NaCl盐胁迫对锦鸡儿保护酶系的影响

[目的]探索锦鸡儿在盐胁迫下的生化指标。[方法]对锦鸡儿幼苗进行不同浓度的NaCl处理,测定并比较了幼苗体内SOD、CAT和POD活性的变化。[结果]在NaCl胁迫下,锦鸡儿幼苗体内SOD、POD和CAT活性随NaCl浓度的增高均呈先上升后下降的趋势,并可清除幼苗体内的部分活性氧,对幼苗起一定的保护作用。这3种酶活性在NaCl浓度为300mmol／L时均出现峰值,超过这个临界浓度后均显著下降。锦鸡儿幼苗体内活性氧的保护酶体系主要途径是SOD—POD＋CAT。SOD一直保持较高水平,可清除超氧自由基使幼苗初期免受伤害,同时,SOD催化超氧自由基的产物由POD和CAT共同协作来清除,表明3种酶的协同作用增强了植物对逆境的忍耐力。[结论]300mmol／L的NaCl浓度是适宜锦鸡儿生长的临界土壤盐浓度。     

磷胁迫对油菜幼苗Apase·POD ·CAT活性的影响

以耐低磷油菜品种中油821为材料,研究足磷和缺磷条件下幼苗的形态和生理生化特性。对甘蓝型油菜821足磷和缺磷处理后的形态比较观察发现,缺磷处理后,形态学与对照有明显变化。地上部分真叶生长缓慢,植株矮小,叶片较小,叶柄较粗;地下部分主根细、纤弱。对油菜幼苗根部的酸性磷酸酶活性检测发现,缺磷处理后,酶的活性显著增加,且随着胁迫时间的延长,酶的活性随之增大。酸性磷酸酶活性的变化表现出油菜根部对低磷胁迫的适应性反应。对磷胁迫下油菜幼苗叶片的过氧化物酶和过氧化氢酶活性测定发现,在磷胁迫的初期2个酶的活性均显著增加,且随着处理时间的延长,过氧化物酶的活力逐渐降低,而过氧化氢酶的活力则变化不明显。     

Impact of sodium cyanide on catalase activity in the freshwater exotic carp, Cyprinus carpio (Linnaeus)

The Cyprinus carpio fingerlings on exposure to lethal (1 mg/L) and sub lethal concentrations (0.066 mg/L) of sodium cyanide showed inhibition in the activity of catalase. The disruption of catalase activity in freshwater fish, C. carpio is demonstrated in the present study using UV–visible spectrophotometer at 240 nm using hydrogen peroxide as a substrate. It suggests toxic effects of sodium cyanide and consequent accumulation of hydrogen peroxide in the functionally different tissues namely, liver, gill, muscle and brain. This might lead to cellular damages, and create widespread physiological disturbance. The results suggest that catalase activity can be a good diagnostic tool for sodium cyanide toxicity in biomonitoring programme.     

沙棘叶片内过氧化氢酶的研究

[目的]研究沙棘叶片内过氧化氢酶（CAT）的酶活力和酶催化特性,为沙棘的开发利用提供参考。[方法]采用紫外分光光度法,对沙棘叶片内CAT活性进行测定,并研究温度、pH值、激活剂和抑制剂对其活性的影响。[结果]沙棘叶片CAT的最适温度在20～30℃之间,最适pH值为7.0。Mg2＋、Cu2＋和SDS对沙棘CAT有激活作用,而EDTA、Fe2＋、Ca2＋、Ag＋、Mn2＋和Fe3＋则有较强的抑制作用。在pH值为7.0,温度为30℃时,CAT活性可达1733U/g.min;[结论]沙棘叶片内过氧化氢酶具有很强的活性,温度、pH值、激活剂和抑制剂对其有明显影响。     

豇豆CAT活性的研究

[目的]对豇豆过氧化氢酶（CAT）的活性进行研究。[方法]以豇豆中的过氧化氢酶为材料,测定其活力、最适温度与pH值,及各因素对活力的影响。[结果]豇豆中过氧化氢酶的最适pH值为8.0,最适温度为25℃。甲醇和乙醇对豇豆中过氧化氢酶活性的影响均表现为低浓度具有激活作用,高浓度转为抑制作用。金属离子Cu2＋对该酶有不用程度的激活作用,而Mg2＋和Na＋则对该酶有一定程度的抑制作用。[结论]该研究为豇豆过氧化氢酶的进一步研究提供了理论依据。     

栽培稻杂交后代保护酶活性的变化

以抗水稻细菌性条斑病（简称细条病）的普通野生稻DY3和感病轮回亲本9311组合构建了BC2F2群体．分蘖期用针刺法人工接种广西细菌性条斑病菌优势致病型菌株JZ28,选取其中的1、3、5、7、9级植株为材料,在孕穗期接种第2次,研究接种细条病后水稻叶片防御酶活性的变化动态及其与抗病性的关系。结果表明：高抗病1级与高感病9级材料的苯丙氨酸解氨酶（PAL）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）的活性和丙二醛（MDA）含量与对照亲本时间动态变化趋势相似,而过氧化物酶（POD）活性变化不一致;不同抗病等级之间,苯丙氨酸解氨酶活性和过氧化氢酶活性在极端抗感材料之间差异显著．超氧化物歧化酶、过氧化物酶活性和丙二醛含量差异不显著．     

过氧化氢酶和抗坏血酸过氧化物酶对镉胁迫下水稻根系生长的影响

[目的]研究过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）与镉胁迫水稻根系生长发育的关系。[方法]以水稻中花11号为材料,研究Cd、Cd＋CAT抑制剂和Cd＋APX抑制剂处理条件下水稻幼苗的变化。[结果]在Cd胁迫下,抑制CAT活性,导致地上部分的生长受到显著抑制,引起不定根和侧根数量的减少,但显著促进了不定根和侧根的伸长生长;同时,初生根和不定根上第一侧根距根尖的距离也比对照的增加。抑制APX活性,水稻的生长变化与CAT抑制剂处理的类似。[结论]在正常和胁迫条件下CAT和APX对水稻的生长可能具有重要的调节作用。     

Catalase peroxidase and IAA‐oxidase activities and O‐diphenolics contents in sunflower leaves grown with different boron levels

Cataiase, peroxidase and IAA‐oxidase activities, so as odiphenolics content in sunflower leaves grown in hydroponics with 4 B levels (0.05; 0.25; 0.5 and 2.0 ppm) were determined. The biochemical assays were made when visual symptons were clearly developed.

Cataiase activity significantly increased in B deficient leaves. Peroxidase, IAA‐oxidase activities and o‐diphenolics content did not significantly change with B levels. The lag period for IAA‐oxidase activity was significantly reduced in B deficient and toxic leaves with respect to the normal ones. These results are in accordance with the hypothesis that one of the B action could be to enhance cataiase activity, the “in vivo” decrease of H₂O₂ levels beeing the cause of the variation in other enzymatic activities related with that substrate.     

Activities of Iron‐Containing Enzymes in Leaves of Two Tomato Genotypes Differing in Their Resistance to Fe Chlorosis

Abstract

Two tomato (Lycopersicon esculentum Mill., cvs. Pakmor and Target) genotypes differing in resistance to iron (Fe) deficiency were grown in nutrient solution under controlled environmental conditions over 50 days to study the relationships between severity of leaf chlorosis, total concentration of Fe, and activities of Fe‐containing enzymes in leaves. The activities of Fe‐containing enzymes ascorbate peroxidase, catalase, and guaiacol peroxidase, and additionaly the activity of glutathione reductase, an enzyme that does not contain Fe, were measured. Plants were supplied with 2 × 10^?7 M (Fe deficient) and 10^?4 M (Fe sufficient) FeEDTA, respectively. Leaf chlorosis appeared more rapidly and severely in Target (Fe deficiency senstive genotype) than Pakmor (Fe deficiency resistant genotype). On day 50, Pakmor had 2‐fold more chlorophyll than Target under Fe deficiency, while at adequate supply of Fe the two genotypes were very similar in chlorophyll concentration. Despite distinct differences in development of leaf chlorosis and chlorophyll concentrations, Pakmor and Target were very similar in concentrations of total Fe under Fe deficiency. In contrast to Fe concentration, activities of Fe‐containing enzymes were closely related to the severity of leaf chlorosis. The Fe‐containing enzymes studied, especially catalase, showed a close relationship with the concentration of chlorophyll and thus differential sensitivity of tomato genotypes to Fe deficiency. Glutathione reductase did not show relationship between Fe deficiency chlorosis and enzyme activity. The results confirm that measurement of Fe‐containing enzymes in leaves is more reliable than the total concentration of Fe for characterization of Fe nutritional status of plants and for assessing genotypical differences in resistance to Fe deficiency. It appears that Fe deficiency‐resistant genotype contains more physiologically available Fe in tissues than the genotype with high sensitivity to Fe deficiency.     

Effect of Iron Deficiency on Gas Exchange and Catalase and Peroxidase Activity in Citrus

Abstract

The effects of iron (Fe) deficiency on catalase and peroxidase activity, net photosynthesis (Pn), stomatal conductance (g _s ), plant water relations, and specific leaf weight, were studied under greenhouse conditions in two sweet orange (C. sinensis) cultivars grafted on sour orange (Citrus aurantium) and Swingle citrumelo (C. paradisi × P. trifoliata). Iron deficiency caused by the absence of Fe in the Hoagland nutrient solution reduced significantly catalase and peroxidase activity, photosynthesis (Pn), osmotic potential (Ψ _π ), turgor potential (Ψ _p ), and specific leaf weight, but did not influence g _s and leaf water potential (Ψ _L ). Iron deficiency caused by increasing concentrations of bicarbonate supplied as NaHCO₃ (10 and 40 mM) in the nutrient solution reduced significantly g _s , Pn, and Ψ _p and increased Ψ _L and Ψ _π . Furthermore, remarkable differences were recorded between the various cultivars/rootstocks combinations.