Selenium concentration in St. John’s wort ( Hypericum perforatum L.) herb after foliar spraying of young plants under different UV-B radiation levels (original) (raw)
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The Promotive Effect of Selenium on Plant Growth as Triggered by Ultraviolet Irradiation
Journal of Environmental Quality, 1999
Selenium is known to be important in antioxidation in human and animals, but little attention has been paid to its role in higher plants. Chemically it is a photovoltaic element, and in order to study its effects on plants, ryegrass (Lolium perenne L.) and lettuce (Lactuca sativa L.) were cultivated in a pot experiment without or with H2SeO4 (0.1 and 1.0 mg Se kg−1) under normal light or subjected to UV(B)‐irradiation episodes. Without Se addition, UV(B) diminished markedly the yield of lettuce (by 8%) but not that of ryegrass. The lower Se dosage had no effect on yields under normal light conditions, but in combination with UV(B) it enhanced plant growth. This indicates that UV light acted as a trigger for the growth‐promoting effect of Se. The higher Se dosage was toxic to plants, but the toxicity was alleviated under UV(B). The positive interaction between the high‐energy light and Se was manifested also as increased concentrations of nucleic acids and soluble proteins. The syner...
Antioxidant Responses of Wheat Seedlings to Exogenous Selenium Supply Under Enhanced Ultraviolet-B
Biological Trace Element Research, 2009
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 (O 2 − ) 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 O 2 − 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.
Food Chemistry, 2006
Common (Fagopyrum esculentum Moench) and tartary (Fagopyrum tataricum Gaertn.) buckwheat was treated by spraying the leaves with a water solution containing 15 mg Se per litre in the form of sodium selenate in the flowering period. The selenium content in all parts of plant was found to be less than 200 ng g À1 in non-treated and in the range 2700-4650 ng g À1 in selenium treated buckwheat. Exposure to UV-B radiation lead to higher Se accumulation in flowers of both Se enriched cultivars. For speciation analysis enzymatic hydrolysis was carried out, separation and detection of selenium species was performed by high performance liquid chromatography-ultraviolet treatment-hydride generation atomic fluorescence spectrometry (HPLC-UV-HG-AFS). In flowers and leaves, on average 11% of the Se content was soluble and in the form of Se(VI), representing between 0.6% (flowers) and 3% (leaves) of the Se content. The remaining soluble non-amino acid organic Se was not detected by HPLC-UV-HG-AFS. In seeds 93% of the selenium content was found in the extracts and the main selenium species was SeMet with 93 ± 5% relative to the selenium content.
Photosynthetica, 2005
The combined effects of UV-B irradiation and foliar treatment with selenium on two buckwheat species, common (Fagopyrum esculentum Moench) and tartary [Fagopyrum tataricum (L.) Gaertn.] buckwheat, that underwent different intensity of breeding, were examined. Plants grown outdoors under three levels of UV-B radiation were studied for 9 weeks, from sowing to ripening. At week 7 they were sprayed with solution containing 1 g(Se) m -3 that presumably mitigates UV-B stress. Morphological, physiological, and biochemical parameters of the plants were monitored. Elevated UV-B radiation, corresponding to a 17 % reduction of the ozone layer, induced synthesis of UV absorbing compounds. In both buckwheat species it also caused a reduction in amounts of chlorophyll a during the time of intensive growth, an effect, which was increased in tartary buckwheat in the presence of selenium. The respiratory potential, measured as terminal electron transport system activity, was lower in plants subjected to enhanced UV-B radiation during the time of intensive growth. The effective quantum yield of photosystem 2 was also reduced due to UV-B radiation in both buckwheat species and was mitigated by the addition of Se. Se treatment also mitigated the stunting effect of UV-B radiation and the lowering of biomass in common buckwheat.
Investigation of Photosynthesis Status of Sunflower Plants Up-taking Different Forms of Selenium
Advances in Plants & Agriculture Research, 2016
Consumption of food products low in Selenium (Se) such as China, UK, Europe, Australia and New Zealand can result in a population with a lower daily intake of Se. Hence, there is a need to increase the organic Se concentration in food products in Se-deficient regions. Accordingly, controlling the Se uptake, metabolism, and dynamic changes in plants will be important to reaching to adequate methods for biofortification. In this regard, in present study, chlorophyll fluorescence and photosynthetic parameters of old and young leaves of sunflower plants that had been treated by sodium selenite and sodium selenate at different concentrations in nutrient solution, were measured. The results showed that the response of experimented sunflowers at 0.1 and 0.3 mg L-1 Se VI concentration, for almost all of the considered parameters was significantly better in comparison with controls samples. It means the application of 0.1 and 0.3 mg L-1 Se VI enhanced photosynthesis by increasing the photosynthesis rate (P n) and the transpiration efficiency (E). Also, Se treatment enhanced the activity of the photosynthetic system by increasing F v /F m and F v /F o. Then, present study proves the chlorophyll fluorescence or photosynthetic parameters can be used for determining the sufficiency of Se treatment during the production of sunflower by Se.
Responses of Wheat Roots to Exogenous Selenium Supply Under Enhanced Ultraviolet-B
Biological Trace Element Research, 2009
Effects of selenium (Se) on growth and some physiological traits of roots in wheat (Triticum aestivum L. cv Han NO.7086) seedlings exposed to enhanced ultraviolet-B (UV-B) stress are reported. Responses of roots were different depending on the Se concentration. Compared with the control, root weight of wheat seedlings treated with 1.0 and 2.0 mg Se kg −1 soil increased by 39.47% and 16.28%, respectively. The lower amount Se (0.5 mg kg −1 ) and the higher amount Se treatments (3.0 mg kg −1 ) did not significantly affect on root weight. Se treatments significantly increased root activity, flavonoids and proline content, and activities of peroxidase and superoxide dimutase in wheat roots exposed to enhanced UV-B. In addition, the treatments with 0.5, 1.0, and 2.0 mg Se kg −1 significantly reduced malondialdehyde content and the rate of superoxide radical (O 2 − ) production of roots, whereas the higher amount Se treatment only induced a decrease in the rate of O 2 − production. The results of this study demonstrated that optimal Se supply promoted roots growth of wheat seedlings, and that optimal Se supply could reduce oxidative stress in wheat roots under enhanced UV-B radiation.
Countering UV-B stress in plants: Does selenium have a role?
UV-B radiation on plants is now of major concern to plant biologists due to the threat to productivity in global agriculture because of stratospheric ozone depletion. Quantitative and qualitative predictions attempts of expected effects and the search for a suitable ameliorant or a stress alleviant are being met with mixed outcomes. One of the reasons for this is the complications involved in designing UV stress response experiments. The study of Heijari et al. in this issue has partially resolved this issue by well designed controls. Although the proportion of UV -B stress countering effects of Se in this study was not enough to meet the criteria of Se as an ameliorant. One of the future challenges to understand Se -plant interaction will be to study its potential essentiality to the plants and to unravel the complete picture of interconversion of the Se species within the plant system.
Food Chemistry, 2008
Seeds of common buckwheat (Fagopyrum esculentum) were soaked in water, sodium selenate (5, 10 or 20 mg Se VI /L), or sodium selenite (10 or 20 mg Se IV /L) solutions. Plants grown from soaked seeds were exposed to reduced UV-B radiation, ambient, or enhanced UV-B. The mass fraction of selenium in leaves was much higher in plants obtained from seeds soaked with selenate (up to 185 ng/g) in comparison to selenite (up to 103 ng/g). In plants obtained from seeds soaked in water, regardless of UV-B levels, the highest concentration of selenium was found in leaves, where the values were between 45 and 66 ng Se/g. In buckwheat leaves 44.5-63.6 mg/100 g d.m. of fagopyrin was found, and in stems 14.3-26.4 mg/100 g d.m.; here no influence of seed soaking solution or UV-B exposure was found. The content of total flavonoids in leaves was 7.8-15.9% and in stems 1.4-4.1%.
Agricultural and Food Science
Selenium (Se) is able to defend human and animal cells against UV(B) stress. Higher plants are generally considered not to require Se but to have a low tolerance to it. However, recently it has been demonstrated that Se is able to protect also plants against UV-induced oxidative stress and even to promote the growth of plants subjected to high-energy light. In the present study the effects of Se on antioxidative enzymes possibly associated with this synergistic effect were investigated. Ryegrass and lettuce were grown in soil supplemented with Se at 0, 0.1 or 1.0 mg kg-1 under normal light or subjected to UV episodes. Lipid peroxidation and the changes of antioxidative enzymes were measured at two growing stages. The positive synergistic effect of the lower Se dosage and UV was found to be at least partly associated with the antioxidative role of Se through increased glutathione peroxidase (GSH-Px) and catalase (CAT) activity, whereas ascorbate peroxidase (APX) responded negatively ...