidative stress.Application of NO also significantly increased Fe translocation from the roots to the shoots and enhanced the transfer of Fe from the cell wall fraction to the cell organelle and soluble fractions. Consequently, the concentrations of available Fe and chlorophylls in the leaves were elevated. Furthermore, the activities of H~+-ATPase and FCR were enhanced in the Fe-deficient plants. Simultaneously,there was a significant increase in NO production, especially in the plants that received NO, regardless of Fe supply. These suggest that NO or EBR, and, especially, their combination are effective in alleviating plant chlorosis induced by Fe deficiency.     

水稻突变体对镉的吸收及其亚细胞分布和化学形态特点

Wild-type （Zhonghua 11） and mutant rice （Oryza sativa L.） plants were used to investigate the effect of cadmium （Cd） application on biomass production, to characterize the influx of Cd from roots to shoots, and to determine the form, content, and subcellular distribution of Cd in the roots, leaf sheaths, and leaves of the rice plants. Seedlings were cultivated in a nutrient solution and were treated with 0.5 mmol L^-1 of Cd^2＋ for 14 d. The sensitivity of rice plants to Cd toxicity was tested by studying the changes in biomass production and by observing the onset of toxicity symptoms in the plants. Both the wild-type and mutant rice plants developed symptoms of Cd stress. In addition, Cd application significantly （P ≤ 0.01） decreased dry matter production of roots, leaf sheaths, and leaves of both types, especially the mutant. The Cd content in roots of the mutant was significantly （P ≤0.05） higher than that of the wild-type rice. However, there was no significant difference in the Cd content of roots, leaf sheaths, and leaves between the wild-type and mutant rice. Most of the Cd was bound to the cell wall of the roots, leaf sheaths, and leaves, and the mutant had greater Cd content in cell organelles than the wild type. The uneven subcellular distribution could be responsible for the Cd sensitivity of the mutant rice. Furthermore, different chemical forms of Cd were found to occur in the roots, leaf sheaths, and leaves of both types of rice plants. Ethanol-, water-, and NaCl-extractable Cd had greater toxicity than the other forms of Cd and induced stunted growth and chlorosis in the plants. The high Cd content of the toxic forms of Cd in the cell organelles could seriously damage the cells and the metabolic processes in mutant rice plants.     

丛枝菌根真菌对万寿菊生长、吸镉及生理特性的影响

A pot experiment was carried out to study the effects of three arbuscular mycorrhizal fungi (AMF), including Glomus intraradices, Glomus constrictum and Glomus mosseae, on the growth, root colonization and Cd accumulation of marigold (Tagetes erecta L.) at Cd addition levels of 0, 5 and 50 mg kg-1 in soil. The physiological characteristics, such as chlorophyll content, soluble sugar content, soluble protein content and antioxidant enzyme activity, of Tagetes erecta L. were also investigated. The symbiotic relationship between the marigold plant and arbuscular mycorrhizal fungi was well established under Cd stress. The symbiotic relationship was reffected by the better physiobiochemical parameters of the marigold plants inoculated with the three AMF isolates where the colonization rates in the roots were between 34.3% and 88.8%. Compared with the non-inoculated marigold plants, the shoot and root biomass of the inoculated marigold plants increased by 15.2%- 47.5% and 47.8%-130.1%, respectively, and the Cd concentration and accumulation decreased. The chlorophyll and soluble sugar contents in the mycorrhizal marigold plants increased with Cd addition, indicating that AMF inoculation helped the marigold plants to grow by resisting Cd stress. The antioxidant enzymes reacted differently with the three AMF under Cd stress. For plants inoculated with G. constrictum and G. mosseae, the activities of superoxide dismutase (SOD) and catalase (CAT) increased with increasing Cd addition, but peroxidase (POD) activity decreased with increasing Cd addition. For plants inoculated with G. intraradices, three of the antioxidant enzyme activities were significantly decreased at high levels of Cd addition. Overall, the activities of the three antioxidant enzymes in the plants inoculated with AMF were higher than those of the plants without AMF inoculation under Cd stress. Our results support the view that antioxidant enzymes have a great influence on the biomass of plants, and AMF can improve the capability of reactive oxygen species (ROS) scavenging and reduce Cd concentration in plants to alleviate Tagetes erecta L. from Cd stress.     

钙离子通过调节抗氧化酶活性保护NaCl对菊芋的毒害

The ameliorative effect of external Ca^2＋ on Jerusalem artichoke （Helianthus tuberosus L.） under salt stress was studied through biochemical and physiological analyses of Jerusalem artichoke seedlings treated with or without 10 mol L^-1 CaCl2, 150 mmol L^-1 NaCl, and/or 5 mmol L^-1 ethylene-bis（oxyethylenenitrilo）-tetraacetic acid （EGTA） for five days. Exposure to NaC1 （150 mmol L^-1） decreased growth, leaf chlorophyll content, and photosynthetic rate of Jerusalem artichoke seedlings. NaC1 treatment showed 59% and 37% higher lipid peroxidation and electrolyte leakage, respectively, than the control. The activities of superoxide dismutase （SOD）, peroxidase （POD）, and catalase （CAT） were decreased by NaCl, indicating an impeded antioxidant defense mechanism of Jerusalem artichoke grown under salt stress. Addition of 10 mmol L^-1 CaCl2 to the salt solutions significantly decreased the damaging effect of NaC1 on growth and chlorophyll content and simultaneously restored the rate of photosynthesis almost to the level of the control. Ca^2＋ addition decreased the leaf malondialdehyde （MDA） content and electrolyte leakage from NaCl-treated seedlings by 47% and 24%, respectively, and significantly improved the activities of SOD, POD, and CAT in NaCl-treated plants. Addition of EGTA, a specific chelator of Ca2＋, decreased the growth, chlorophyll content, and photosynthesis, and increased level of MDA and electrolyte leakage from NaCl-treated plants and from the control plants. EGTA addition to the growth medium also repressed the activities of SOD, POD, and CAT in NaCl-treated and control seedlings. External Ca2＋ might protect Jerusalem artichoke against NaC1 stress by up-regulating the activities of antioxidant enzymes and thereby decreasing the oxidative stress.     

油菜光合生产模拟模型

Photosynthetic production is a major determinant of final yield in crop plants. A simulation model was developed for canopy photosynthesis and dry matter accumulation in oilseed rape (Brassica napus L.) based on the ecophysiological processes and using a three-layer radiation balance scheme for calculating the radiation interception and absorption by the layers of flowers, pods, and leaves within the canopy. Gaussian integration method was used to calculate photosynthesis of the pod and leaf layers, and the daily total canopy photosynthesis was determined by the sum of photosynthesis from the two layers of green organs. The effects of physiological age, temperature, nitrogen, and water deficit on maximum photosynthetic rate were quantified. Maintenance and growth respiration were estimated to determine net photosynthetic production. Partition index of the shoot in relation to physiological development time was used to calculate shoot dry matter from plant biomass and shoot biomass loss because of freezing was quantified by temperature effectiveness. Testing of the model for dynamic dry matter accumulation through field experiments of different genotypes, sowing dates, and nitrogen levels showed good fit between the observed and simulated data, with an average root mean square error of 10.9% for shoot dry matter. Thus, the present model appears to be reliable for the prediction of photosynthetic production in oilseed rape.     

水稻对水稻土中甲磺隆结合残留的响应

Metsulfuron-methyl is one of the widely used sulfonylurea herbicides. However, approximately half of the applied metsulfuron-methyl may remain as bound residues in soil. To characterize the response of rice plants to residual metsulfuron-methyl in soil, the activities of acetolactate synthase （ALS）, superoxide dismutase （SOD）, peroxidase （POD）, and catalase （CAT） were investigated in two rice varieties that differed in susceptibility to the herbicide. Changes in the activity of these enzymes in leaves and roots of Xiushui 63, a sensitive rice variety, were greater than those in a resistant variety Zhenong 952. Irrespective of variety, changes in the enzyme activity were greater in the roots than in the leaves. The activities of ALS and CAT decreased, while the SOD activity increased with the increase in the amounts of bound residues of metsulfuron-methyl （BRM） in soil. The POD activity increased at the BRM level of 0.025 mg kg^-1, but decreased at the BRM level of 0.05 mg kg^-1. The results showed that the bound residues of sulfonylurea herbicides may affect metabolism of rice plants.     

根区限制及氮营养对杂交小麦生长的影响

To study the physiological effects of small root zone, plants of a hybrid wheat variety (Triticum aestivum L. cv. Meiyou 4) were grown in small pots (1 litre) or large pots (8 litre) with low nitrogen (50 mg kg^-1 soil) and high nitrogen (200 mg kg^-1 soil). Restricting root zone decreased dry weight of plants at the stages of stem elongation and flowering, compared to those of control plants grown in the large pots (P<0.01). Spraying of 6-benzylaminopurine (50 μmol L^-1) increased dry weight of plants and chlorophyll concentration in leaves. Restriction of root zone decreased the concentrations of total nitrogen, chlorophyll and soluble protein in the flag leaf and accelerated senescence of the leaves. Supply of high nitrogen delayed senescence of the flag leaf. The results suggested that the shortage of nutrients, especially nitrogen deficiency, was the primary reason for the decreased growth of plant in the treatment of root zone restriction.     

深色有隔内生真菌柱孢顶囊壳对玉米幼苗生长、光合作用及耐铅能力的影响

Dark septate endophytic (DSE) fungi are ubiquitous and cosmopolitan,and occur widely in association with plants in heavy metal stress environment.However,little is known about the effect of inoculation with DSE fungi on the host plant under heavy metal stress.In this study,Gaeumannomyces cylindrosporus,which was isolated from Pb-Zn mine tailings in China and had been proven to have high Pb tolerance,was inoculated onto the roots of maize (Zea mays L.) seedlings to study the effect of DSE on plant growth,photosynthesis,and the translocation and accumulation of Pb in plant under stress of different Pb concentrations.The growth indicators (height,basal diameter,root length,and biomass) of maize were detected.Chlorophyll content,photosynthetic characteristics (net photosynthetic rate,transpiration rate,stomatal conductance,and intercellular CO2 concentration),and chlorophyll fluorescence parameters in leaves of the inoculated and non-inoculated maize were also determined.Inoculation with G.cylindrosporus significantly increased height,basal diameter,root length,and biomass of maize seedlings under Pb stress.Colonization of G.cylindrosporus improved the efficiency of photosynthesis and altered the translocation and accumulation of Pb in the plants.Although inoculation with G.cylindrosporus increased Pb accumulation in host plants in comparison to non-inoculated plants,the translocation factor of Pb in plant body was significantly decreased.The results indicated that Pb was accumulated mainly in the root system of maize and the phytotoxicity of Pb to the aerial part of the plant was alleviated.The improvement of efficiency of photosynthesis and the decrease of translocation factor of Pb,caused by DSE fungal colonization,were efficient strategies to improve Pb tolerance of host plants.     

Effects of Exogenous Nitric Oxide and 24-Epibrassinolide on the Physiological Characteristics of Peanut Seedlings Under Cadmium Stress

Cadmium(Cd) is highly toxic to plants, animals, and humans. Limited information is available on the role of nitric oxide(NO)and/or 24-epibrassinolide(EBR) in response of plants to Cd stress. In this study, a hydroponic experiment was performed to investigate the effects of NO and/or EBR on peanut plants subjected to Cd stress(200 μmol L~(-1)) with sodium nitroprusside(SNP, an exogenous NO donor)(250 μmol L~(-1)) and/or EBR(0.1 μmol L~(-1)) addition. The results showed that Cd exposure inhibited plant growth, and this stress was alleviated by exogenous NO or EBR, and especially the combination of the two. Treatment with Cd inhibited the growth of peanut seedlings, decreased chlorophyll content, and significantly increased the Cd concentration in plants. Furthermore, the concentration of reactive oxygen species(ROS) markedly increased in peanut seedlings under Cd stress, resulting in the accumulation of malondialdehyde(MDA) and proline in leaves and roots. Under Cd stress, applications of SNP, EBR, and especially the two in combination significantly reduced the translocation of Cd from roots to leaves, increased the chlorophyll content, decreased the concentrations of ROS, MDA, and proline, and significantly enhanced the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in peanut seedlings. Exogenous NO and/or EBR also stimulated the activities of nitrate reductase(NR)and nitric oxide synthase(NOS) and increased the contents of antioxidants, such as ascorbic acid(AsA) and reduced glutathione(GSH). Furthermore, exogenous NO and/or EBR enhanced Cd accumulation in the cell wall and thus decreased Cd distribution in the organelles in the roots. The concentrations of calcium(Ca), iron(Fe), magnesium(Mg), and zinc(Zn) were also regulated by exogenous NO or EBR, and especially by the two in combination. These results indicated that SNP and EBR, alone and particularly in combination, can mitigate the negative effects of Cd stress in peanut plants.     

发芽绿豆苗的生理指标和抗氧化特性对邻苯二甲酸酯的响应特征

Single phytotoxicity of two representative phthalate esters （PAEs）, di-n-butyl phthalate （DnBP） and bis（2-ethylhexyl） phthalate （DEHP）, was tested in mung bean （Vigna radiata） seedlings germinated for 72 h in soils spiked with varying concentrations （0-500 mg kg-1 soil） of DnBP or DEHP. PAEs added at up to 500 mg kg-1 soil exerted no significant effect on germination but both pollutants significantly inhibited root elongation （P 〈 0.01）; DEHP inhibited shoot elongation （P 〈 0.01） and DnBP depressed biomass on a fresh weight basis （P 〈 0.05）. Seedling shoot and root malondialdehyde （MDA） Contents tended to be stimulated by DnBP but inhibited by DEHP. However, increases in superoxide dismutase, peroxidase, ascorbate peroxidase and polyphenol oxidase activities, as well as glutathione （GSH） content, were induced at higher concentrations （e.g., 20 mg kg-1） of both compounds. Accumulation of proline in both roots and shoots and the storage compounds, such as free amino acids and total soluble sugars, in whole plant was induced under the stress exerted by both PAEs. The general responses of mung bean seedlings indicated higher toxicity of DnBP than DEHP on primary growth, during which root elongation was a more responsive index. MDA and GSH were more sensitive parameters in the roots than in the shoots and they might be recommended as physiologically sensitive parameters to assess the toxicity of PAE compounds in soils in future long-term studies.     

水稻和杂草稻对镉胁迫反应的比较研究

采用水培实验,研究不同浓度Cd2＋胁迫对水稻和杂草稻植株的生长、色素含量、抗氧化酶的活性、丙二醛含量、相对电导率以及脯氨酸含量的影响。结果表明：（1）Cd2＋胁迫条件下,水稻和杂草稻植株地上部分外观伤害随着Cd2＋浓度的升高而加重。（2）水稻和杂草稻的叶绿素a、叶绿素b和叶绿素总量含量均表现为Cd2＋胁迫浓度〈0.5 mg.L-1时升高,Cd2＋胁迫浓度〉0.5 mg.L-1时降低的现象;水稻和杂草稻的类胡萝卜素含量也都表现出Cd2＋胁迫浓度〈0.5 mg.L-1时降低,然后升高,最后在Cd2＋胁迫浓度〉1 mg.L-1时降低的现象。（3）水稻的SOD、POD、CAT活性表现出在Cd2＋浓度〈1 mg.L-1时升高,在Cd2＋浓度〉1 mg.L-1时降低的现象;杂草稻的SOD、CAT活性表现出在Cd2＋浓度〈2 mg.L-1时升高,在Cd2＋浓度〉2 mg.L-1时降低的现象,杂草稻的POD活性表现出随着Cd2＋浓度的升高而升高的现象;抗氧化酶活性随着Cd2＋浓度升高的变化幅度是水稻〉杂草稻。（4）Cd2＋胁迫使水稻和杂草稻的丙二醛含量、相对电导率以及脯氨酸含量显著增加,且增加幅度是水稻〉杂草稻,说明水稻产生了较严重的膜脂过氧化。总之,对于Cd2＋胁迫,在敏感性上水稻〉杂草稻,在抗性上杂草稻〉水稻。     

铅胁迫对紫穗槐光合作用及生理生化特征的影响

以紫穗槐幼苗为材料,通过盆栽试验,研究不同浓度(0、100、300、600 mg·kg~(-1))铅(Pb)胁迫条件下,紫穗槐叶片中的丙二醛(MDA)含量、抗氧化酶(SOD、POD、CAT)活性等生理指标和光合作用参数以及叶绿素荧光参数对Pb胁迫的响应。结果表明:紫穗槐叶片中MDA含量和电解质外渗率随着Pb胁迫程度的增加呈升高趋势,Pb胁迫提高了紫穗槐叶片中抗氧化酶SOD、POD的活性;100 mg·kg~(-1)Pb胁迫处理下,紫穗槐净光合速率(Pn)显著高于对照组;Pb胁迫浓度达到300 mg·kg~(-1)时,紫穗槐抗氧化酶活性、相对叶绿素含量(SPAD值)显著升高;600 mg·kg~(-1)Pb胁迫下CAT活性开始有所降低,光合作用降低主要受非气孔限制因素的影响,对紫穗槐叶绿素荧光特性未造成严重损伤。说明紫穗槐对环境中Pb(600 mg·kg~(-1))污染的耐受能力较强。     

镁对大豆叶片细胞膜透性和保护酶活性的影响

采用溶液培养方法研究不同的镁水平对两个大豆品种在五叶期和盛花期叶片细胞膜透性和保护酶活性的变化。结果表明,在缺镁胁迫下,大豆叶片的质膜透性(MP)和丙二醛(MDA)含量显著增加,产生的活性氧物质诱导超氧化物歧化酶(SOD)和过氧化物酶(POD)活性升高,而过氧化氢酶(CAT)活性下降;而施镁则能明显降低大豆叶片MP和MDA含量,提高CAT活性,有利于大豆抗膜脂过氧化胁迫。在施镁1～10.mg/L浓度下,大豆叶片的质膜透性和MDA以及SOD和POD活性均达最低值,而CAT活性则达最高值。说明在低镁胁迫下,大豆叶片的CAT活性受到抑制,而适量施镁则大大增强了CAT活性,有利于大豆体内活性氧的清除和抗逆境胁迫能力的提高。各处理下,大豆盛花期SOD和CAT活性明显降低,说明随着时间的延长,大豆叶片细胞内产生过多的活性氧超出了酶的防御能力,造成了酶活性伤害,而POD活性则变化不大;说明POD对活性氧具有较强的耐受性,是盛花期时起主要清除活性氧的作用的保护酶。本试验表明,大豆体内保护系统所存在的酶类在抵御逆境胁迫中相互协调,协同抗氧化。     

喷施不同化学制剂对水稻叶片抗高温胁迫的效果分析

以杂交早籼稻陵两优268为研究对象,采用盆栽实验,在水稻拔节期连续3d对叶片喷施4种不同浓度的抗高温化学制剂,分别为1.5mmol·L-1和2.5mmol·L-1的次硅酸钠（Na2SiO3·9H2O溶液）,0.5mmol·L-1和1.5mmol·L-1水杨酸（SA）溶液,10.0mmol·L-1和20.0mmol·L-1的氯化钙溶液（CaCl2·5H2O）溶液和22.04mmol·L-1和36.74mmol·L-1的磷酸二氢钾（KH2PO4）溶液,以叶面喷施蒸馏水为对照（CK）。利用人工气候箱进行5d高温处理（6：00-18：00,40±0.5℃;18：00-次日6：00,30±0.5℃,日平均气温为35℃）,在高温处理72h、120h和高温处理结束后自然条件下室外恢复120h,分别测定水稻叶片叶绿素含量、SOD、POD、CAT活性、MDA和可溶性蛋白质含量,研究不同化学制剂对水稻高温胁迫的缓解作用。结果表明：高温胁迫条件下,与CK相比,喷施4种化学制剂皆可显著提高水稻叶片叶绿素含量,提高SOD、POD、CAT活性和可溶性蛋白质含量,减少MDA含量;其中以喷施20.0mmol·L-1CaCl2·5H2O溶液和22.04mmol·L-1KH2PO4溶液作用效果最显著,喷施KH2PO4溶液在整个高温处理过程及高温结束后恢复120h、喷施CaCl2·5H2O溶液在高温处理120h和高温结束后恢复120h水稻叶片的抗衰老能力最强。     

Mn对超富集植物短毛蓼（Polygonum pubescens Blume）抗氧化机理的影响

采用水培的方法,研究了不同浓度Mn（0、0.5、1、2、4、8mmol·L-1）对新发现的Mn超富集植物短毛蓼（Polygonum pubescens Blume）生长、Mn吸收及Mn对其抗氧化酶和非酶系统的影响。结果表明,锰处理显著增加了（P〈0.05）短毛蓼根、茎、叶中Mn的含量,锰处理还引起了短毛蓼叶片中过氧化氢（H2O2）和丙二醛（MDA）的累积。当Mn处理浓度大于1mmol·L-1时,显著降低了短毛蓼的株高、株重（P〈0.05）;当Mn处理浓度为8mmol·L-1时,短毛蓼叶片中叶绿素a、叶绿素b、叶绿素a＋b含量最低,与对照差异显著（P〈0.05）。Mn处理显著提高了短毛蓼叶片中超氧物歧化酶（SOD）活性（P〈0.05）,而过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）的活性呈先升后降趋势,表明Mn处理打破了短毛蓼活性氧物质的正常代谢,并启动了抗氧化酶系统。8mmol·L-1的Mn处理,显著提高了短毛蓼叶片中巯基（-SH）、还原型谷胱甘肽（GSH）的含量（P〈0.05）,比对照分别提高了10.6%和20%,表明-SH、GSH在短毛蓼缓解Mn毒害的过程中起着重要作用。     

硅对水稻叶片抗氧化酶活性的影响及其与白叶枯病抗性的关系

以感白叶枯病的水稻品种日本晴(Oryza sativa L. cv. Nipponbare)为材料,在溶液培养条件下,研究了硅对接种白叶枯病菌后的水稻病情指数、叶片丙二醛(MDA)和过氧化氢(H2O2)含量以及超氧化物岐化酶(SOD)、过氧化氢酶(CAT)、脂氧合酶(LOX)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性的影响。结果表明,施硅能显著降低水稻白叶枯病的病情指数,防治效果达62.86%。接种白叶枯病菌后48 h内,施硅处理的水稻植株,叶片中丙二醛(MDA)和过氧化氢(H2O2)含量显著升高;显著提高感病植株叶片中脂氧合酶(LOX)和超氧化物歧化酶(SOD)活性;降低过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性;促进过氧化氢(H2O2)在植物体内积累,加强膜脂过氧化作用。因此,硅可通过参与植株体内代谢,调节抗氧化系统酶活性,激发机体过敏反应(HR),增强植株对白叶枯病抗性。     

不同浓度镉胁迫对玉米幼苗光合作用、脂质过氧化和抗氧化酶活性的影响

以玉米为材料,通过营养液培养试验,研究浓度为5~100 μmol/L的镉胁迫后不同时间内,植株体内活性氧代谢及其抗氧化酶活性的变化特征,探讨镉胁迫导致植物体内活性氧自由基累积的原因及不同程度镉胁迫对植物体内活性氧代谢的影响。随着加镉量的增加,玉米地上部生物量明显降低,而根部生物量未表现出差异。镉处理降低了叶片光合作用速率,高镉处理的影响较早。镉处理4d后,5、20、和100 mol/L Cd2+浓度处理玉米叶片Fv/Fm减小,PSII系统的原初光能转换效率下降,但比光合作用速率下降的时间要晚;镉处理7d的叶片中丙二醛（MDA）含量还没有受到明显影响,但20和100 μmol/L Cd2+处理4d后,根系膜质过氧化增强,MDA含量升高。随着镉浓度升高,处理时间延长,活性氧酶清除系统包括超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）等酶活性明显增加,受到镉胁迫诱导,高浓度镉处理该现象出现更早。本文试验结果表明,镉胁迫下植物体内活性氧形成增多,诱导活性氧酶清除系统活性升高,其中一个重要原因是与CO2同化受到限制有关。     

缺镁对菜豆幼苗膜脂过氧化及体内活性氧清除酶系统的影响

营养液中培养菜豆幼苗,缺镁菜豆植株生长受抑,生物量显著低于正常供应镁的植株,体内镁浓度和镁的积累总量均较低。严重缺镁黄化叶片中叶绿素含量下降。完整叶绿体的希尔反应值在缺镁与正常植株间无差别。缺镁菜豆植株的根和叶膜造性（以相对电导率表示）增加,叶片中丙二醛含量升高。活性氧清除酶系统:SOD、POD、CAT活性在缺镁菜豆真叶中高于正常植株,老叶中抗坏血醒过氧化物酶（AsA-POD）活性增加程度也较大。     

锌铬复合污染对水稻根系抗氧化酶活性的影响

为了研究水稻在金属复合污染条件下的适应过程,该文就成都平原两种常见的重金属污染元素(锌、铬)对土壤复合处理后,进行水稻盆栽试验.结果表明,锌铬复合污染条件下,在水稻不同生育期,水稻根系3种抗氧化酶(SOD,POD和CAT)活性随锌、铬浓度的增加而表现出不同的变化趋势.在水稻分蘖期,随铬浓度的增加,水稻根系SOD活性和POD活性呈先降后升的变化趋势;随锌浓度的增加,水稻根系SOD活性和POD活性呈升高的趋势;而水稻根系CAT活性则随锌、铬浓度的增加呈一定的降低趋势.在水稻孕穗期,随锌、铬浓度的增加,水稻根系SOD活性呈先降后升的变化趋势,POD活性及CAT活性则呈降低的趋势.在水稻灌浆结实期,水稻根系SOD、POD及CAT活性均呈一定的降低趋势.水稻籽粒产量随锌、铬浓度的增加呈降低的趋势.锌、铬浓度对水稻籽粒产量产生了复合效应,并与水稻籽粒产量有极显著的线性回归关系.这表明水稻通过调节自身的生理代谢能提高对锌铬复合污染的生态适应性,这能为培育适合重金属污染地区生长的水稻品种提供理论基础.