Intensity Of UV-B Radiation Research Articles

Exposure to UV-B Radiation Leads to Increased Deposition of Cell Wall-Associated Xerocomic Acid in Cultures of Serpula himantioides.

Many fungi are thought to have developed morphological and physiological adaptations to cope with exposure to UV-B radiation, but in most species, such responses and their protective effects have not been explored. Here, we study the adaptive response to UV-B radiation in the widespread, saprotrophic fungus Serpula himantioides, frequently found colonizing coniferous wood in nature. We report the morphological and chemical responses of S. himantioides to controlled intensities of UV-B radiation, under in vitro culture conditions. Ultraviolet radiation induced a decrease in the growth rate of S. himantioides but did not cause gross morphological changes. Instead, we observed accumulation of pigments near the cell wall with increasing intensities of UV-B radiation. Nuclear magnetic resonance (NMR) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses revealed that xerocomic acid was the main pigment present, both before and after UV-B exposure, increasing from 7 mg/liter to 15 mg/liter after exposure. We show that xerocomic acid is a photoprotective metabolite with strong antioxidant abilities, as evidenced by DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt], and oxygen radical absorbance capacity (ORAC) assays. Finally, we assessed the capacity of xerocomic acid as a photoprotective agent on HEK293 cells and observed better photoprotective properties than those of β-carotene. Xerocomic acid is therefore a promising natural product for development as a UV-protective ingredient in cosmetic and pharmaceutical products.IMPORTANCE Our study shows the morphological and chemical responses of S. himantioides to controlled doses of UV-B radiation under in vitro culture conditions. We found that increased biosynthesis of xerocomic acid was the main strategy adopted by S. himantioides against UV-B radiation. Xerocomic acid showed strong antioxidant and photoprotective abilities, which has not previously been reported. Our results indicate that upon UV-B exposure, S. himantioides decreases its hyphal growth rate and uses this energy instead to increase the biosynthesis of xerocomic acid, which is allocated near the cell wall. This metabolic switch likely allows xerocomic acid to efficiently defend S. himantioides from UV radiation through its antioxidant and photoprotective properties. The findings further suggest that xerocomic acid is a promising candidate for development as a cosmetic ingredient to protect against UV radiation and should therefore be investigated in depth in the near future both in vitro and in vivo.

Effect of UV-B radiations on mortality and enzymes level in fish larvae of Tor tor and Schizothorax richardsonii on laboratory scale

Depletion of stratospheric ozone layer is resulting into increase in solar UV-B on earth surface. Ultra violet radiation is well known to cause many detrimental effects in aquatic organisms. The present study was performed to study the effect of solar ultraviolet radiation on fish fingerlings of Tor tor and Schizothorax richardsonii as a model system on laboratory scale. The effect of different intensities of natural solar and artificial UV-B radiation on fish larvae of T. tor and S. richardsonii in a presence of retene was investigated. Solar ultraviolet intensity showed seasonal and altitudinal variations in Garhwal region. Solar UV radiation level was lower (0.390 mw/cm2) in the month of January- February at lower altitude and highest (1.192 mw/cm2) in the month of July-August 2018 at higher altitude. Fish larvae exposed to artificial UV-B (average wavelength 312 nm and intensity of 750 mw/cm2) with retene (50µg/l) showed increase in gills malandialdehyde level and caused larvae mortality as indicating that enhanced solar UV-B exposure could be lethal to fish fauna in aquatic ecosystem. Artificial UV-B had a stronger damaging effect on fish larvae than solar radiation exhibited highly toxic in presence of retene. The larvae of S. richardsonii was found more sensitive than T. tor as indicated by high mortality rate (30%) and high pigmented characteristics on dorsal side. The solar and ultraviolet radiation showed a positive effect on high pigmentation. These results suggest that on a short time scale, UV-B radiation causing developmental stress on fish larvae may contribute to assess the phototoxic behaviour of cold water fishes.

Carryover effects of short-term UV-B radiation on fitness related traits of the sea urchin Strongylocentrotus intermedius

Carryover effects of UV-B radiation are largely unknown in marine invertebrates, despite the ecological importance. For the first time, we investigated fitness related traits of the sea urchin Strongylocentrotus intermedius 8 weeks after short-term (1 h) UV-B radiations (0, 10 and 20 µW cm−2). Short-term UV-B radiations had significant negative effects on survival, food consumption, test diameter, test height, test height:test diameter, gonad weight and crude protein of gonads of S. intermedius, despite of the absence of UV-B radiation for 8 weeks. Survival, food consumption and crude protein of gonads were significantly lowest in S. intermedius exposed to UV-B radiation at 20 µW cm−2, highlighting that 20 µW cm−2 is a dangerous UV-B radiation intensity for the fitness of sea urchins (at least S. intermedius). Gonads were significantly more sensitive to UV-B radiation than the gut. The present study increases our understanding of carryover effects of UV-B radiations on sea urchins and provides valuable information into marine environmental safety.

Hormonal and physiological changes driven by fungal endophytes increase Antarctic plant performance under UV-B radiation

Abstract Antarctic environments are amongst the most stressful habitats for life on Earth, with high intensities of solar UV-B radiation reaching the land surface. In this study, we evaluated how the photochemical efficiency, cell damage and reproductive biomass of Antarctic pearlwort (Colobanthus quitensis) were affected by different intensities of UV-B radiation in the absence and presence of fungal endophytes. In addition, we evaluated the hormonal content of plants at different UV-B radiation intensities and how hormonal content was affected by endophytes. Overall, plants exposed to UV-B radiation showed higher numbers of flowers, higher total biomass and lower lipid peroxidation in the presence of endophytes compared with plants without endophytes. Photochemical efficiency was unaffected. Fungal endophytes affected the content of salicylic acid, jasmonate, indole-3-acetate and abscisic acid in shoot tissue of plants exposed to UV-B radiation. These results suggest that endophytes could modulate the hormonal content of C. quitensis to improve its ecophysiological performance under high UV-B radiation.

Effects of UV-B Radiation on the Content of Bioactive Components and the Antioxidant Activity of Prunella vulgaris L. Spica during Development.

The effects of UV-B radiation on the content of bioactive components and the antioxidant activity of Prunella vulgaris L. spica during development were studied. The experimental design involved two levels of UV-B radiation intensity (0 and 120 μW cm−2 nm−1). The results showed that the contents of total flavonoids, rosmarinic acid, caffeic acid and hyperoside, as well as the antioxidant capacities (DPPH● and ABTS•+ scavenging activities), in the spicas significantly decreased during spica development. The content of salviaflaside in the spicas significantly increased during development. The highest contents of total flavonoids, rosmarinic acid, and caffeic acid and the highest antioxidant activities were found in spicas in the full-flowering stage, while the highest content of hyperoside was found in spicas in the bud stage. In addition, the highest content of salviaflaside was found in spicas in the mature-fruiting stage. UV-B radiation significantly promoted the synthesis of secondary metabolites, increased the contents of the main bioactive components in the three developmental stages of isolated dried spicas, and significantly increased the DPPH● and ABTS•+ scavenging activities of P. vulgaris spicas in the mature-fruiting stage. Moreover, the total flavonoids content was positively correlated with the DPPH● and ABTS•+ scavenging activities, and the correlation with the DPPH● scavenging activity was very strong. This result shows that the highest contents of the main bioactive components in the spicas were not all found in the same developmental stages of P. vulgaris. Our research revealed that the best stage for harvesting P. vulgaris spica was between the bud stage and the full-flowering stage since harvesting at this point provides a higher content of bioactive components and a higher antioxidant capacity, which is relevant for medicinal applications.

Effects of enhanced UV-B radiation on the content of flavonoids in mesophyll cells of wheat

The content of flavonoids in mesophyll cells of wheat was studied under the condition of enhanced UV-B radiation intensity. In this experiment, four groups of six days of control were treated with He-Ne laser group (L), enhanced UV-B radiation group (B), He-Ne laser and UV-B combined treatment group (B + L ), Normal light group (CK). Since the flavonoids carry some unsubstituted hydroxyl or glycosyl groups, it is a polar compound. By the 'similar compatibility' principle, they have some level of solubility in polar solvents, such as methanol, ethanol, n-butanol, propanol, and water. In this experiment, 70% ethanol was used to extract flavonoids. Finally, the total content of flavonoids in mesophyll cells was determined by visible spectrophotometry. The OD value of flavonoids was determined by rutin reagent 'The standard curves because rutin is a representative of flavonoids, it scavenging the role of free radicals significantly. The results showed that when the UV-B UV radiation intensity was enhanced, the content of flavonoids in wheat mesophyll cells increased, that is, the content of flavonoids in wheat leaves was higher than that in UV-B Strength was positively correlated. The results showed that the content of flavonoids in the mesophyll cells of the four control groups was the same as that of the B group> BL group> CK group> L group. With the prolonging of the treatment time of wheat, the content of flavonoids in wheat leaves at jointing-booting stage was significantly higher than that in seedling stage and panicle stage. This means that flavonoids are a protective substance that absorbs UV-B in plants, that is, the absorption of UV-B by flavonoids reduces the damage of UV-B to organs in plants [8] [10]; UV-B The smaller the damage, the less the content of flavonoids; laser damage caused by UV-B have a certain role in the repair. In this study, we further studied the effect of enhanced UV-B radiation on the content of flavonoids in mesophyll cells of wheat. The effects of UV-B radiation on the content of flavonoids in wheat were studied. Whether it has a very important significance for wheat has become a stress [5].

Effects of UV-B radiation on the isoflavone accumulation and physiological-biochemical changes of soybean during germination: Physiological-biochemical change of germinated soybean induced by UV-B

In this study, the effects of UV-B radiation on the isoflavones accumulation, physiological and nutritional quality, water status, and characteristics of proteins in germinated soybeans were investigated. The results showed that isoflavones content in soybeans increased with appropriate intensity and time of UV-B radiation and decreased with excessive treatment. Fresh weight, length, free amino acids, reducing sugar contents and bulk water (T23) in germinated soybeans decreased with increasing radiation time, indicating that UV-B inhibited the growth and nutrients metabolism of soybean during germination. Cell damage was detected in germinated soybeans with excessive UV-B radiation, as shown by the black spots in cotyledons and the increased intercellular water determined by LF-NMR. Germination resulted in an increase in random coil structures, while UV-B radiation induced no obvious changes in FT-IR spectrum and protein conformation of soybeans. Both UV-B radiation and germination caused the increase in soluble proteins, especially in 1.0–75.0 kDa fraction.

Effects of enhanced UV-B radiation on photosynthetic physiology and chloroplast ultrastructure of Phragmites australis

The effects of different intensities of UV-B radiation on photosynthetic characteristics, photosynthetic pigment content and chloroplast ultrastructure of Phragmites australis were studied in this paper. The results showed that enhanced UV-B radiation significantly reduced the net photosynthetic rate, stomatal conductance and transpiration rate, and the degree of degradation increased with the increasing irradiation intensity. The intercellular CO2 content increased and the photosynthetic efficiency decreased significantly compared with the control. Enhanced UV-B radiation decreased photosynthetic pigment contents, including chlorophyll a, chlorophyll b, total chlorophyll and carotenoid, and the decrement increased with the increasing irradiation intensity. Under the enhanced UV-B radiation treatment, chloroplast structure was damaged, and thylakoid lamellae was disorde-red, swelling and even blurred. The effect of high intensity of radiation on chloroplast ultrastructure was greater than that of lower intensity of radiation.

UV-B长期胁迫对麦长管蚜子代种群动态的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 UV-B长期胁迫对麦长管蚜子代种群动态的影响 DOI: 10.5846/stxb201611172338 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（39970112，20470268）；高校博士点基金（20130204110004）；陕西省科技厅国际合作项目（2012） Effect on population dynamics of the offspring of Sitobion avenae Fabricius (Hemiptera: Aphididae) exposed to long term UV-B stress Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了探明UV-B长期辐射亲代麦长管蚜Sitobion avenae Fabricius后对其子代种群动态的影响。采用特定年龄生命表方法，设置不同强度（0，0.50，0.70 mW/cm2）UV-B连续多代处理麦长管蚜成虫，统计麦长管蚜分别经历UV-B辐射一代，六代，十一代，十五代后其子代麦长管蚜存活率和繁殖力、繁殖参数、种群参数的变化。结果表明：（1）经UV-B处理亲代麦长管蚜后，其子代种群的内禀增长率r与周限增长率λ在低强度处理组各世代之间无显著差异，在高强度处理组各世代之间呈先上升后下降的趋势。（2）处理组麦长管蚜种群繁殖力F、净增殖率R0、平均世代周期T、产卵天数和成蚜寿命均在G7代达到最大值，且与对照组无显著差异。（3）亲代麦长管蚜经UV-B胁迫处理后对子代种群的存活率影响显著。研究结论：亲代麦长管蚜经过不同代数的UV-B胁迫，可显著影响子代的生长发育与繁殖，且对处于不同世代的子代生态学指标产生不同影响。研究的创新点在于探究亲代麦长管蚜经历紫外胁迫后对其子代生长、发育与繁殖的影响，为逆境胁迫下蚜虫的生态遗传与进化机理提供理论依据。 Abstract:Recently, ultraviolet-B radiation (UV-B) has been proven to have a strong selection pressure on the biosphere and ecological environment, significantly influencing living organisms. The rapid increase of solar UV-B reaching the surface of the earth is owing to stratospheric ozone depletion caused primarily by the Industrial Revolution. The responses of insect physioecology and growth to ultraviolet radiation enhancement have received increasing attention in the scientific community. Sitobion avenae Fabricius (Hemiptera:Aphididae) is a common wheat pest. It affects plants by ingesting sap from the ears, stems, leaves, and other tender plant parts. It also transmits viruses (e.g., barley yellow dwarf virus) during feeding, thereby reducing wheat yield and quality. It is a good subject for research because of its special characteristics of parthenogenesis and high fecundity. The increase of UV-B levels may fundamentally affect the population dynamics of S. avenae by altering its normal growth, development, and fecundity. The two-sex life table analysis is a common method to indicate biological growth, development, and fecundity, and includes the entire population (males, females, and those that die before the adult stages), so that the result is more realistic than analyses based only on the means of development time. To explore the effect on population dynamics of the offspring of S. avenae by exposing the mother generation to UV-B for a long time, the age-specific life table of S. avenae was established to evaluate life-table parameters of offspring of S. avenae. The mother generation was radiated to different intensities of UV-B (0, 0.5, 0.7 mW/cm2) for one, six, eleven, and fifteen generations. The results showed that:(1) There were no significant differences in the intrinsic rate of increase (r) and finite rate of increase (λ) among the treatment group of each generation under low intensity of UV-B, whereas the parameters of r and λ first increased and then fell with generations under high intensity of UV-B. (2) The effect of UV-B on the fecundity (F), net reproductive rate (R0), mean generation time (T), oviposition duration, and adult longevity peaked in the seventh generation. Moreover, no significant difference was found in the seventh generation between the control and treatment groups. (3) When S. avenae were under different intensity of UV-B radiation in the same generation, most parameters in the treatments groups were significantly lower than those in the control except the parameter T in the second and sixteenth generation. However, no significant difference was found in the seventh generation between the control groups and treatment groups, whereas F, R0, T, oviposition days, and adult longevity all had significant differences, but there were no significant differences between other parameters in the twelfth generation. (4) The survival rate of offspring of S. avenae exposed to UV-B stress was significantly influenced. Our research showed that the effect of long-term UV-B stress on S. avenae was accumulated in the progeny, had different impacts in different generations. Our research showed the population dynamics of the offspring of S. avenae after the mother generation was influenced by UV-B; thus, the results may provide a theoretical basis for ecological genetics and evolutionary mechanisms of aphid under adversity stress. 参考文献 相似文献 引证文献

Overlapping Leaves Covering Flowers in the Alpine Species Eriophyton wallichii (Lamiaceae): Key Driving Factors and Their Potential Impact on Pollination

Extrafloral structures are supposed to have evolved to protect flowers from harsh physical environments but might have effects on pollination. Overlapping leaves cover flowers in Eriophyton wallichii, an alpine perennial endemic to the Himalaya-Hengduan Mountains. In previous study, it has showed that these extrafloral leaves can protect interior flowers from temperature fluctuations caused by drastic solar radiation fluctuations, but these leaves may also protect interior flowers from rain wash and UVB damage, and we do not know which one is the main function. In this study, we investigated whether rain and UVB protection are the main functions of overlapping leaves covering flowers and their potential impact on pollination. We first measured the intensities of UVB radiation in open air, beneath leaves and corollas, and then examined pollen susceptibility to different intensities of UVB and rain in the laboratory to estimate whether corollas per se protect interior pollen from UVB and rain damage. We also carried out pollination treatments and observed pollinator visitation of flowers with and without leaves in the field to assess whether the overlapping leaves covering flowers impair pollinator attraction. Our results showed that (1) water and strong UVB significantly decreased pollen germinability, but corollas per se could protect pollen from UVB and rain damage; (2) no autonomous self-pollination and apomixis occurred, and pollinators were essential for the reproduction of E. wallichii; however, flower coverage by overlapping leaves did not limit pollination. We suggested that rain and UVB protection was not the main function of overlapping leaves covered flowers, given that this protection can be provided by corollas per se. Alternatively, this extrafloral structure in E. wallichii may have evolved in response to extreme high temperatures associated with the strong solar radiation fluctuations. This indicates that, even in alpine plants, extreme high temperature may affect the evolution of plant extrafloral structures.

Surface Ozone Concentration and Its Relationship with UV Radiation, Meteorological Parameters and Radon on the Eastern Coast of the Baltic Sea

Hourly and daily variations of ground-level ozone have been analyzed in relation to meteorological parameters, UVB radiation and radon near the Baltic Sea in Lithuania. An atypical situation with respect to wind domination was observed during the experiment: the wind from the continent was twice as frequent as the wind from the sea. The close correlation between ground-level ozone concentration and UVB radiation intensity was established. The vertical migration directions of ozone and radon were opposite and the negative correlation between these pollutants was observed. The diurnal course of ozone and radon and the influence of meteorological parameters (temperature, relative air humidity, wind speed and direction) on variation of these pollutants have been estimated. It was established that the wind direction domination during the experiment had a significant influence on the variation of ozone and radon concentrations.

UV-B Exposure Affects the Biosynthesis of Microcystin in Toxic Microcystis aeruginosa Cells and Its Degradation in the Extracellular Space.

Microcystins (MCs) are cyclic hepatotoxic heptapeptides produced by cyanobacteria that can be toxic to aquatic and terrestrial organisms. MC synthesis and degradation are thought to be influenced by several different physical and environmental parameters. In this study, the effects of different intensities of UV-B radiation on MC biosynthesis in Microcystis cells and on its extracellular degradation were investigated by mRNA analysis and degradation experiments. Exposure to UV-B at intensities of 1.02 and 1.45 W/m2 not only remarkably inhibited the growth of Microcystis, but also led to a decrease in the MC concentration. In addition, mcyD transcription was decreased under the same UV-B intensities. These results demonstrated that the effects of UV-B exposure on the biosynthesis of MCs in Microcystis cells could be attributed to the regulation of mcy gene transcription. Moreover, the MC concentration was decreased significantly after exposure to different intensities of UV-B radiation. Of the three MC variants (MC-LR, -RR and -YR, L, R and Y are abbreviations of leucine, arginine and tyrosine), MC-LR and MC-YR were sensitive to UV-B radiation, whereas MC-RR was not. In summary, our results showed that UV-B radiation had a negative effect on MC production in Microcystis cells and MC persistence in the extracellular space.

Effects of UV-B on Environmental Preference and Egg Parasitization byTrichogrammaWasps (Hymenoptera: Trichogrammatidae)

Abstract The intensity of ultraviolet (UV) radiation varies widely in space, both across the globe and over small spatial scales (a few millimeters), depending on patterns of light and shade. Gradients of UV radiation can control the movement of organisms on landscapes and how the organisms perform. It is likely that insects are at high risk from UV radiation because of their small size; radiation may penetrate significantly deeper into insect tissues than into larger organisms, thereby disproportionately affecting their performance. We investigated the effects of UV radiation on the behavior and parasitism success of the agriculturally important egg parasitoid wasp, Trichogramma spp. We found that Trichogramma preferred to move toward higher intensities of UV-B radiation and parasitized more eggs in areas with higher UV-B radiation. However, higher UV-B radiation reduced the number of adult wasps emerging from host eggs. Trichogramma reproductive behavior may, therefore, be maladaptive depending on envi...

Characterization of satellite-based proxies for estimating nucleation mode particles over South Africa

Abstract. Proxies for estimating nucleation mode number concentrations and further simplification for their use with satellite data have been presented in Kulmala et al. (2011). In this paper we discuss the underlying assumptions for these simplifications and evaluate the resulting proxies over an area in South Africa based on a comparison with a suite of ground-based measurements available from four different stations. The proxies are formulated in terms of sources (concentrations of precursor gases (NO2 and SO2) and UVB radiation intensity near the surface) and a sink term related to removal of the precursor gases due to condensation on pre-existing aerosols. A-Train satellite data are used as input to compute proxies. Both the input data and the resulting proxies are compared with those obtained from ground-based measurements. In particular, a detailed study is presented on the substitution of the local condensation sink (CS) with satellite aerosol optical depth (AOD), which is a column-integrated parameter. One of the main factors affecting the disagreement between CS and AOD is the presence of elevated aerosol layers. Overall, the correlation between proxies calculated from the in situ data and observed nucleation mode particle number concentrations (Nnuc) remained low. At the time of the satellite overpass (13:00–14:00 LT) the highest correlation is observed for SO2/CS (R2 = 0.2). However, when the proxies are calculated using satellite data, only NO2/AOD showed some correlation with Nnuc (R2 = 0.2). This can be explained by the relatively high uncertainties related especially to the satellite SO2 columns and by the positive correlation that is observed between the ground-based SO2 and NO2 concentrations. In fact, results show that the satellite NO2 columns compare better with in situ SO2 concentration than the satellite SO2 column. Despite the high uncertainties related to the proxies calculated using satellite data, the proxies calculated from the in situ data did not better predict Nnuc. Hence, overall improvements in the formulation of the proxies are needed.

Effects of Enhanced UV-B Radiation on Biochemical Traits in Postharvest Flowers of Medicinal Chrysanthemum.

This article reported UV-B radiation effects on biochemical traits in postharvest flowers of chrysanthemum. The experiment included six levels of UV-B radiation (UV0, 0 μW cm(-2); UV50, 50 μW cm(-2); UV200, 200 μW cm(-2); UV400, 400 μW cm(-2); UV600, 600 μW cm(-2) and UV800, 800 μW cm(-2). Enhanced UV-B radiation significantly increased hydrogen peroxide content (except for UV50), but did not evidently affect malondialdehyde content in flowers. Chlorophyll b and total chlorophyll content were significantly increased by UV600 and UV800. UV400 and UV600 significantly increased anthocyanins, carotenoids and UV-B absorbing compounds content, and the activities of phenylalanine ammonia lyase (PAL) and cinnamic acid-4-hydroxylase (C4H) over the control. 4-coumarate CoA ligase (4CL) activity was significantly decreased by enhanced UV-B radiation (except for UV50). The relationships between UV-B radiation intensities and the activities of secondary metabolism enzymes were best described by a second-order polynomial. The R(2) values for UV-B radiation intensities and the activities of PAL, C4H and 4CL were 0.8361, 0.5437 and 0.8025, respectively. The results indicated that enhanced UV-B radiation could promote secondary metabolism processes in postharvest flowers, which might be beneficial for the accumulation of medically active ingredients in medicinal plants. The optimal UV-B radiation intensities in the study were between UV400-UV600.

Carbon allocation from source to sink leaf tissue in relation to flavonoid biosynthesis in variegated Pelargonium zonale under UV-B radiation and high PAR intensity

We studied the specific effects of high photosynthetically active radiation (PAR, 400–700 nm) and ecologically relevant UV-B radiation (0.90 W m−2) on antioxidative and phenolic metabolism by exploiting the green-white leaf variegation of Pelargonium zonale plants. This is a suitable model system for examining “source-sink” interactions within the same leaf. High PAR intensity (1350 μmol m−2 s−1) and UV-B radiation induced different responses in green and white leaf sectors. High PAR intensity had a greater influence on green tissue, triggering the accumulation of phenylpropanoids and flavonoids with strong antioxidative function. Induced phenolics, together with ascorbate, ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (CAT, EC 1.11.1.6) provided efficient defense against potential oxidative pressure. UV-B-induced up-regulation of non-phenolic H2O2 scavengers in green leaf sectors was greater than high PAR-induced changes, indicating a UV-B role in antioxidative defense under light excess; on the contrary, minimal effects were observed in white tissue. However, UV-B radiation had greater influence on phenolics in white leaf sections compared to green ones, inducing accumulation of phenolic glycosides whose function was UV-B screening rather than antioxidative. By stimulation of starch and sucrose breakdown and carbon allocation in the form of soluble sugars from “source” (green) tissue to “sink” (white) tissue, UV-B radiation compensated the absence of photosynthetic activity and phenylpropanoid and flavonoid biosynthesis in white sectors.

绿洲棉田UV-B辐射增强对棉花生长发育的影响

在大田试验条件下，研究UV-B辐射增强对棉花生长发育的影响。通过人工增加对棉花UV-B辐射，设置4个处理，每个处理的辐射剂量分别为0 W/m2 (R0)、0.5 W/m2 (R1)、1.0 W/m2 (R2) 和1.5 W/m2 (R3)，研究了UV-B辐射增强对棉花株高、茎粗、叶面积、叶片表观伤害、产量和品质的影响。结果表明：随着UV-B辐射增强，R1、R2和R3处理组的株高、茎粗、叶面积分别与对照达到了极显著水平(P The objectives of this research were to study the influences of enhanced ultraviolet radiation (UV-B, 280 - 320 nm) on physiological indicator, yield and quality of cotton. We set four treatments of 0 w/m2 (R0), 0.5w/m2 (R1), 1w/m2 (R2), 1.5 w/m2 (R3) by increasing artificial UV-B radiation and studied the effect of enhanced Ultraviolet-B radiation on plant height, stem diameter, leaf area index (LAI), apparent injure in leaf, yield and quality of cotton. The results showed that the plant height, stem diameter and LAI had significant correlation with the increasing Ultraviolet- B radiation (P < 0.01), and the difference between R3 and other treatments also had statistically significance (P < 0.01). The apparent injury in leaf of cotton became more serious and the quantity and quality was also at the lowest level as followed. The relationship between UV-B radiation and cotton growth was closer. The higher intensity of UV-B radiation would have more negative effects on cotton growth.

UV-B辐射和干旱对丹参生长和叶片中酚酸类成分的影响

Ultraviolet B and drought stress are common environmental stresses in arid and semi-arid regions of northwestern China. A pot experiment was conducted to investigate the separate and combined effects of UV-B radiation and drought stress on physiological characteristics of Salvia miltiorrhiza Bunge in this region,and on the accumulation of phenolic compounds in its leaves. In this experiment,the UV-B radiation was performed with two intensities,2.60 k J / m2( T1) and4.10 k J / m2( T2),meanwhile,three gradual drought stress treatments were carried out with field water capacity ranging from40% to 75%. The involved physiological characteristics included plant height,leaf area index,shoot biomass,root biomass,total biomass,root: shoot ratio,and those photosynthetic indices,such as net photosynthetic rate( Pn),transpiration rate( Tr),stomatal conductance( Gs) and intercellular CO2concentration( Ci). The phenolic compounds detected in leaves contained salvianolic acid B( SAB), rosmarinic acid( RA), caffeic acid( CA) and 3,4-trihydroxybenzenepropanoic acid( DSS). The results showed that both UV-B radiation and drought stress had cross-talk on the growth of S. miltiorrhiza,and the least plant height was found in the combined treatment( 40% T2),which significantly decreased 47.82%. Drought stress and UV-B radiation reduced leaf area 40.22% and 71.51%,respectively,and the leastvalue occurred in the combined treatment 75% T2. Similarly,the least root: shoot ratio also happened in combined treatment75% T1 and the least total plant biomass did in 40% T2. In terms of the effects of UV-B and drought stress on photosynthetic indices,similar tendency was observed among Pn,Tr and Gs,but Ci had reverse trend with these three indices. The three indices were found reaching the largest at growth season,but decreased to the lowest at harvest period in the combined 40%T2 treatment. Both UV-B and drought stress could promote the accumulation of four phenolic compounds,in which the former had more prominent influence. Both contents of SAB and RA increased 4.28 and 8 folds,respectively,under UV-B radiation,which were significantly higher than 1. 12 and 1. 51 folds in drought stress treatment. The SAB and RA accumulation reached the highest level( 4.75 and 3.15 μg / g,respectively) in the combined treatment 75% T2. Statistical data also exhibited that there was a cross-talk in accumulation of phenolic compounds between UV-B and drought stress. The SAB content increased 4.28 folds in T2 radiation intensity,while only 2.18 folds were observed in T1. The content increased1.12 and 0.52 folds in drought stress treatment with 40% and 55% field water capacity,respectively. If combined UV-B radiation and drought stress,the SAB content would increased 2. 69 and 1. 67 folds in 40% T2 and 55% T2 treatments,respectively. In conclusion,there was a cross-talk between UV-B radiation and drought stress,which had combined effects on the growth of S. miltiorrhiza and accumulation of phenolic compounds in leaves. Relatively,UV-B radiation had stronger influence than drought stress. Either UV-B radiation or drought stress had negative effect on plant growth. The higher UV-B radiation intensity( T2,4. 10 k J / m2) was helpful to accumulation of SAB,but the amount of accumulation would be decreased with the increase of drought stress intensity.

The effects of UV-B radiation intensity on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum.

The article studied UV-B effects on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum during the bud stage. The experiment included four UV-B radiation levels (CK, ambient UV-B; T1, T2 and T3 indicated a 5%, 10% and 15% increase in ambient UV-BBE, respectively) to determine the optimal UV-B radiation intensity in regulating active ingredients level in flowers of two chrysanthemum varieties. Flower dry weight of two cultivars was not affected by UV-B radiation under experimental conditions reported here. UV-B treatments significantly increased the rate of superoxide radical production, hydrogen peroxide (H2O2) (except for T1) and malondialdehyde concentration in flowers of Huai chrysanthemum and H2O2 concentration in flowers of Qi chrysanthemum. T2 and T3 treatments induced a significant increase in phenylalanine ammonia lyase enzyme (PAL) activity, anthocyanins, proline, ascorbic acid, chlorogenic acid and flavone content in flowers of two chrysanthemum varieties, and there were no significant differences in PAL activity, ascorbic acid, flavone and chlorogenic acid content between the two treatments. These results indicated that appropriate UV-B radiation intensity did not result in the decrease in flower yield, and could regulate PAL activity and increase active ingredients content in flowers of two chrysanthemum varieties.

Effects of UV-B Radiation on the Growth, Physiological and Biochemical Characteristics of &lt;i&gt;Chondrus ocellatus&lt;/i&gt; Holm (Rhodophyta)

Effects of enhanced ultraviolet B (UV-B, 280-320 nm) on macroalgae have gained particular attention in recent years. We investigated the changes in the growth, physiological and biochemical characteristics of C. ocellatus under UV-B radiation in this study. The results showed that UV-B could inhibit the growth of C. ocellatus (p&lt;0.01) and the growth inhibition was more significant with increased doses of UV-B radiation. The effects of UV-B radiation on Chl-a content in C. ocellatus were not obvious. The soluble proteins content and MDA content in C. ocellatus were increased by UV-B radiation, and the increase of MDA content was extraordinary significant. The SOD activity and CAT activity were increased when the intensity of UV-B radiation was 7.2 J/m2, while the SOD activity and CAT activity were decreased when the intensity of UV-B radiation was 21.6 J/m2.