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1.
Juan J. Ríos Begoña Blasco Luís M. Cervilla María M. Rubio-Wilhelmi Juan M. Ruiz Luis Romero 《Plant Growth Regulation》2008,56(1):43-51
Selenium (Se) is considered an essential trace element for animals because of its nutritional and clinical value, including
its special relevance in cancer prevention, and thus Se is at present used in biofortification programmes. However, possible
effects of Se application on S metabolism and plant growth are still not clear. Thus, we analysed the effect that Se application
in two different forms (selenate versus selenite) exerts on the S metabolism in lettuce plants grown for 66 days. Our results
indicate that the application of selenite as opposed to selenate does not affect the foliar concentration of S. With respect
to different enzymes in charge of sulphate (SO42−) assimilation, the ATP-sulphurylase activity varies only with the application of different rates of selenate, while the activity
of O-acetylserine(thiol)lyase (OAS-TL) and serine-acetyltransferase (SAT) increase in activity mainly when selenite is applied.
Finally, the concentration of cysteine (Cys) and total thiols (SH-total), fundamentally in the selenate treatments, increased
with shoot biomass. In conclusion, this study confirms that the form and application rate of Se affects S assimilation, selenate
being the more suitable form to improve effectiveness of the biofortification programme with this trace element. 相似文献
2.
Barbara Hawrylak-Nowak 《Plant Growth Regulation》2013,70(2):149-157
The effects of different concentrations of selenite (2–30 μM) and selenate (2–60 μM) on biomass production, leaf area, and concentrations of photosynthetic pigments in lettuce plants were investigated. On the basis of the obtained results, the threshold of toxicity for the selenite and selenate has been designated. The toxicity thresholds for selenite and selenate were determined at concentrations of 15 and 20 μM, respectively. Next, four selenium (Se) concentrations (2, 4, 6 or 15 μM), below or near the toxicity boundary, have been selected for the lettuce biofortification experiment. In the biofortified plants, the oxidant status (levels of lipid peroxidation and H2O2 concentrations), as well as Se and sulphur (S) accumulation were analysed. In the edible parts of the lettuce, the Se concentration was higher for selenate presence compared to selenite; however, this difference was not as obvious as it was noted in the case of the roots, where selenite application caused the high accumulation of Se. An application of 15 μM Se as selenite caused a decline in the biomass and an intensification of prooxidative processes in the plant’s tissues and as toxic should be excluded from further biofortification experiments. These results indicate that an application of either selenate or selenite to the nutrient solution at concentrations below 15 μM can be used for biofortification of lettuce with Se, evoking better plant growth and not inducing significant changes in the oxidant status, the concentration of assimilation pigments and S accumulation. 相似文献
3.
Begoña Blasco Juan J. Rios Luis M. Cervilla Eva Sánchez-Rodríguez María M. Rubio-Wilhelmi Miguel A. Rosales Juan M. Ruiz Luis Romero 《Journal of Plant Growth Regulation》2010,29(4):477-486
Iodine is vital to human health, and iodine biofortification programs help improve human intake through plant consumption.
There is no research on whether iodine biofortification influences basic plant physiological processes. Because nitrogen (N)
uptake, utilization, and accumulation are determining factors in crop yield, the aim of this work was to establish the effect
of the application of different doses (20, 40, and 80 μM) and forms of iodine (iodate [IO3
−] vs. Iodide [I−]) on N metabolism and photorespiration. For this study we analyzed shoot biomass and the activities of nitrate reductase
(NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT), aspartate aminotransferase (AAT), glutamate
dehydrogenase (GDH), glycolate oxidase (GO), glutamate:glyoxylate aminotransferase (GGAT), serine:glyoxylate aminotransferase
(SGAT), hydroxypyruvate reductase (HR) and catalase (CAT), nitrate (NO3
−), ammonium (NH4
+), organic and total N, amino acids, proteins, serine (ser), malate, and α-ketoglutaric acid in edible lettuce leaves. Application
of I− at doses of at least 40 μM reduced the foliar concentration of NO3
− with no decrease in biomass production, which may improve the nutritional quality of lettuce plants. In contrast, the application
of 80 μM of I− is phytotoxic for lettuce plants, reducing the biomass, foliar concentration of organic N and NO3
−, and NR and GDH activities. HR activity is significantly inhibited with all doses of I−; the least inhibition was at 80 μM. This may involve a decrease in the incorporation of carbonated skeletons from photorespiration
into the Calvin cycle, which may be partially associated with the biomass decrease. Finally, the application of IO3
− increases biomass production, stimulates NO3
− reduction and NH4
+ incorporation (GS/GOGAT), and optimizes the photorespiratory process. Hence, this appears to be the most appropriate form
of iodine from an agronomic standpoint. 相似文献
4.
Uptake of Selenium and its Antioxidant Activity in Ryegrass When Applied as Selenate and Selenite Forms 总被引:10,自引:0,他引:10
Selenium (Se) is an essential micronutrient for animal and human nutrition, but whether it is essential to plants remains
controversial. However, there are increasing experimental evidences that indicate a protective role of Se against the oxidative
stress in higher plants through Se-dependent glutathione peroxidase (GSH-Px) activity. The effects of the Se chemical forms,
selenite and selenate, the rate of their application on shoot Se concentration and their influence on the antioxidative system
of ryegrass (Lolium perenne cv. Aries), through the measurement of GSH-Px activity and lipid peroxidation, were evaluated in an Andisol of Southern Chile.
Moreover, a soil–plant relationship for Se was determined and a simple method to extract available Se from acid soils is proposed.
In a 55-day experiment ryegrass seeds were sown in pots and soil was treated with sodium selenite or sodium selenate (0–10
mg Se kg−1). The results showed that the Se concentration in shoots increased with the application of both selenite and selenate. However,
the highest shoot Se concentrations were obtained in selenate-treated plants. For both sources of Se, there was a significant
positive correlation between the shoot Se concentration and the GSH-Px activity; and the Se-dependence of this enzymatic activity
was related especially with the chemical form of applied Se rather than the Se concentration in plant tissues. Furthermore,
the lipid peroxidation, as measured by Thiobarbituric Acid Reactive Substances (TBARS), decreased at low levels of shoot Se
concentration, reaching the lowest level at approximately 20 mg Se kg−1 in plants and then increased steadily above this level. In addition, the acid extraction method used to evaluate available
Se in soil showed a positive good correlation between soil Se and shoot Se concentrations irrespective of chemical form of
Se applied. 相似文献
5.
Renata Matraszek 《Acta Physiologiae Plantarum》2008,30(3):361-370
The author studied the effect of different nickel concentrations (0, 0.4, 40 and 80 μM Ni) on the nitrate reductase (NR) activity
of New Zealand spinach (Tetragonia expansa Murr.) and lettuce (Lactuca sativa L. cv. Justyna) plants supplied with different nitrogen forms (NO3
−–N, NH4
+–N, NH4NO3). A low concentration of Ni (0.4 μM) did not cause statistically significant changes of the nitrate reductase activity in
lettuce plants supplied with nitrate nitrogen (NO3
−–N) or mixed (NH4NO3) nitrogen form, but in New Zealand spinach leaves the enzyme activity decreased and increased, respectively. The introduction
of 0.4 μM Ni in the medium containing ammonium ions as a sole source of nitrogen resulted in significantly increased NR activity
in lettuce roots, and did not cause statistically significant changes of the enzyme activity in New Zealand spinach plants.
At a high nickel level (Ni 40 or 80 μM), a significant decrease in the NR activity was observed in New Zealand spinach plants
treated with nitrate or mixed nitrogen form, but it was much more marked in leaves than in roots. An exception was lack of
significant changes of the enzyme activity in spinach leaves when plants were treated with 40 μM Ni and supplied with mixed
nitrogen form, which resulted in the stronger reduction of the enzyme activity in roots than in leaves. The statistically
significant drop in the NR activity was recorded in the aboveground parts of nickel-stressed lettuce plants supplied with
NO3
−–N or NH4NO3. At the same time, there were no statistically significant changes recorded in lettuce roots, except for the drop of the
enzyme activity in the roots of NO3
−-fed plants grown in the nutrient solution containing 80 μM Ni. An addition of high nickel doses to the nutrient solution
contained ammonium nitrogen (NH4
+–N) did not affect the NR activity in New Zealand spinach plants and caused a high increase of this enzyme in lettuce organs,
especially in roots. It should be stressed that, independently of nickel dose in New Zealand spinach plants supplied with
ammonium form, NR activity in roots was dramatically higher than that in leaves. Moreover, in New Zealand spinach plants treated
with NH4
+–N the enzyme activity in roots was even higher than in those supplied with NO3
−–N. 相似文献
6.
Halina M. Zbikowska Barbara Wachowicz Tadeusz Krajewski 《Biological trace element research》1997,57(3):259-269
The effects of inorganic selenium (Se) compounds (sodium selenite and selenate) on the activities of glutathione-related enzymes
(glutathione peroxidase, glutathione-S-transferase [GST] and glutathione reductase [GR]) in pig blood platelets were investigated
in vitro. GST activity in blood platelets treated with 10−4
M of selenite was reduced to 50%, whereas no decrease GST activity was observed after the treatment of platelets with the same
dose of selenate. In platelets incubated with physiological doses (10−7, and 10−6
M) of Se compounds, the activity of glutathione peroxidase (GSH-Px) was enhanced (about 20%). GR activity after the exposure
of platelets to tested Se compounds was unaffected. 相似文献
7.
Effect of byproduct,nitrogen fertilizer,and zeolite on phosphate rock dissolution and extractable phosphorus in acid soil 总被引:12,自引:0,他引:12
The relative plant availability of selenate versus selenite depends on the concentrations of competing ions, specifically
sulfate and phosphate, respectively. In solution culture, the concentration of phosphate is typically 100- to 1000-fold greater
than in soil solution, an artifact that could lead to underestimation of the phytoavailability of selenite. A nutrient solution
study was conducted to compare the availability of selenite and selenate to perennial ryegrass (Lolium perenne L. cv. Evening
Shade) and strawberry clover (Trifolium fragiferrum L. cv. O'Conner) at basal concentrations of SO4 (0.5 mM) and PO4 (2 μM) similar to those found in soil solution. Concentrations up to 5 mM SO4 and 200 μM PO4 allowed quantitative comparison of the efficacy of the competing ions. In both species, selenite was more phytotoxic than
selenate, especially for shoot growth. Selenate was less toxic, and tended to preferentially inhibit root growth. Translocation
percentages were much higher with selenate (≥84%) than with selenite (≤47%). A 10-fold increase in sulfate decreased uptake
from selenate by >90% in both species. In ryegrass, 10-fold increases in phosphate caused 30% to 50% decreases in Se accumulation
from selenite, but in clover such decreases only occurred in the roots. Sulfate-selenate antagonisms were thus stronger than
phosphate-selenite antagonisms. Nonetheless, conventional nutrient solutions with millimolar phosphate will significantly
underestimate Se availability from selenite, and moderate levels of sulfate salinity can inhibit selenate uptake sufficiently
to reverse the apparent relative availability of the two forms of Se.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
J.J. Ríos B. Blasco L.M. Cervilla M.A. Rosales E. Sanchez-Rodriguez L. Romero & J.M. Ruiz 《The Annals of applied biology》2009,154(1):107-116
Selenium is considered an essential element for animals. Despite that it has not been demonstrated to be essential for higher plants, it has been attributed with a protective role against reactive oxygen species in plants subjected to stress. In this study, lettuce plants ( Lactuca sativa cv. Philipus) received different application rates (5, 10, 20, 40, 60, 80 and 120 μM) of selenite or selenate, with the aim of testing the effect of Se on the production and detoxification of H2 O2 in non-stressed plants. The results indicate that the form selenate is less toxic than selenite; that is, the plants tolerated and responded positively to this element, and even increasing in growth up to a rate of 40 μM for the form selenate. On the contrary, the application of selenite triggered a higher foliar concentration of H2 O2 and a higher induction of lipid peroxidation [malondialdehyde content and lipoxygenase activity] in comparison to that observed after the selenate application. Also, the plants treated with selenate induced higher increases in enzymes that detoxify H2 O2 , especially ascorbate peroxidase and glutathione (GSH) peroxidase, as well as an increase in the foliar concentration of antioxidant compounds such as ascorbate and GSH. These data indicate that an application of selenate at low rates can be used to prevent the induction in plants of the antioxidant system, thereby improving stress resistance. 相似文献
9.
The impacts of various nitrogen sources, i.e. NO−
3, NH4
+ or NH4NO3 in combination with gaseous NH3, on nitrogen-, carbon- and water-use efficiency and 13C discrimination (δ13C) by plants of the C3 species Triticum aestivum L. (wheat) and the C4 species Zea mays L. (maize) were studied. Triticum aestivum and Z. mays were hydroponically grown with 2 mol · m−3 of N supplied as NO−
3, NH4
+ or NH4NO3 for 21 and 18 d, respectively, and thereafter exposed to gaseous NH3 at 320 μg · m−3 or to ambient air for 7 d. In T. aestivum and Z. mays over a 7-d growth period, nitrogen-use efficiency (NUE) values were influenced by N-sources in the decreasing order NH4NO3-N > NO−
3-N > NH4
+-N and NO−
3-N > NH4NO3-N > NH4
+-N, respectively. Fumigation with NH3 decreased the NUE values of plants grown with any of the N-forms. During 28- and 7-d growth periods, N-sources affected water-use
efficiency (WUE) values in the decreasing order of NH4
+-N > NO−
3-N≈NH4NO3-N in non-fumigated T. aestivum, while fumigation with NH3 increased the WUE of NO−
3-grown plants. There were insignificant effects of N-sources on WUE values of Z. mays over 25- and 7-d growth periods. Furthermore, δ13C values in plant tissues (leaves, stubble and roots) were higher (less negative) in NH4
+-grown plants of T. aestivum and Z. mays than in those supplied with NH4NO3 or NO−
3. Regardless of the N-form supplied to the roots of the plant species, exposure to NH3 caused more-positive δ13C values in the plant tissues. These results indicate that the variations in N-source were associated with small but significant
variations in δ13C values in plants of T. aestivum and Z. mays. These differences in δ13C values are in the direction expected from differences in WUE values over long or short growth periods and with differences
in the extent of non-Rubisco (ribulose-1,5-bisphosphate carboxylase-oxygenase, EC 4.1.1.39) carboxylate contribution to net
C acquisition, as a function of N-source.
Received: 12 September 1997 / Accepted: 13 January 1998 相似文献
10.
Hunter WJ 《Current microbiology》2006,53(3):244-248
Vegetable oil–based permeable reactive biobarriers (PRBs) were evaluated as a method for remediating groundwater containing
unacceptable amounts of selenate. PRBs formed by packing laboratory columns with sand coated with soybean oil were used. In
an initial 24-week study a simulated groundwater containing 10 mg L−1 selenate-Se was supplied to three soil columns and the selenate and selenite content of the effluent waters monitored. Two
of the soil columns were effective at removing selenate and, during the final 21 weeks of the study, effluents from these
columns contained almost no selenate or selenite. Almost all (95%) of the selenate removed was recovered as immobilized selenium
sequestered in the solid matrix of the column. For unknown reasons, the third column failed to reduce selenate. A second study
looked at the ability of PRBs to remove selenate when nitrate was present. As was done in the first study, three columns were
evaluated but this time the water supplied to the columns contained 20 mg L−1 nitrate-N and 10 mg L−1 selenate-Se. Nitrate quickly disappeared from the effluents of these columns and during the final 23 weeks of the study,
the nitrate content of the effluent water averaged less than 0.03 μg ml−1 nitrate-N. Selenate was also removed by these columns but at a slower rate than observed with nitrate. In the final 6 weeks
of the study, about 95% of the selenate applied to the columns was removed. In situ PRBs containing soybean oil might be used
to remediate groundwater contaminated with both selenate and nitrate. 相似文献
11.
Nitrogen use efficiencies of spring barley grown under varying nitrogen conditions in the field and growth chamber 总被引:3,自引:0,他引:3
Perrin H. Beatty Yadeta Anbessa Patricia Juskiw Rebecka T. Carroll Juan Wang Allen G. Good 《Annals of botany》2010,105(7):1171-1182
Background and Aims
Nitrogen-use efficiency (NUE) of cereals needs to be improved by nitrogen (N) management, traditional plant breeding methods and/or biotechnology, while maintaining or, optimally, increasing crop yields. The aims of this study were to compare spring-barley genotypes grown on different nitrogen levels in field and growth-chamber conditions to determine the effects on N uptake (NUpE) and N utilization efficiency (NUtE) and ultimately, NUE.Methods
Morphological characteristics, seed yield and metabolite levels of 12 spring barley (Hordeum vulgare) genotypes were compared when grown at high and low nitrogen levels in field conditions during the 2007 and 2008 Canadian growing seasons, and in potted and hydroponic growth-chamber conditions. Genotypic NUpE, NUtE and NUE were calculated and compared between field and growth-chamber environments.Key Results
Growth chamber and field tests generally showed consistent NUE characteristics. In the field, Vivar, Excel and Ponoka, showed high NUE phenotypes across years and N levels. Vivar also had high NUE in growth-chamber trials, showing NUE across complex to simplistic growth environments. With the high NUE genotypes grown at low N in the field, NUtE predominates over NUpE. N metabolism-associated amino acid levels were different between roots (elevated glutamine) and shoots (elevated glutamate and alanine) of hydroponically grown genotypes. In field trials, metabolite levels were different between Kasota grown at high N (elevated glutamine) and Kasota at low N plus Vivar at either N condition.Conclusions
Determining which trait(s) or gene(s) to target to improve barley NUE is important and can be facilitated using simplified growth approaches to help determine the NUE phenotype of various genotypes. The genotypes studied showed similar growth and NUE characteristics across field and growth-chamber tests demonstrating that simplified, low-variable growth environments can help pinpoint genetic targets for improving spring barley NUE. 相似文献12.
Selenium uptake and its influence on the antioxidative system of white clover as affected by lime and phosphorus fertilization 总被引:7,自引:0,他引:7
Selenium (Se) is regarded as an antioxidant in animal and human nutrition, but its biological role in plants needs to be clarified.
Plants vary considerably in their ability to tolerate Se, and their biochemical response to Se may be affected by liming or
P fertilization. Two greenhouse experiments were conducted with white clover (Trifolium repens L.) to evaluate Se accumulation, tolerance, and the antioxidant response at increasing selenite supply levels (from 0 to
60 g Se ha−1) and the effect of lime and P on both the Se uptake and the antioxidant activity of plants treated with 0, 20 and 40 g Se
ha−1. Selenium concentration in plant tissues was increased by Se applications, and plant growth was reduced at Se supply levels
above 20 g ha−1. At shoot concentration up to 200 μg kg−1 DW, Se promoted antioxidant ability by increasing the free radical scavenging activity and by inhibiting lipid peroxidation
(TBARS), whereas above this level TBARS accumulation increased. Significant changes in the activities of peroxidase (POD)
and ascorbate peroxidase (APX) enzymes were also observed as a consequence of the increase in shoot Se concentration. The
application of lime and P improved the plant nutrition, which increased the dry matter yield and enhanced the plant’s antioxidative
system. Under different combinations of soil acidity and P fertilization a differential uptake of Se by the plant occurred.
These factors appear to be responsible for beneficial or detrimental effects of Se in terms of lipid peroxidation of biological
membranes and the activation of POD and APX in white clover. 相似文献
13.
Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging
from 1 to 25 μg g−1 soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g−1 soil in raya and maize; 4 μg Se g−1 soil in wheat and 10 μg Se g−1 soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to
be 104.8 μg g−1 in raya, 76.9 μg g−1 in maize, 41.5 μg g−1 in rice and 18.9 μg g−1 in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry
matter yield of raya as well as rice (r = −0.99, P ≤ 0.01), wheat (r = −0.97, P ≤ 0.01) and maize ((r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P ≤ 0.01), wheat (r = 0.89, P ≤ 0.01), rice (r = 0.85, P ≤ 0.01) and maize (r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg−1) when the soil was treated with more than 1.5 μg Se g−1. In case of wheat, application of Se more than 3 μg g−1 soil resulted in production of toxic plants. 相似文献
14.
Supplying both N forms (NH4
++NO3
−) to the maize (Zea mays L.) plant can optimize productivity by enhancing reproductive development. However, the physiological factors responsible
for this enhancement have not been elucidated, and may include the supply of cytokinin, a growth-regulating substance. Therefore,
field and gravel hydroponic studies were conducted to examine the effect of N form (NH4
++NO3
− versus predominantly NO3
−) and exogenous cytokinin treatment (six foliar applications of 22 μM 6-benzylaminopurine (BAP) during vegetative growth versus untreated) on productivity and yield of maize. For untreated plants,
NH4
++NO3
− nutrition increased grain yield by 11% and whole shoot N content by 6% compared with predominantly NO3
−. Cytokinin application to NO3
−-grown field plants increased grain yield to that of NH4
++NO3
−-grown plants, which was the result of enhanced dry matter partitioning to the grain and decreased kernel abortion. Likewise,
hydroponically grown maize supplied with NH4
++NO3
− doubled anthesis earshoot weight, and enhanced the partitioning of dry matter to the shoot. NH4
++NO3
− nutrition also increased earshoot N content by 200%, and whole shoot N accumulation by 25%. During vegetative growth, NH4
++NO3
− plants had higher concentrations of endogenous cytokinins zeatin and zeatin riboside in root tips than NO3
−-grown plants. Based on these data, we suggest that the enhanced earshoot and grain production of plants supplied with NH4
++NO3
− may be partly associated with an increased endogenous cytokinin supply. 相似文献
15.
Selenium accumulation in lettuce germplasm 总被引:1,自引:0,他引:1
Selenium (Se) is an essential micronutrient for animals and humans. Increasing Se content in food crops offers an effective
approach to reduce the widespread selenium deficiency problem in many parts of the world. In this study, we evaluated 30 diverse
accessions of lettuce (Lactuca sativa L.) for their capacity to accumulate Se and their responses to different forms of Se in terms of plant growth, nutritional
characteristics, and gene expression. Lettuce accessions responded differently to selenate and selenite treatment, and selenate
is superior to selenite in inducing total Se accumulation. At least over twofold change in total Se levels between cultivars
with high and low Se content was found. Synergistic relationship between Se and sulfur accumulation was observed in nearly
all accessions at the selenate dosage applied. The change in shoot biomass varied between lettuce accessions and the forms
of Se used. The growth-stimulated effect by selenate and the growth-inhibited effect by selenite were found to be correlated
with the alteration of antioxidant enzyme activities. The different ability of lettuce accessions to accumulate Se following
selenate treatment appeared to be associated with an altered expression of genes involved in Se/S uptake and assimilation.
Our results provide important information for the effects of different forms of Se on plant growth and metabolism. They will
also be of help in selecting and developing better cultivars for Se biofortification in lettuce. 相似文献
16.
B. Blasco J. J. Rios R. Leyva R. Melgarejo C. Constán-Aguilar E. Sánchez-Rodríguez M. M. Rubio-Wilhelmi L. Romero J. M. Ruiz 《Plant Growth Regulation》2011,65(1):137-143
Iodine, essential to human life, is in part ingested through vegetable consumption, explaining the current application of
this element in biofortification programs. Few data are available on the effects of iodine on main plant metabolisms such
as carbon metabolism. The objective of this study was to determine the effect of the application of different doses (20, 40
and 80 μM) and forms of iodine (iodate [IO3
−] and iodide [I−]) on photosynthesis and carbohydrate metabolism in lettuce plants. None of these treatments exerted significant effects on
the synthesis pathway or on sucrose degradation. Application of 80 μM of I− reduced the photosynthesis rate, which may be associated with the reduction found in biomass and photosynthetic parameters
(stomatic conductance and transpiration). This finding confirms that the application of high doses of I− has a phytotoxic effect on plant physiology. In contrast, all IO3
− treatments increased the biomass of the plants which showed an elevated photosynthetic rate, stomatic conductance, and transpiration
(vs. controls). The differential crop behavior observed with the two forms of this trace element suggests that IO3
− should be selected for future biofortification programs. 相似文献
17.
M. Vuletić V. Hadži-Tašković Šukalović K. Marković J. Dragišić Maksimović 《Biologia Plantarum》2010,54(3):530-534
The activities of antioxidative enzymes and contents of proline and total phenolics were assayed in roots of two maize (Zea mays L.) genotypes grown in a medium containing nitrate (NO3
−) or both nitrogen forms, nitrate and ammonium (NH4
+/NO3
−). An increase in the activities of class III peroxidases (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), ascorbate
oxidase (AO) and proline content, and decrease in phenolic content were observed in NH4
+/NO3
− in comparison with NO3
− grown plants. When polyethylene glycol (PEG) was added to both nitrogen treatments, the content of total phenolics and proline
was increased, especially in NH4
+/NO3
− treatment. The PEG treatment decreased enzyme activities in NH4
+/NO3
− grown plants, but in NO3
− grown plants activities of POD and SOD were increased, opposite to decreased APX and AO. Isoelectric focusing demonstrated
increased activities of acidic POD isoforms in PEG treated NO3
− grown plants, and lower activities of both, acidic and basic isoforms in NH4
+/NO3
−grown plants. 相似文献
18.
Begoña Blasco Juan Jose Ríos Rocío Leyva Luis Miguel Cervilla Eva Sánchez-Rodríguez María Mar Rubio-Wilhelmi Miguel Angel Rosales Juan Manuel Ruiz Luis Romero 《Biological trace element research》2011,142(3):831-842
Plants produce low levels of reactive oxygen species (ROS), which form part of basic cell chemical communication; however,
different types of stress can lead to an overexpression of ROS that can damage macromolecules essential for plant growth and
development. Iodine is vital to human health, and iodine biofortification programs help improve the human intake through plant
consumption. This biofortification process has been shown to influence the antioxidant capacity of lettuce plants, suggesting
that the oxidative metabolism of the plant may be affected. The results of this study demonstrate that the response to oxidative
stress is variable and depends on the form of iodine applied. Application of iodide (I−) to lettuce plants produces a reduction in superoxide dismutase (SOD) activity and an increase in catalase (CAT) and L-galactono
dehydrogenase enzyme activities and in the activity of antioxidant compounds such as ascorbate (AA) and glutathione. This
did not prove a very effective approach since a dose of 80 μM produced a reduction in the biomass of the plants. For its part,
application of iodate (IO3−) produced an increase in the activities of SOD, ascorbate peroxidase, and CAT, the main enzymes involved in ROS detoxification;
it also increased the concentration of AA and the regenerative activities of the Halliwell–Asada cycle. These data confirm
the non-phytotoxicity of IO3− since there is no lipid peroxidation or biomass reduction. According to our results, the ability of IO3− to induce the antioxidant system indicates that application of this form of iodine may be an effective strategy to improve
the response of plants to different types of stress. 相似文献
19.
The antimutagenic effect of selenium as sodium selenite, sodium selenate, selenium dioxide, and seleno-methionine was studied
in the AmesSalmonella/microsome mutagenicity test using 7,12-dimethylbenz(a)anthracene (DMBA) and some of its metabolites. Selenium (20 ppm) as
sodium selenite reduced the number of histidine revertants on plates containing up to 100 μg DMBA/plate. Increasing concentrations
of selenium as sodium selenite, sodium selenate, and selenium dioxide up to 40 ppm Se progressively decreased the number of
revertants caused by 50 μg DMBA. DMBA and its metabolites 7-hydroxymethyl-12-methylbenz(a)anthracene, 12-hydroxymethyl-7-methylbenz(a)anthracene,
and 3-hydroxy-7,12-dimethylbenz(a)anthracene were mutagenic forSalmonella typhimurium TA100 in the presence of an S-9 mixture. Selenium supplementation as Na2SeO3 reduced the number of revertants induced by these metabolites to background levels. The antimutagenic effect of inorganic
selenium compounds cannot be explained by toxicity of selenium as determined by viability tests withSalmonella typhimurium TA100. Selenium supplementation in all forms examined, except sodium selenate, decreased the rate of spontaneous reversion.
Selenium as sodium selenate was slightly mutagenic at concentrations of 4 ppm or less. Higher concentration of Na2SeO4 inhibited the mutagenicity of DMBA. The present studies support the anticarcinogenic potential of selenium and indicate that
form and concentration are important factors in this trace element's efficacy. 相似文献
20.
Wetlands are often highly effective nitrogen (N) sinks. In the Lake Waco Wetland (LWW), near Waco, Texas, USA, nitrate (NO3−) concentrations are reduced by more than 90% in the first 500 m downstream of the inflow, creating a distinct gradient in
NO3− concentration along the flow path of water. The relative importance of sediment denitrification (DNF), dissimilatory NO3− reduction to ammonium (DNRA), and N2 fixation were examined along the NO3− concentration gradient in the LWW. “Potential DNF” (hereafter potDNF) was observed in all months and ranged from 54 to 278 μmol N m−2 h−1. “Potential DNRA” (hereafter potDNRA) was observed only in summer months and ranged from 1.3 to 33 μmol N m−2 h−1. Net N2 flux ranged from 184 (net denitrification) to −270 (net N2 fixation) μmol N m−2 h−1. Nitrogen fixation was variable, ranging from 0 to 426 μmol N m−2 h−1, but high rates ranked among the highest reported for aquatic sediments. On average, summer potDNRA comprised only 5% (±2%
SE) of total NO3− loss through dissimilatory pathways, but was as high as 36% at one site where potDNF was consistently low. Potential DNRA
was higher in sediments with higher sediment oxygen demand (r
2 = 0.84), and was related to NO3− concentration in overlying water in one summer (r
2 = 0.81). Sediments were a NO3− sink and accounted for 50% of wetland NO3− removal (r
2 = 0.90). Sediments were an NH4+ source, but the wetland was often a net NH4+ sink. Although DNRA rates in freshwater wetlands may rival those observed in estuarine systems, the importance of DNRA in
freshwater sediments appears to be minor relative to DNF. Furthermore, sediment N2 fixation can be extremely high when NO3− in overlying water is consistently low. The data suggest that newly fixed N can support sustained N transformation processes
such as DNF and DNRA when surface water inorganic N supply rates are low. 相似文献