不同氮供应下增强UV-B辐射对谷子叶片重要生理指标的影响

以谷子(Setaria italica(L.)Beauv.)为研究材料,从拔节期开始持续浇灌1.88、15mmol·L-12种氮供应水平营养液,从抽穗期开始对材料进行增强UV-B辐射处理(14.7μW·cm-2),研究了谷子叶片中总叶绿素、可溶性物质及紫外吸收物质的含量在开花期期间的变化。结果表明:与较高氮供应水平相比,无论是否进行增强UV-B辐射,较低氮供应水平明显降低了谷子叶中总叶绿素、可溶性蛋白的含量,但提高了其紫外吸收物质的含量;与较低氮供应水平相比,较高氮供应水平下的谷子叶中总叶绿素含量在开花期初期和中期,可溶性蛋白含量在开花期中期对增强UV-B辐射处理更敏感;氮供应水平虽然对开花期中期至末期的谷子叶片可溶性糖含量有显著影响,但在整个增强UV-B辐射处理期间,该指标对增强UV-B辐射并不敏感。上述结果表明,较低氮供应水平可促进谷子叶片在开花期期间紫外吸收物质的积累,有利于增强其抵抗UV-B辐射能力,但仍应寻求一个合理范围的氮供应水平,以平衡谷子生殖生长和提高对UV-B辐射抗性的需求。     

增强UV-B辐射与不同水平氮素对谷子（Setaria italica (L.) Beauv.） 叶片保护物质及保护酶的影响

研究了生长在1.875 mmol·L-1和15 mmol·L-1硝态氮素水平条件下的谷子(Setaria italica(L.)Beauv.)开花期间在进行强度为7.12 kJ·m-2.d-1增强UV.B辐射处理时叶片类黄酮含量、苯丙氨酸解氨酶(PAL)和保护酶活性变化差异.主要结果表明在开花期无论是否进行增强UV-B辐射处理,较低水平氮素均比较高水平氮素更有利于提高谷子叶片PAL活性;叶片类黄酮含量除在进行增强UV-B处理时较低氮素条件下生长的谷子在开花末期显著高于较高氮素条件下生长的谷子外,受氮素水平影响不甚明显.而在开花期不进行与进行增强UV-B辐射处理,氮素水平对叶片保护酶的影响有所差异:不进行增强UV-B辐射处理,整个开花期氮素水平对谷子叶片SOD活性有显著影响而对ASP活性无显著影响,对CAT和POD活性则在开花期部分阶段有显著影响.进行增强UV-B辐射处理,整个开花期氮素水平对谷子叶片SOD与CAT活性有显著影响而对ASP、POD活性影响不显著.     

滤减UV-B辐射对烟叶可溶性蛋白、光合色素和类黄酮的影响

在云南玉溪烟区种植烤烟海拔最高(1806.0m)的通海县,通过盆栽烤烟K326试验,研究了在滤减自然的太阳UV-B辐射强度25%、50%和65%条件下,UV-B辐射对烟叶发育过程中可溶性蛋白、光合色素和类黄酮的影响。结果表明:随叶龄增加,可溶性蛋白含量下降,光合色素降解,类黄酮在老叶中积累,蛋白质在生理成熟期对UV-B辐射最敏感。与对照相比,减弱UV-B辐射处理降低了烟叶类黄酮和可溶性蛋白含量,但光合色素含量上升;较低的UV-B辐射降低了叶绿素的降解速度。结果从一侧面说明UV-B辐射对烟叶蛋白质的合成是有益的,类黄酮和叶绿素的变化是对UV-B辐射变化的适应性反应,类黄酮与蛋白质之间可能存在一定的偶联关系。     

滤减UV B辐射对烟叶可溶性蛋白、〖HJ*3〗〖HJ*2〗光合色素和类黄酮的影响

在云南玉溪烟区种植烤烟海拔最高(1806.0m)的通海县,通过盆栽烤烟K326试验,研究了在滤减自然的太阳UV-B辐射强度25%、50%和65%条件下,UV-B辐射对烟叶发育过程中可溶性蛋白、光合色素和类黄酮的影响。结果表明:随叶龄增加,可溶性蛋白含量下降,光合色素降解,类黄酮在老叶中积累,蛋白质在生理成熟期对UV-B辐射最敏感。与对照相比,减弱UV-B辐射处理降低了烟叶类黄酮和可溶性蛋白含量,但光合色素含量上升;较低的UV-B辐射降低了叶绿素的降解速度。结果从一侧面说明UV-B辐射对烟叶蛋白质的合成是有益的,类黄酮和叶绿素的变化是对UV-B辐射变化的适应性反应,类黄酮与蛋白质之间可能存在一定的偶联关系。     

UV-B辐射增强对芦苇光合生理及叶绿体超微结构的影响

在UV-B辐照增强条件下,研究不同辐照梯度对芦苇光合特性、光合色素含量及叶绿体超微结构的影响. 结果表明: 与自然光照相比,UV-B辐照增强显著降低芦苇叶片净光合速率、气孔导度、蒸腾速率,且随辐照强度增大,降低程度加剧,胞间CO₂浓度升高,光合效率显著降低;与自然光照相比,UV-B辐照增强显著降低芦苇叶片光合色素含量(包括叶绿素a、叶绿素b、总叶绿素和类胡萝卜素),且随辐照强度增大,降低程度加剧;UV-B辐射增强条件下,叶绿体超微结构遭到破坏,表现为叶绿体结构变形,类囊体片层排列稀疏紊乱、膨胀甚至模糊不清,并且UV-B辐射强度越大,损伤越大,高强度UV-B辐射对叶绿体超微结构的影响大于低强度辐射.     

田间增加UV-B辐射对玉米光合生理的影响

自然条件下,分别增加0(CK组)、0.01(R1组)和0.015 J.m-2.s-1(R2组)3种强度的UV-B辐射处理玉米(Zea maysL.),对重庆地区C4植物玉米整个生长期内光合作用的影响进行研究。结果表明,增强UV-B辐射导致玉米幼苗叶片光合色素含量(包括叶绿素a、叶绿素b、总叶绿素和类胡萝卜素)、Hill反应活力、气孔导度、光合速率下降,且随UV-B辐射强度的增加,玉米幼苗光合作用所受抑制增强,而玉米成株所受影响不大。     

增强UV-B辐射和氮素互作对植物生长代谢影响的研究进展

不同氮源条件下,UV-B辐射增强能改变植株对氮的吸收利用以及植株叶片的碳氢比和碳氮比,增加氨基酸的生物合成.缺氮条件下, UV-B辐射增强使植物叶片中SOD、POD活性增强,MDA含量增加;氮素过量时,UV-B辐射增强会降低植物对UV-B辐射的耐性.UV-B辐射增强和氮缺乏相互作用会降低叶片的光合速率、叶绿素含量、可溶性糖及淀粉含量,从而抑制植物的生长,降低生物量.该文对近年来国内外有关UV-B辐射增强与氮素相互作用对植物抗氧化系统、氮代谢、光合作用、生物量和形态结构的影响进行综述.     

紫外辐射对菹草成株生理特性的影响

研究不同剂量UV-B辐射下菹草生理特征变化,在光合有效辐射、UV-A辐射一致的条件下,对菹草进行不同剂量UV-B辐射,测定菹草叶片光合色素含量及生理生化指标。结果表明:≤10.8 k J/m2剂量辐射可促进叶绿素及类胡萝卜素含量增加,衰亡阶段起抑制作用,10.8 k J/m2一直起到抑制作用,且随剂量的增加,抑制作用增强;UV-B辐射初期可促进过氧化氢酶(CAT)、过氧化物(POD)酶活性及丙二醛(MDA)含量升高,且随辐射剂量增加而逐渐升高,但随辐射时间延长,CAT、POD酶活性、MDA含量均有所降低,超氧化物歧化酶活性随辐射时间延长逐渐升高,且随辐射剂量增加而增加;短期辐射可促进叶片可溶性蛋白质和可溶性糖的合成,其含量随辐射剂量增加而升高,长期辐射起抑制作用,且随辐射剂量增加,抑制作用增强。因此,春末夏初野外强UV-B辐射可能是促进菹草大批衰亡的重要原因。     

UV-B辐射对雨生红球藻光合特性和虾青素含量的影响及其响应

实验研究了不同强度的UV-B(280-320 nm)辐射对雨生红球藻(Haematococcus pluvialis)的光合活性、生物量、色素含量、活性氧(ROS)含量和抗氧化酶活性等的影响, 以探讨利用UV-B辐射诱导虾青素生物合成增强的可能性。结果发现, 经UV-B辐射处理后,雨生红球藻的光合活性降低、生物量增长被抑制。UV-B辐射对叶绿素影响不大, 但会改变细胞的类胡萝卜素和虾青素含量:0.1和0.3 W/m2强度的UV-B辐射使细胞中的这两种色素含量升高, 0.5 W/m2组的色素含量短暂升高后恢复到对照水平。中低强度的UV-B可以促进雨生红球藻单细胞虾青素含量的增加, 但由于其对细胞生长的抑制作用, 并不能使虾青素大量积累。随辐射时间延长, 细胞内ROS含量未明显增加,但抗氧化酶(过氧化氢酶和超氧化物歧化酶)活性下降, 雨生红球藻可能主要依靠虾青素来淬灭ROS。以上结果表明, UV-B辐射对雨生红球藻的主要生理生化过程有抑制作用, UV-B辐射既可以诱导虾青素的合成又会消耗一部分虾青素, 对虾青素含量的影响与其强度有关, 而利用虾青素来清除细胞内的ROS可能是雨生红球藻抵御这种不利环境条件的最重要的途径。       

祁连圆柏和圆柏色素含量及其花青苷合成酶活性的季节性变化

以祁连圆柏(Sabina przewalskii)和圆柏(S. chinensis)为材料, 测定2种植物花青苷、类黄酮、紫松果黄素、叶绿素和 类胡萝卜素的含量及花青苷合成过程中关键酶苯丙氨酸解氨酶(PAL)和类黄酮糖基转移酶(UFGT)的活性, 并分析了各值的季节性变化。结果表明, 祁连圆柏和圆柏叶片中PAL及UFGT的活性、花青苷、类黄酮﹑紫松果黄素以及类胡萝卜素的含量在低温季节均明显高于其它季节; 叶绿素含量在低温季节低于其它季节; 并且祁连圆柏中花青苷含量及其合成酶PAL和UFGT的活性以及类黄酮、紫松果黄素和叶绿素含量始终高于圆柏。结果说明花青苷是圆柏属植物中具有抗冻特性的重要次生代谢物,是抵御低温和辐射胁迫的一种重要保护物质; 紫松果黄素等色素对圆柏属植物抵抗低温诱导的光抑制起重要作用。     

Responses of the flavonoid pathway to UV-B radiation stress and the correlation with the lipid antioxidant characteristics in the desert plant Caryopteris mongolica

Caryopteris mongolica is a dwarf shrub mainly found in grassland and desert areas of north-west China, and which can survive severe environmental stress. This study aimed to assess the responses of the flavonoid pathway to UV-B radiation treatments and its correlation to the lipid peroxide and antioxidant systems in C. mongolica. In UV-B radiation experiments, plants were exposed to UV-B radiation treatments with a intensity of 30 J/s for 1, 4 and 24 h, respectively. A control group without UV-B radiation treatment was also used. The chlorophyll fluorescence parameters, contents of chlorophyll and carotenoid, levels of lipid peroxidation, activities of antioxidant system enzymes, accumulations of total flavonoids and anthocyanins, and activities of phenylalanine ammonialyase (PAL) and chalcone isomerase (CHI) under different UV-B radiation treatments were investigated. The correlations between products and key enzymes in the flavonoid pathway and the lipid peroxide and antioxidant systems were also analyzed. The results showed that chlorophyll fluorescence parameters decreased within 24 h of treatment. The chlorophyll contents decreased within 4 h and remained stable after 24 h. Carotenoid content significantly increased. The level of MDA, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD) and the contents of total flavonoids and anthocyanidins increased, while catalase (CAT) activity decreased under UV-B stress. The activities of PAL and CHI also increased with the increased content of total flavonoids. The flavonoid products anthocyanidins had a significant positive correlation with MDA level, as well as the activities of antioxidant enzyme SOD. In conclusion, UV-B radiation induced the degradation of photosynthetic pigments and decreased photochemical efficiency of Photosystem II; increased the contents of MDA, total flavonoids and anthocyanidins; and also enhanced activities of antioxidant enzymes (SOD, APX and POD) and key enzymes (PAL and CHI) in the flavonoid pathway in C. mongolica. Thus, we speculate that the flavonoid pathway were involved in the regulation of stress resistance in C. mongolica.     

UV-B辐射对烟草光合色素和几种酶的影响

对UV-B胁迫条件下烟草叶片相关生理生化指标的变化进行研究.结果表明,UV-B辐照后,烟草叶片内光合色素(叶绿素a、叶绿素b、类胡萝卜素)的含量均呈上升趋势,3种色素比对照分别上升了21%、10%、27%;可溶性蛋白含量呈先上升后下降趋势;过氧化物酶活性明显上升,同工酶图谱分析证实,有一种新的过氧化物酶同工酶表达;利用重组噬夏孢欧文氏菌(Erwinia uredovora)GGPP合成酶免疫家兔,制备了兔抗GGPP合成酶的抗血清.Western blot检测显示,UV-B辐照可使烟草叶片GGPP合成酶(GGPS)的表达量显著提高.     

CaCl_2对UV-B辐射下菠菜叶片光合特性的影响

以"丹麦旺盛菠菜"为材料,通过UV-B和CaCl2复合处理,测定光合色素含量、Hill反应活力、叶绿素荧光、MDA含量和抗氧化酶活性等参数,探讨了CaCl2对UV-B辐射下菠菜叶片电子传递链和光合膜酶保护系统的影响。结果表明,UV-B处理下,光合色素含量、chl/car、类囊体膜上PSII潜在活性(Fv/Fo)、光化学淬灭系数(qP)、非光化学淬灭系数(qN)、PSII光量子产量(ΦPSⅡ)、原初光能转化效率(Fv/Fm),以及Hill反应活力等降低,chla/chlb和MDA含量升高;喷洒CaCl2可不同程度缓解UV-B的伤害。不同处理下,POD、SOD和CAT活性的变化呈现补偿效应。UV-B强度与菠菜叶片PSII功能受损程度呈正相关,CaCl2则主要通过提高chlb含量、类囊体膜上的光量子产量和POD活性,以缓解伤害。重度UV-B辐射下,CaCl2使chlb含量显著提高可能是导致PSII捕光效率提高的重要因素。     

Effects of an enhanced ultraviolet-B irradiation on photosynthetic apparatus of several forest coniferous tree species from different locations

The effect of UV-B on the photosynthetic apparatus of coniferous trees: Picea abies (L.) Karst., Picea pungens (Engelm.), Pinus sylvestris (L.), Pinus cembra (L.) and Abies alba (Mill.) was investigated. Three and four-year-old plantlets coming from different latitudes, longitudes and altitudes were used. The experiment was carried out in greenhouse. Two doses of ultraviolet-B irradiation were applied: control=0, low dose=11.32 and high dose=22.64 kJ·m⁻²·d⁻¹ UV-B_BE (biologically effective irradiance of UV-B). Measurements of chlorophyll fluorescence, gas exchange, chlorophyll and flavonoids content were carried out. Response of forest trees to an increased UV-B radiation depends on species, location of place of pantalets collecting and UV-B dose. Pinus cembra, Picea abies and Pinus sylvestris from high altitude (1000 m a.s.l.) were less sensitive to UV-B than these from plain location. The altitude determined adaptation of forest coniferous trees to an enhanced UV-B radiation much more than the latitudinal gradient. Permanent discoloration was observed only on the young needles of the fir plantlets that were grown in light limiting conditions. Photosynthetic parameters were affected by the UV-B radiation. Both maximal and the steady state fluorescence of chlorophyll were reduced as a consequence of elevated UV-B in case of some species. The chlorophyll content was enhanced, increased or was not affected according to species and to locations. The flavonoids content in the needles increased with chlorophyll content at both UV-B treatments. An opposite trend was found in the control. The increased content of screening pigments in the needles of all the tested coniferous trees was detected. Picea abies and Picea pungens photosynthesis response curves to the light and to the intercellular CO₂ concentration did not change significantly under increased UV-B because of higher concentration in screening pigments in leaves. The increased concentration of flavonoids in forest litter may lead to changes in the biogeochemical cycle in the forest ecosystem.     

Changes in Pigment Composition and Photosynthetic Activity of Aquatic Fern (Azolla Microphylla Kaulf.) Exposed to Low Doses of UV-C (254 nm) Radiation

Changes in the content of pigments and rate of photosynthesis in Azolla microphylla Kaulf. fronds were measured during growth under solar and ultraviolet-C (UV-C) supplemented solar radiation. Maximum content of total chlorophyll (Chl) was observed on the 13^th day (termination of the experiment) of treatment in both control and treated plants. The treated plants had significantly lower total Chl and carotenoid contents than the control plants during the 1^st day of growth. After the 4^th day of exposure to UV-C supplemented solar radiation, the Chl and carotenoids accumulation increased in treated plants, so that the pigment concentration in the treated fronds was nearer to the control values after the 13^th day of treatment. Significant increase in UV absorbing pigments, anthocyanins, and flavonoids was observed at the 13^th day of treatment. In spite of the roughly similar photosynthetic pigment concentration, the photosynthetic activity measured as the rate of electron transport at photosystem 2 was only 65 % of the control values after 13 d of UV-C exposure. This revised version was published online in June 2006 with corrections to the Cover Date.     

Changes in morphological, photosynthetic and physiological responses of Mono Maple seedlings to enhanced UV-B and to nitrogen addition

In the southeast of the Qinghai-Tibetan Plateau of China, Mono Maple is a common species in reforestation processes. The paper mainly investigated the changes in morphological, photosynthetic and physiological responses of Mono Maple seedlings to UV-B radiation, nitrogen supply and their combination. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m⁻² day⁻¹; enhanced UV-B, 14.33 KJ m⁻² day⁻¹) and two nitrogen levels (0; 20 g N m⁻² a⁻¹)—to determine whether the adverse effects of UV-B on plants are eased by nitrogen supply. Enhanced UV-B caused a marked decline in growth parameters, net photosynthetic rate, and photosynthetic pigments, whereas it induced an increase in reaction oxygen species (hydrogen peroxide accumulation and the rate of superoxide radical production) and malondialdehyde content. Enhance UV-B also induced an increase in antioxidant compounds of Mono Maple, such as UV-B absorbing compounds, proline content, and activities of antioxidant enzymes (peroxidase, superoxide dimutase and catalase). On the other hand, nitrogen supply caused an increase in some growth parameters, net photosynthetic rate, photosynthetic pigments and antioxidant compounds (peroxidase, proline content and UV-B absorbing compounds), and reduced the content of reaction oxygen species (H₂O₂ accumulation, the rate of O₂⁻ production) and malondialdehyde content under ambient UV-B. However, under enhanced UV-B, nitrogen supply inhibited some growth parameters, and increased H₂O₂ accumulation, the rate of O₂⁻ production and MDA content, though proline content, UV-B absorbing compounds and activities of POD and SOD increased. These results implied that enhanced UV-B brought harmful effects on Mono Maple seedlings and nitrogen supply made plants more sensitive to enhanced UV-B, though increased some antioxidant activity.     

长期增强UV-B辐射对高寒草甸植物光合速率和抗氧化系统的影响

研究了在野外自然条件下,长期增强UV-B辐射对高寒草甸3种典型植物矮嵩草（Kobresia humilis）、垂穗披碱草（Elymus nutans）和钉柱委陵菜（Potentilla saundersiana）光合放氧速率、光合色素和抗氧化系统的影响。结果表明：长期增强UV-B辐射对3种植物的净光合速率没有明显影响。增强UV-B辐射下,3种植物的叶绿素含量变化不同,Chla／b值,类胡萝卜素（Car）含量,Car／Chl值与对照相比都有升高,说明植物叶片的光合能力、吸收紫外线的能力增强以及忍受逆境能力均有增强,从而产生光保护,有利于光合作用正常进行。由于3种植物膜脂过氧化程度的不同及SOD活性的普遍抑制,植物经受了氧化胁迫。垂穗披碱草叶片GSH含量显著七升,矮嵩草的形态矮小及钉柱委陵菜GSH含量与POD活性显著上升,都能减轻它们所经受的氧化胁迫,使光合器官免受损伤。所以,这些保护性色素的积累和抗氧化系统内部的协同作用可能是高寒草甸植物光合作用正常进行的重要原因。     

Leaf expansion and development of PHOTOSYNTHETIC CAPACITY AND PIGMENTS IN Liquidambar styraciflua (Hamamelidaceae)—EFFECTS OF UV-B RADIATION

In order to perform their functions as photosynthetic organs, leaves must cope with excess heat and potentially damaging ultraviolet radiation. Possible increases in the UV-B portion of the solar spectrum may place an additional burden on leaves, and this could be particularly important for young expanding leaves with poorly developed UV-B defense mechanisms. We evaluated the effects of supplemental UV-B radiation on leaf expansion and the development of photosynthetic capacity and pigments in sweetgum (Liquidambar styraciflua L.) seedlings. Seedlings were grown in the field under either ambient or ambient plus 3 or 5.0 kJ of biologically effective supplemental UV-B radiation. Although final leaf size was unaffected, the rate of leaf elongation and accumulation of leaf area was slower in leaves exposed to the lower supplemental UV-B irradiance. In contrast, chlorophyll accumulation and the development of photosynthetic capacity was more rapid in plants exposed to the higher, compared to the lower supplemental UV-B irradiance. The accumulation of anthocyanins and other putative flavonoids or UV-absorbing compounds was scarcely affected by exposure to supplemental UV-B radiation. These results suggest that the UV-B portion of the solar spectrum may, in the absence of gross affects on biomass, exert subtle influences on leaf ontogeny and the development of photosynthetic pigments and capacity in sweetgum.