Effects of drought stress and selenium supply on growth and physiological characteristics of wheat seedlings

The paper studied the effects of drought stress, selenium (Se) supply and their combination on growth and physiological characteristics of wheat (Triticum aestivum L. cv Shijiazhuang NO. 8) seedlings. The experimental design included two water treatments (well-watered, 75% of maximum field capacity; drought stress, 30% of maximum field capacity) and two Se levels (0; 0.5 mg/kg) to determine whether Se can modify the negative impacts of drought stress on seedling growth and physiological traits. Drought stress caused a marked decline in growth parameters and soluble protein content, whereas it induced an increase in root activity, proline content and the activities of peroxidase (POD) and catalase (CAT) of leaf tissue. On the other hand, Se supply induced an increase in biomass accumulation only under well-watered condition. Under drought stress, Se supply increased free proline content, root activity and the activities of POD and CAT in leaf tissue, but did not significantly affect on growth parameters. These results implied that drought stress brought harmful effects on wheat seedlings, and that Se supply was favorable for biomass accumulation of wheat seedlings under well-watered condition. However, it did not significantly affect on biomass accumulation under drought stress, although it increased root activity and activities of some antioxidant index in experimental periods.     

铬、硒对水稻幼苗生长和生理的影响

以单一铬(Cr6+0～200μmol·L1)及硒(Se0～200μmol·L1)、铬硒混合液(铬100μmol·L1,硒50μmol·L1)处理水稻幼苗,研究不同处理和浓度对水稻幼苗生长和生理特性影响。结果表明(1)单一铬处理,随着铬浓度增加,植株生长明显受到抑制,铬毒害表现为株高、鲜重和干重受抑制,叶片黄色、叶绿素含量下降,体内SOD、CAT活性下降,POD活性上升,膜透性增大;(2)单一硒处理,50μmol·L1促进植株生长,100μmol·L1和200μmol·L1则抑制植株生长;(3)铬硒混合处理结果反映,硒有减轻水稻铬毒害的作用,表现为:减轻铬胁迫对株高、鲜重和干重增加的抑制,提高叶绿素含量,提高SOD、CAT活性,降低POD活性和膜透性。     

Effects of Selenium on Wheat Seedlings Under Drought Stress

The paper reports the effects of selenium (Se) supply on growth and some physiological traits of wheat (Triticum aestivum L. cv Shijiazhuang NO. 8) seedlings exposed to drought stress. The growth and physiological responses of seedlings were different depending on the Se concentration. The higher (3.0 mg Se kg⁻¹) and lower amount used (0.5 mg Se kg⁻¹) did not significantly affect on biomass accumulation. Treatments with 1.0 and 2.0 mg Se kg⁻¹ promoted biomass accumulation of wheat seedlings. Treatments at 1.0, 2.0, and 3.0 mg Se kg⁻¹ significantly increased root activity, proline content, peroxidase (POD), and catalase (CAT) activities, carotenoids (Car) content, chlorophyll content, and reduced malondialdehyde (MDA) content of wheat seedlings. Lower Se treatment did not significantly effect on chlorophyll content and MDA content, although it also increased some antioxidant index (proline and Car content, POD and CAT activities) in wheat seedlings. These results suggest that optimal Se supply is favorable for growth of wheat seedlings during drought condition.     

Differences in the activity and distribution of peroxidases from three different portions of germinating Brassica oleracea seeds

Peroxidase (POD, EC 1.11.1.7) activity, cellular localization and isozyme patterns were investigated in the seed integument, cotyledon and embryo axis of Brassica oleracea cv. Cappuccio during pregermination and seedling growth. Seeds started to germinate after 24 h of imbibition. POD activity was localized in the pigmented layer of the integument and in procambial strands of the cotyledon and embryo axis in the first 24 h of imbibition. It was localized in the integumental cells of palisade, pigmented and aleurone layers and in epidermal, meristematic, procambial cells and xylem elements of the root and hypocotyl after 48 h of imbibition. POD activity increased during germination and early seedling growth: in the integument, it reached a maximum value after 72 h of imbibition, in the embryo axis and cotyledons, it increased up to 144 h of imbibition. The increase in peroxidase activity was accompanied by the appearance of new isozymes correlated with the development of seedling tissues. The isozyme profile was characterized by nine peroxidases: isoperoxidase of 50 kDa peculiar to integuments, that of 150 kDa to cotyledons and that of 82 kDa to the embryo axis. During pregerminative phase isozymes of 84 kDa were detected in the integument and cotyledons, of 48.5 kDa in the embryo axis. After germination, peroxidase activity and the complexity of the isozyme pattern increased, suggesting that they play a relevant role after rupture of the integument.     

硒对三裂叶野葛毛状根生长及抗氧化酶活性的影响

本文研究硒(Se)对三裂叶野葛毛状根生长及抗氧化酶活性的影响。结果表明,低浓度亚硒酸钠(0~0.5 mg/L)可促进毛状根生长及异黄酮的生物合成,而高浓度亚硒酸钠抑制其生长和异黄酮的积累,且浓度愈高抑制作用愈强。此外,硒可促进可溶性蛋白的生物合成,亚硒酸钠浓度愈高促进作用愈明显;硒还可降低毛状根中SOD活性,提高POD活性,降低MDA含量。说明硒对三裂叶野葛毛状根生长和抗氧化酶活性有重要的调节作用。     

硒对镉胁迫下水稻幼苗生长及生理特性的影响

采用溶液培养 ,研究不同浓度的硒和镉处理对稻苗的株高、叶片干重、叶绿素、还原糖、叶片丙二醛含量以及保护酶 SOD、POD、CAT活性的影响。结果表明 ,镉胁迫下稻苗矮化 ,镉毒害使叶片失绿 ,干重降低 ,还原糖含量下降 ,叶片 MDA含量增加 ,POD活性增强 ,而 SOD、CAT活性降低 ;硒可减轻镉对水稻的毒害 ,表现为 :减轻镉胁迫对株高增加的抑制 ,提高叶绿素含量 ,增加叶片干物质积累 ,提高叶片还原糖含量 (Cd0 .5 mg/ L加 Se 0 .1 0～ 0 .5 0 mg/ L例外 ) ,降低 MDA含量与 POD活性 ,提高 SOD、CAT活性     

亚硫酸盐对小麦幼苗叶组织生长代谢的影响

在低浓度亚硫酸盐作用下,小麦幼苗叶片中超氧化物歧化酶（SOD）和过氧化物酶（POD）活性升高;随着亚硫酸盐浓度的增加,叶片的叶绿素含量下降,游离脯氨酸和脂质过氧化产物丙二醛（MDA）含量增加,SOD活性下降,POD活性显著升高。研究表明,高浓度的亚硫酸盐对植物生长有抑制和毒害作用。     

硒对水稻的生态毒理效应及临界指标研究

通过土壤添加硒盆栽试验,研究了黄棕壤不同浓度Se对水稻生物量、叶绿素含量、抗氧化酶系统的影响.结果表明,低浓度Se(<8mg·kg^-1)对水稻根和地上生物量、叶绿素a含量、叶绿素a/b有促进作用,并整体提高了作物抗氧化酶系统,使MDA下降,SOD、CAT、POD、GSHPx活性相应提高.而高浓度Se(>16mg·kg^-1)对水稻根和地上生物量、叶绿素a含量、叶绿素a/b有明显的抑制作用,对抗氧化酶系统产生胁迫效应,使GSHPx明显上升,MDA上升,SOD、CAT、POD酶活性明显下降.各项生理指标与土壤Se处理浓度之间相关分析表明,土壤Se浓度与地上部干重相对百分率、根干重百分率、叶绿素a/b、MDA、SOD、CAT、POD之间有显著相关性.比较胁迫效应10%值的临界指标EC10值表明,作物地上部干重抑制率作为土壤临界值制定的依据更为可靠,EC10为21mg·kg^-1.     

Separate and combined effects of silicon and selenium on salt tolerance of wheat plants

Soil salinity is the leading global abiotic stress which limits agricultural production with an annual increment of 10%. Therefore; a pot experiment was conducted with the aim to alleviate the salinity effects on wheat seedlings through exogenous application of silicon (Si) and selenium (Se). Treatments included in the study were viz. (Ck) control (no NaCl nor Si and Se added), only salinity (50 mM NaCl), salinity + Si (50 mM NaCl with 40 mM Si), salinity + Se (50 mM NaCl with 40 mM Se) and salinity + Si + Se (50 mM NaCl + 40 mM Si + 40 mM Si). The salt stress impaired the growth (root and shoot dry weight, root: shoot ratio, seedlings biomass), water relations, photosynthetic attributes, transpiration rate and chlorophyll contents of wheat seedlings. Nonetheless, the foliar application of Si and Se alone and in combination improved the growth, water relations, photosynthetic attributes, transpiration rate and chlorophyll contents of wheat seedlings under stressed conditions. Moreover, an increase in antioxidant enzyme activity and accumulation of osmo-protectants (proline, soluble protein and soluble sugar) was noted under stressed conditions, which was more pronounced in wheat seedling which experienced combined application of Si and Se. To conclude that, foliar application of Si alone mitigated the adverse effect of salinity, while the combined application of Si and Se was proved to be even more effective in alleviating the toxic effects of salinity stress on wheat seedlings.     

不同浓度硒酸钠对茶树的生长和生理指标的影响

该文以一年生扦插苗为材料,采用水培试验,研究不同浓度的硒酸钠(0、0.15、0.3、1.5、3、5、8 mg·L^-1)对茶苗的硒积累、植株生长、生理指标和根尖显微结构等参数的影响。结果表明:茶苗的根和新梢中的硒含量与营养液中的硒浓度正相关;随着硒浓度升高,茶苗的鲜重、侧根数量、根系生物量、光合色素含量、根系活力等生长指标,茶多酚、可溶性蛋白、可溶性糖等茶叶质量指标均呈现先升后降趋势;而丙二醛、过氧化氢、脯氨酸含量等抗逆生理指标则呈现先降后升趋势。显微结构分析显示在不同硒浓度处理条件下根尖的显微构造存在差异。低硒浓度(0.15、0.3、1.5 mg·L^-1)处理的茶苗根尖的皮层薄壁细胞饱满、完好,表皮细胞较小;高硒浓度(Se≥3 mg·L^-1)处理的茶苗根尖的皮层薄壁细胞变形或受损,表皮细胞增厚,表现出胁迫反应。上述结果说明硒对茶树具有双重效应,合适浓度(0.3 mg·L^-1)硒对茶树生长和茶叶品质有益,表现为光合作用和根系活力增强,过氧化物和脯氨酸含量降低,生物量增加,茶叶茶多酚含量增加;硒浓度过高(≥3 mg·L^-1)对茶苗的生长和茶叶品质有害,表现为茶苗出现胁迫反应,茶多酚降低。该研究结果为进一步研究硒对茶树的双重作用机制和富硒茶的栽培提供参考。     

Antioxidant Responses of Wheat Seedlings to Exogenous Selenium Supply Under Enhanced Ultraviolet-B

The paper reports the effects of selenium (Se) supply on growth and antioxidant traits of wheat (Triticum aestivum L. cv Han NO.7086) seedlings exposed to enhanced ultraviolet-B (UV-B) stress. Antioxidant responses of seedlings were different depending on the Se concentration. Compared with the control, the lower amount used (0.5 mg Se kg⁻¹ soil) had no significant effect on biomass accumulation. The treatments with 1.0, 2.0, and 3.0 mg Se kg⁻¹ promoted biomass accumulation of wheat seedlings, and the increased amount in biomass was the most at 1.0 mg Se kg⁻¹ treatment. Se treatments with 1.0, 2.0, and 3.0 mg kg⁻¹ also significantly increased activities of peroxidase (POD) and superoxide dismutase (SOD) and reduced the rate of superoxide radical (O₂⁻) production and malondialdehyde (MDA) content of wheat seedlings. In addition, anthocyanins and phenolic compounds content in wheat seedlings evidently increased by the treatments with 1.0 and 2.0 mg Se kg⁻¹. The lower Se treatment had no significant effect on MDA content, although it increased activities of antioxidant enzymes (POD, SOD, and catalase activities) and reduced the rate of O₂⁻ production in wheat seedlings. These results suggest that optimal Se supply is favorable for the growth of wheat seedlings and that optimal Se supply can reduce oxidative stress of seedlings under enhanced UV-B radiation.     

导入外源DNA对小麦基因表达的影响

用（ＳＤＳ）ＰＡＧＥ对外源豌豆ＤＮＡ导入小麦体的不良变异后代种子蛋白质和酯酶同工酶（ＥＳＴ）、超氧化物歧化酶（ＳＯＤ）、过氧化同工酶（ＰＯＤ）进行分析,发现变异小麦的种子蛋白质消减４个组分带,ＥＳＴ和ＰＯＤ消减２条酶谱带,ＳＯＤ的活性明显降低,并且变异小麦植株的发育生长表型呈现出脆弱,早衰迹象,表明导入外源ＤＮＡ抑制了某些基因的表达,同时分析导致这种负作用的原因。     

Study on the dose-effect relationship of selenite with the growth of wheat

The wheat in hydroponics culture has been chosen as a model to study the dose-effect relationship of selenite with its growth. Five different morphological end points and 12 different biological and biochemical end points during different phases of growth of wheat seedling and seed germination have been measured and analyzed. A dose-effect relationship of selenite with the growth of wheat has been obtained from data analysis. The results shows that critical threshold for beneficial effect is about 1.0 mg Se/L, and the critical threshold for adverse effect is about 5.0 mg Se/L in hydroponics culture. From the result of product of lipid peroxidation, it is assumed that the role of selenium for plant is related to the oxy-radical reaction.     

Comparative Effect of Selenium in Wheat,Barley, Fish Meal and Sodium Selenite for Prevention of Exudative Diathesis in Chicks

Groups af White Leghorn chicks obtained from dams deprived on selenium (Se), were fed from hatching a low-Se-vitamin E basal diet alone, or supplemented with 0.02, 0.04, 0.06 or 0.08 mg Se/kg diet, as sodium selenite (Na2SeO3 · 5H2O), wheat, barley or fish meal. Prevention of the Se-vitamin E deficiency responsive disease exudative diathesis (ED) as it was clinical observed, induction of the plasma Se dependent enzyme glutathione peroxidase (GSH-Px) activity, and Se concentration in the cardiac muscle were observed to be dietary Se level and source dependent. Slope ratio assay was applied to estimate the biological availability of Se in the natural sources relative to Se in sodium selenite. For the prevention of ED, the bioavailability of Se in wheat, barley and fish meal was 99, 85 and 80 %, respectively. The increase in the plasma GSH-Px activity revealed a bioavailability for Se in wheat, barley and fish meal of 79, 71 and 66 %, respectively. Using retention of Se in the cardiac muscle as the bioassay, a bioavailability of 108, 87 and 100 % was calculated for wheat, barley and fish meal Se, respectively.     

咖啡因对小麦幼苗生长、过氧化物酶同工酶及根尖细胞有丝分裂的影响

30ppm以上浓度的咖啡因对小麦种子萌发,幼苗生长和胚根长度均有明显抑制作用。随着咖啡因浓度的增加,根尖细胞有丝分裂指数明显下降。低浓度时,过氧化物酶同工酶和苹果酸脱氢酶没有变化,但高浓度时,使得这两种酶的活性几乎消失。     

咖啡因对小麦幼苗生长,过氧化物酶同工 酶及根尖细胞有丝分裂的影响

３０ｐｐｍ以下浓度的咖啡因对小麦种子萌发,幼苗生长和胚根长度均有明显抑制作用。随着咖啡因浓度的增加,根尖细胞有丝分裂指数明显下降。低浓度时,过氧化物酶同工酶和苹果,酸脱氢酶没有变化,但高浓度时,使得这两种酶的活性几乎消失。     

滇重楼种子水浸液对三种植物种子萌发和幼苗生长的影响

利用滇重楼(Paris polyphylla Smith var.yunnanensis(Franch.)Hand.-Mazz.)种子外种皮和胚乳的水浸液对白菜(Brassica pekinensis(Lour.)Rupr.)、绿豆(Vigna radiata(Linn.)Wilczak)、小麦(Triticum aestivum L.)种子进行处理,研究滇重楼种子水浸液对3种植物种子萌发、幼苗生长和保护酶活性的影响,并利用GC-MS方法对滇重楼种子内源抑制物的成分进行分析。结果显示,不同浓度滇重楼外种皮、胚乳水浸液对上述3种受体植物的发芽率、苗高、根长及鲜重均产生影响,其作用强度和水浸液的浓度有关,总体上表现出低促高抑的双重浓度效应。滇重楼种子水浸液对白菜的影响作用最强,对绿豆的影响作用最弱,且胚乳水浸液的影响较外种皮强。不同浓度滇重楼种子外种皮和胚乳水浸液均能影响3种植物幼苗体内保护酶的活性,随着水浸液浓度的升高,叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)活性总体增加,与对照相比差异显著。白菜、小麦过氧化氢酶(CAT)活性减少,与对照相比差异显著;绿豆过氧化氢酶(CAT)活性增加,但与对照相比无显著差异。利用GC-MS方法从胚乳和外种皮水浸液中分别检出8种和2种物质。研究结果表明滇重楼种子中存在内源抑制物质,可能是导致种子休眠的原因;种子水浸液可能通过影响植物幼苗保护酶的活性进而影响其正常生长;有机酸类物质可能是滇重楼种子内源抑制物之一。     

Influence of selenium deficiency on vital functions in rats

To clarify the relationship between selenium (Se) deficiency and functional disorders, the authors determined the Se concentration, anti-oxidant enzyme activity, and other parameters in rats fed a Se-deficient diet. Rats fed the Se-deficient diet showed a decrease in Se concentration and glutathione peroxidase (GSH-Px) activity in plasma, erythrocytes, heart, liver, and skeletal muscle from the first week after the initiation of the diet, an increase in heart lipid peroxide concentration from the second week, and an increase in liver glutathione S-transferase activity from the fourth week. From the twelfth week, a decrease in the growth rate in the rats fed the Se-deficient diet was observed. In spite of this growth impairment, no changes in electrocardiogram, muscle tone, degree of hemolysis, plasma biochemistry, or hematological values were detected. In summary, the authors found that a reduction of body Se is easily induced, but that the appearance of functional disorders following Se deficiency is difficult to detect in rats.     

Selenium improves the antioxidant ability against aluminium-induced oxidative stress in ryegrass roots

We investigated the role of selenium (Se) against aluminium (Al) stress in ryegrass by evaluating the growth responses and the antioxidant properties of plants cultured hydroponically with Al (0 or 0.2 mM) and selenite (0–10 µM Se). Al addition significantly reduced the yield and length of shoots and roots, and most Al was accumulated in the roots. Al also enhanced lipid peroxidation and activated the peroxidase (POD), ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes in the roots. Se application up to 2 µM improved root growth and steadily decreased thiobarbituric acid reactive substances (TBARS) accumulation in plants treated with 0 and 0.2 mM Al. However, above 2 µM, Se induced stress in plants grown with or without Al. Significant changes in antioxidant enzymes activities were also found as a result of the added Se. At low Se addition levels POD was activated, whereas APX activity decreased irrespective of added Al. Furthermore, Se supplied up to 2 µM greatly decreased root SOD activity in Al-stressed plants. Our study provides evidence that Se alleviated the Al-induced oxidative stress in ryegrass roots through the enhancement of the spontaneous dismutation of superoxide radicals and the subsequent activation of POD enzyme.     

Effects of selenium content in green parts of plants on the amount of ATP and ascorbate-glutathione cycle enzyme activity at various growth stages of wheat and oilseed rape

The aim of this experiment, conducted under greenhouse conditions, was to assess the influence of various H(2)SeO(3) concentrations added to soil (0.05, 0.15, and 0.45mMkg(-1)) on selenium and adenosine triphosphate (ATP) content, and on the activity of the ascorbate-glutathione cycle enzymes in green parts of wheat and oilseed rape. Selenium uptake by the test plants was found to vary, with content increasing from one developmental stage to the next over four stages of the developmental cycle. At the lowest H(2)SeO(3) dose (0.05mMkg(-1)), the wheat plants took up much more selenium than did the oilseed rape plants, while the amount of selenium taken up at higher doses (0.15 and 0.45mMkg(-1)) was markedly higher in rape. The increasing Se content in the wheat to about 10mgkg(-1) (in the dark) and to about 16mgkg(-1) (in the light) was accompanied by a concurrent increase in the ATP content, which remained unchanged in the light-exposed plants, while clearly decreasing in those kept in the dark. On the other hand, the ATP content of the light-exposed oilseed rape was maintained at a stable level to about 10mg Sekg(-1), following which ATP content was observed to decrease. In contrast, the tendency for the ATP content to decrease appeared immediately in the dark. The increasing plant selenium concentration was accompanied by decreased APX activity in wheat, increased activity in oilseed rape, no major change in the dehydroascorbate reductase (DHAR) activity in oilseed rape and a slight increase in wheat to about 8mg Sekg(-1), followed by a reduction. The glutathione reductase (GR) activity in wheat differed from the activity of DHAR; an increase in the selenium content to about 8mgkg(-1) was accompanied by a distinct reduction, while a significant increase was observed at higher selenium contents; in oilseed rape, the activity was observed to increase slightly within a narrow range of selenium contents (up to 5mgkg(-1)), and to decrease thereafter.