植物对UV-B辐射的响应与调控机制

UV-B(ultraviolet-B)辐射会在多个方面对植物产生影响,随着研究的不断深入,人们发现UV-B除了作为一个胁迫因子外,还会作为信号调节因子来调节植物的生长发育.本文把UV-B辐射对植物形态建成和生理代谢的影响、植物响应UV-B辐射的信号通路以及UV-B与其他因子复合作用对植物的影响等进行了论述,并对植物响应UV-B辐射的研究做了展望.     

UV-B辐射增强对植物影响的研究进展

UV-B辐射的增强对植物的影响是目前科学研究的热点之一。本文综述了国内外有关UV-B辐射增强对植物影响的研究现状与动态,讨论了在增强了UV-B辐射时,植物在生长发育、生理形态、光合作用、物质次生代谢、抗氧化系统和分子防御反应等多个层次的变化,同时还探讨了UV-B辐射与其它环境因素联合作用对植物的影响。并展望了UV-B辐射对植物的影响领域中值得深入探讨的问题。     

紫外辐射增强对植物糖代谢的影响

综述了UV-B辐射增强对植物叶片、茎、根、果实以及籽粒中糖含量影响的研究现状与动态,从生理学角度分析了UV-B辐射对植物糖含量和糖代谢相关的一些重要反应及其影响植物糖含量和糖代谢的关键酶的响应,并从植物的光合碳固定、糖的合成与分解等方面阐述了UV-B影响糖含量及糖代谢的可能机理。展望了今后紫外辐射增强对植物糖代谢影响的研究重点和研究方向。     

植物酶系统对UV-B辐射的响应机制

紫外辐射作为一种自然界存在的环境因子,影响着植物的生长发育。在植物从太阳辐射中获得光照和热量的同时,不可避免地要受到UV-B辐射的胁迫。植物在长期对环境的适应中,在体内形成了防御系统,以保护自身的安全,酶系统是其中之一。植物酶系统在实施防护的同时也受到了UV-B辐射的影响,信号分子对调节酶响应UV-B胁迫起了关键作用。本文重点论述了UV-B辐射增强下,植物酶系统的变化、植物酶系统的响应机制以及酶系统与信号物质的关系,并对该领域未来的研究方向提出了展望。     

UV-B辐射方向对白三叶克隆整合的影响

增强UV-B辐射会对植物生长和生理生化过程产生有害效应。克隆植物中,相连的克隆分株对经常共享资源和激素,然而鲜有关于异质性UV-B辐射下UV-B辐射方向对克隆整合的影响及克隆植物形态结构变化的报道。模拟同质(克隆分株片段均处于自然背景辐射)和异质(克隆分株一端处于自然背景辐射,另一端处于补加的UV-B辐射)UV-B辐射,以克隆植物白三叶为材料,进行连接和隔断处理,研究UV-B辐射方向对克隆整合强度变化、叶片形态结构特化及生理可塑性的影响。结果表明:异质性UV-B辐射下,15N同位素标记端保留的15N百分比高于同质UV-B辐射处理,转移到无标记相连端的15N含量则降低,紫外辐射处理和同位素标记是否处于同一分株端对结果无显著性影响,说明克隆植物白三叶生理整合存在但整合强度降低,辐射方向与克隆整合强度无关;隔断处理组气孔长度增加,栅栏组织增厚,但连接处理组却无此变化,表明生理整合在白三叶叶片形态结构特化中发挥作用。UV-B辐射下,最小荧光、电子传递速率及光化学淬灭系数降低但非光化学淬灭系数升高,而生理整合却使结果相反;叶绿素和紫外吸收物可在异质性UV-B辐射相连的两端运输分享。以上均表明异质UV-B辐射环境中,UV-B辐射胁迫端克隆分株通过生理整合从非胁迫端获益,并以此提高胁迫环境中克隆植物对资源的利用效率。     

克隆整合提高异质性UV-B辐射下活血丹抗氧化酶活力

增强UV-B辐射会对植物生长和生理生化过程产生有害效应。克隆植物中,相连的克隆分株对经常共享资源和激素,然而鲜有关于异质性UV-B辐射下抗氧化酶活力变化的报道。本研究模拟同质(克隆分株片段均处于自然背景辐射)和异质(克隆分株一端处于自然背景辐射,另一端处于补加的UV-B辐射)UV-B辐射,以克隆植物活血丹为材料,进行连接和隔断处理,研究异质性UV-B辐射下,克隆整合对活血丹抗氧化酶(超氧化物歧化酶(SOD),过氧化物酶(POD)和过氧化氢酶(CAT))活力的影响。结果表明:与处于同质UV-B辐射环境相比,异质UV-B辐射下连接处理中的活血丹UV-B辐射端抗氧化酶活力显著增加,说明克隆植物生理整合存在,且克隆整合提高了活血丹抗氧化酶活力。表明异质UV-B辐射环境中,UV-B辐射胁迫端克隆分株通过生理整合从非胁迫端获益,最大化地利用资源。     

异质性UV-B辐射下NO在活血丹光合特性中的作用研究

我们前期研究发现异质性UV-B辐射下NO参与克隆植物紫外吸收物和抗氧化酶活力的整合过程。光合作用在植物生长过程中十分重要,但异质性UV-B辐射下NO在克隆植物光合特性中是否发挥作用仍不清楚。本研究模拟同质(克隆分株片段均处于自然背景辐射)和异质(克隆分株一端处于自然背景辐射,另一端处于补加的UV-B辐射)UV-B辐射,以克隆植物活血丹为材料,研究异质性UV-B辐射下,NO清除剂在克隆整合提高活血丹气体交换参数和叶绿素含量中的作用。结果表明:与处于同质UV-B辐射环境相比,异质UV-B辐射下连接处理中的活血丹UV-B辐射端气体交换参数和叶绿素含量显著增加,但NO清除剂改变了这一趋势,说明NO作为信号分子在克隆植物生理整合提高了活血丹光合生理特性中发挥重要作用,有助于全面认识UV-B辐射在克隆植物生长调控中的作用,为了解异质性UV-B环境下克隆植物生理整合的机理提供理论依据。     

陆生植物体内酶系统对UV-B辐射增强的响应

臭氧层减薄导致地表中波紫外线UV-B(280～320 nm)辐射的增强,UV-B辐射能量远高于可见光,且能被植物体内蛋白质和核酸等生物大分子吸收.酶是植物体内起催化作用的一类蛋白质,酶的数量和活性对UV-B辐射增强有强烈的响应.本文将近年来增强UV-B辐射对植物体内酶影响的研究工作进行了综述.主要包括抗氧化酶、核酮糖-1,5-二磷酸羧化酶、硝酸还原酶和谷氨酰胺合成酶.并就今后该方面的研究提出建议.     

UV-B辐射胁迫下不同起源时期的3种木本植物幼苗的生长及光合特性

平流层臭氧的减薄导致到达地表UV-B辐射增强是全球所面临的环境问题之一。UV-B辐射胁迫对植物的生物学效应研究成为继全球大气二氧化碳浓度升高对植物影响研究之后的又一热点领域。设置了UV-B滤光减弱组、UV-B辐射增强组和自然光对照组3组大田实验,选择不同起源时期的乐东拟单性木兰(Parakmeria lotungensi)、青冈(Cyclobalanopsis glauca)、山核桃(Carya cathayensis)幼苗为实验材料,测定每组中3种植物的生长量与光合特征参数,通过对比组间和种间差异,研究不同起源时期的3种木本植物对UV-B辐射胁迫的响应模式,分析3种植物对于UV-B辐射胁迫的适应性与自身起源和进化时间的关系,为"起源时间越早的木本植物生长发育和光合生理能否更好地适应UV-B辐射胁迫"这一科学命题的探讨提供一定实验参考。得到如下结果:(1)相对于自然光照条件,增强UV-B辐射胁迫对3种木本植物的地径和株高都有抑制作用;对乐东拟单性木兰、青冈的Pn和Amax有一定的抑制作用,对山核桃Pn和Amax则具有一定的促进作用。减弱UV-B辐射胁迫对3种木本植物的地径起到抑制作用,对乐东拟单性木兰、青冈幼苗的株高生长有促进作用,但对山核桃的株高却具有抑制作用;对乐东拟单性木兰以及山核桃的Pn和Amax有一定的抑制作用,而对青冈Pn和Amax则有促进作用。(2)对比种间差异,发现3种不同的UV-B光照条件下青冈的地径生长量都最大,乐东拟单性木兰次之,山核桃最小;株高生长量种间大小排序不一致;相对于自然光照条件,增强UV-B辐射强度下山核桃Pn、Amax的比值都最大,青冈次之,乐东拟单性木兰最小;减弱UV-B辐射强度下青冈的Pn、Amax的比值都最大,乐东拟单性木兰次之,山核桃最小;表明不同起源时间对植物抗UV-B辐射胁迫能力有一定的影响,但不是决定性因素。UV-B辐射增强和过滤减弱胁迫对3个树种幼苗的生长发育、光合作用、叶绿素均有影响,但不同起源时期3种木本植物幼苗光合特征参数的响应模式不一,其机制尚待进一步开展实验进行求证。本研究结果可丰富和补充UV-B辐射胁迫对木本植物的影响研究,为从进化角度筛选UV-B胁迫抗性较强的植物提供了一定的依据。     

拟南芥黏连蛋白RAD21对增强UV-B辐射后细胞分裂的响应

UV-B辐射对植物的影响体现在多个水平,其会引起植物DNA损伤,造成有丝分裂异常,最终影响植物的生长发育及生理生化过程。RAD21.3是黏连蛋白复合物的一个亚基,参与有丝分裂中染色体的分离。该研究以哥伦比亚生态型拟南芥(Arabidopsis thaliana)和atrad21.3突变体为材料,设置对照(CK)及UV-B处理组,对野生型(WT)、atrad21.3及过表达株系的根长、株高、抽薹时间和生理生化指标进行统计分析。利用碱性品红染色观察拟南芥根尖的有丝分裂现象,并统计畸变率。SPSS分析结果表明, UV-B处理后, WT UV-B和atrad21.3 CK的抽薹时间、株高及各项生理生化指标与WT CK相比无显著差异,但atrad21.3UV-B与之相比差异显著。通过烟草(Nicotianabenthamiana)的瞬时表达和亚细胞定位观察,发现RAD21.3集中在细胞核;进一步观察分裂期细胞发现落后染色体、染色体桥和游离染色体等异常现象。统计结果表明,与WT CK相比, WT UV-B和atrad21.3 CK的畸变率较高,但atrad21.3 UV-B的畸变率更高,表明RAD21.3可能响应UV-B辐射诱导的异常有丝分裂。     

UV-B辐射对拟南芥细胞周期G1/S期转变的影响

以同步化的拟南芥(Arabidopsis thaliana)根尖细胞为材料, 研究了UV-B辐射对拟南芥细胞周期G1/S期转变的影响。细胞周期荧光显微图像分析表明, UV-B辐射延缓了拟南芥根尖细胞G1/S期的转变。基因表达的RT-PCR检测表明, 在UV-B辐射下G1/S期转变的标志基因Histone H4和E2Fa的表达受抑制, 而G1/S期转变的抑制因子KRP2基因表达则受诱导上调。单细胞凝胶电泳检测结果表明, UV-B辐射引起拟南芥根尖细胞内积累大量的环丁烷嘧啶二聚体。以上结果表明, UV-B辐射抑制植物的生长可能受细胞周期和DNA损伤调控。     

UV-B辐射对拟南芥细胞周期G1/S期转变的影响

以同步化的拟南芥（Arabidopsis thaliana）根尖细胞为材料,研究了UV-B辐射对拟南芥细胞周期G1／S期转变的影响。细胞周期荧光显微图像分析表明,UV-B辐射延缓了拟南芥根尖细胞G1／S期的转变。基因表达的RT-PCR检测表明,在UV-B辐射下G1／S期转变的标志基因HistoneH4和E2Fa的表达受抑制,而G1／S期转变的抑制因子KRP2基因表达则受诱导上调。单细胞凝胶电泳检测结果表明,UV-B辐射引起拟南芥根尖细胞内积累大量的环丁烷嘧啶二聚体。以上结果表明,UV-B辐射抑制植物的生长可能受细胞周期和DNA损伤调控。     

UV-B辐射增强对陆地植物次生代谢的影响

平流层臭氧的减薄已导致地表中波紫外辐射(UV-B,280～320nm)增强,由于UV-B能被许多生物大分子如蛋白质和核酸吸收并引起分子构象的变化,因此可对植物的各方面产生影响。本文将近年来特别是近5年的UV-B辐射增强对植物次生代谢物影响的研究工作进行了综述。主要包括：UV-B辐射增强对植物紫外吸收物的影响和可能的机制;环境因子的复合作用对植物紫外吸收物的影响和可能的机制;UV-B辐射增强对次生代谢物影响的生态学意义。并对该领域未来的研究作了展望。     

Effects of ultraviolet-B radiation on the growth and yield of crop plants

This paper reviews growth chamber, greenhouse, and field studies on the effects of ultraviolet-B (UV-B. between 280 and 320 nm) radiation on agricultural crop plants. Our understanding of the physiological effects of UV-B radiation comes primarily from growth chamber studies, where UV-B is artificially supplied via filtered lamps. Both photosystems I and II, as well as carboxylating enzymes, are sensitive to UV-B radiation. Ultraviolet-B radiation also affects stomatal resistance, chlorophyll concentration, soluble leaf proteins, lipids, and carbohydrate pools. In general, the effects of UV-B radiation are accentuated by the low levels of visible radiation typically found inside growth chambers. Ultraviolet-B radiation has also been shown to affect anatomical and morphological plant characteristics. Commonly observed UV-B induced changes include plant stunting, reductions in leaf area and total biomass, and alterations in the pattern of biomass partitioning into various plant organs. In sensitive plants, evidence of cell and tissue damage often appears on the upper leaf epidermis as bronzing, glazing, and chlorosis. Epidermal transmission in the UV region decreases in irradiated leaves. This decrease is primarily associated with a stimulation in flavonoid biosynthesis and is thought to be a protective, screening response to the deleterious effects of UV-B. A considerable degree of variability exists in sensitivity to UV-B radiation between different species. Approximately 30% of the species tested were resistant, another 20% were extremely sensitive, and the remainder were of intermediate sensitivity, in terms of reductions in total dry weight. In addition to this sizable interspecific variability, there appears to be a similarly wide intraspecific variability in UV-B response. The effects of UV-B radiation on crop yield have only been examined in a limited number of field studies, with ambient levels of UV-B radiation being supplemented with fluorescent sun lamps. Due to various deficiencies, all these field experiments to date have only limited utility for assessing the potential impact of enhanced levels of UV-B on crop productivity.     

Effects of UV-B radiation on seed yield of Glycine max and an assessment of F1 generation progeny for carryover effects

Glycine max (L.) Merr plants were grown outdoors in potted sand exposed to elevated ultraviolet-B (UV-B) radiation provided by filtered fluorescent lamps to determine the effects of UV-B on seed yield and UV-B-induced carryover effects in the F1 generation. Increased UV-B radiation had no detectable effects on reproductive parameters except for a reduction on seed number per plant and an increase in the number of unseeded pods per plant and dry weight of unseeded pods per plant in the field supplemental UV-B experiment. Studies on carryover effects in the greenhouse progeny growth trial also showed no effect of parental treatment with UV-B on biomass production, and most symbiotic-N traits and plant metabolite measured. However, the concentrations of N in nodules and starch in roots were significantly increased in the F1 generation progeny from elevated UV-B radiation relative to their F1 counterparts from ambient radiation. Assessing the effects of seed size on plant growth and symbiotic function in the F1 progeny showed that total biomass, dry matter yield of individual organs (leaves, stems, roots and nodules), total plant N and fixed-N rose with increasing seed size. Seed concentration of flavonoids was also enhanced with increasing seed size. These findings suggest that subtle changes did occur in the F1 generation progeny of parental plants exposed to elevated UV-B with potential to accumulate with further exposure to elevated UV-B radiation.     

VARIATION IN UV-B SENSITIVITY IN PLANTS FROM A 3,000-m ELEVATIONAL GRADIENT IN HAWAII

Interest in the potential consequences of stratospheric ozone depletion has led to numerous studies that have evaluated the effects of ultraviolet-B (UV-B) radiation on plant growth and productivity. However, few studies have been conducted on plants from natural ecosystems. Differences in solar UV-B radiation along latitudinal or elevational gradients may have resulted in plants from diverse habitats developing contrasting sensitivities to UV-B radiation. In this study, seeds were collected along a 3,000-m elevational gradient in Hawaii and then germinated and grown in an unshaded greenhouse with either no UV-B radiation or one of two daily UV-B irradiances, 15.5 or 23.1 kj m². Seedlings were grown for 12 weeks and harvested to determine whether UV-B radiation altered plant biomass. The responses to UV-B radiation varied among species, but, in general, sensitivity to UV-B radiation was reduced as the elevation of seed collection increased. Of the 33 species tested, UV-B radiation significantly reduced plant height in 14 species and biomass in eight species. Biomass increased in four species grown under UV-B radiation. This study provides clear evidence that natural plant populations exhibit wide variation in UV-B radiation sensitivity and that this variation is related to the natural (ambient) UV-B radiation environment in which these plants grow.     

UV-B辐射对马尾松凋落叶分解和养分释放的影响

由大气臭氧层减薄导致的UV-B辐射变化将直接影响到凋落物的分解。目前,有关UV-B辐射影响木本植物凋落物分解的研究还很少,在国内还没有开展。采用分解袋法开展了马尾松凋落叶在自然环境和UV-B辐射滤减两种辐射环境下的分解试验。结果表明：在UV-B辐射滤减环境下的马尾松凋落叶年分解速率比对照环境减慢了47.74%。UV-B辐射极显著(p<0.01)地加快了马尾松凋落叶的分解速率,促进了凋落叶中碳、磷、钾的释放和木质素的降解,对氮的释放无明显影响。研究结果意味着UV-B辐射将加快马尾松林的营养循环速度,降低马尾松林凋落物层的碳储量。     

Cadmium Telluride Quantum Dots (CdTe-QDs) and Enhanced Ultraviolet-B (UV-B) Radiation Trigger Antioxidant Enzyme Metabolism and Programmed Cell Death in Wheat Seedlings

Nanoparticles (NPs) are becoming increasingly widespread in the environment. Free cadmium ions released from commonly used NPs under ultraviolet-B (UV-B) radiation are potentially toxic to living organisms. With increasing levels of UV-B radiation at the Earth’s surface due to the depletion of the ozone layer, the potential additive effect of NPs and UV-B radiation on plants is of concern. In this study, we investigated the synergistic effect of CdTe quantum dots (CdTe-QDs), a common form of NP, and UV-B radiation on wheat seedlings. Graded doses of CdTe-QDs and UV-B radiation were tested, either alone or in combination, based on physical characteristics of 5-day-old seedlings. Treatments of wheat seedlings with either CdTe-QDs (200 mg/L) or UV-B radiation (10 KJ/m²/d) induced the activation of wheat antioxidant enzymes. CdTe-QDs accumulation in plant root cells resulted in programmed cell death as detected by DNA laddering. CdTe-QDs and UV-B radiation inhibited root and shoot growth, respectively. Additive inhibitory effects were observed in the combined treatment group. This research described the effects of UV-B and CdTe-QDs on plant growth. Furthermore, the finding that CdTe-QDs accumulate during the life cycle of plants highlights the need for sustained assessments of these interactions.     

增强UV-B辐射及氮水平对长春花生长和生理代谢的影响

地表UV-B 辐射增强和氮沉降增加目前已成为影响植物生长的重要生态因子。本文以药用植物长春花（Catharanthus roseus）为材料,研究UV-B辐射和氮供应增加对长春花生长、生理及长春碱含量的协同效应。研究结果表明,紫外辐射增加对长春花生长和生物量积累具有显著的抑制作用。同时外源增加氮供应能明显缓解紫外辐射引起的生长抑制效应。紫外辐射引起的叶片膜脂过氧化胁迫导致了长春花叶片丙二醛含量显著增加,但同时增加氮供应能显著降低丙二醛水平。增强UV-B辐射处理显著促进长春花叶片UV-B吸收化合物合成积累,并随氮供应增加其含量进一步增加;氮供应增加和UV-B辐射增强共同作用时,长春花叶片中长春碱的含量较其单独作用时均显著增加。上述结果表明,增加氮供应不但可以缓解紫外辐射引起的生长抑制和生理伤害,同时对长春花叶片中生物碱的合成积累具有协同促进效应,其原因可能是增强UV-B辐射能促使长春花利用更多的氮源合成积累长春碱。