UV-B辐射对植物类黄酮影响的研究进展

UV-B辐射增强对农业生态系统和作物产量的影响已引起国内外广泛关注。本文结合近年来国内外研究成果,介绍了UV-B辐射胁迫下植物应激合成与累积类黄酮的特征,考察了类黄酮在抵御UV-B辐射胁迫中的生态生理作用及其机理,探讨了类黄酮与其他抗UV-B辐射机制的关系,分析了未来该研究工作的若干取向。     

UV-B辐射的增强对作物形态及生理功能的影响

通过综述UV-B辐射增强对作物产生的影响,为进一步揭示作物对UV-B辐射增强的响应机制、适应变化和寻找相应的解决方法提供参考.分析发现UV-B辐射增强能对作物的形态在根、茎、叶营养器官和生殖器官方面产生负面影响,从而进一步影响作物的生物量和产量;UV-B辐射增强对植物生理的影响主要通过影响作物的叶绿体、光合作用及矿质代谢而起作用,并且这些影响具有品种间和生育期的差异.因此研究紫外辐射对作物的影响具有重要的生态学意义.     

UV-B辐射增强对水稻蛋白质及核酸的影响研究

盆栽试验研究UV B辐射增强对水稻蛋白质及核酸的影响结果表明 ,UV B辐射增强抑制水稻生长 ,降低水稻生物量和水稻叶片可溶性蛋白质及核酸含量。随UV B辐射的增强 ,水稻叶片蛋白水解酶和核糖核酸酶活性上升 ,硝酸还原酶活性下降 ,叶片总游离氨基酸含量增加。     

UV-B辐射增强对土壤有机碳稳定性的影响

以母质相同、有机碳含量不同的2个水稻土为研究材料,通过室内模拟光照,探讨紫外辐射(UV-B,280~315nm)对土壤总碳(TC)、可溶性有机碳(DOC)和复合酚(AEP)含量的影响以及土层厚度不同(0.95,1.89,2.84mm)对UV-B辐射的响应特征。结果表明:与黑暗处理相比,培养96h后,无论是在有机碳含量低的土壤(A土)还是在有机碳含量高的土壤(B土)中,UV-B辐射均显著降低了土壤TC的含量,却增加了土壤DOC的含量,在试验结束时,土壤A和B的TC含量分别降低了3.11%和6.18%,而土壤DOC含量分别增加了16.05%和9.89%。在UV-B辐射96h后,与1.89,2.84mm土层相比,土层厚度为0.95mm时土壤TC、DOC和AEP含量变化幅度最大,A和B两个土壤中TC含量分别降低了19.11%和14.35%,DOC和AEP含量分别增加了18.66%和18.92%与23.52%和22.70%,而UV-B辐射对厚度为1.89mm和2.84mm的土层TC、DOC和AEP含量并无显著影响。研究结果表明UV-B辐射对土壤碳库稳定性有一定的影响,在农业生产中为了保护碳库稳定性,应该尽量减少地表裸露。     

UV-B辐射增强对水稻多胺含量及其相关酶活性的影响

试验研究表明,处理前期(7～14d)UV-B辐射增强使“汕优63”水稻精氨酸脱羧酶(ADC)、鸟氨酸脱羧酶(ODC)和S-腺苷蛋氨酸脱羧酶(SAMDC)活性分别增加165.74％、104.60％和89.60％,“南川”(NC)运3种酶活性分别增加59.91％、41.30％和23.68％,新品系“IR_(65600-85)”在UV-B辐射胁迫下多胺脱羧酶活性表现与前2品种略不同,即ADC和ODC活性分别提高115.93％、14.45％,而SAMDC活性下降33.01％。处理后期(21～28d)随UV-B辐射累积量的增加,这3种酶活性均有所下降,其中ODC和SAMDC活性降幅大于ADC,其中“汕优63”ADC、和ODC活性分别比对照增加89.72％、3.71％,“南川”则分别增加73.95％、27.38％,“IR_(65600-85)”ADC活性增加94.41％,ODC、活性却下降13.57％。处理后期(21～28d)3类水稻“汕优63”、“南川”和“IR_(65600-85)”SAMDC分别下降40.06％、19.20％和38.21％。多胺氧化酶(PAO)活性变化趋势则相反,即处理前期(7～14d)呈不同程度下降趋势,处理后期(21～28d)则呈极显著上升趋势,其结果引起多胺(PA)含量特别是腐胺(Put)含量明显上升。水稻对UV-B辐射增强的反应具有基因型差异。     

镧对UV-B辐射胁迫下大豆幼苗叶绿素含量的影响

采用水培实验方法研究了La对紫外辐射（UV—B2 0．15WM^-2,0．45Wm^-2）胁迫下大豆（Glycine max）幼苗叶绿素含量及叶绿素a／b值的影响。实验结果表明：与CK相比，无UV—B胁迫时20mgL^-1LaCl3能明显提高大豆幼苗的叶绿素含量，且叶绿素a的增幅（12．77％）大于叶绿素b（0．00）；UV—B处理使大豆幼苗叶绿素含量降低，且T2处理（0．45Wm^-2）中的下降幅度（12．18％）大于T1（0．15Wm^-2）处理，叶绿素a的降幅大于叶绿素b。但适量浓度的La溶液有抑制叶绿素含量降低的作用；在叶绿素含量变化动态图中，20mgL^-1LaCl2处理组叶绿素含量均高于CK组，也高于60mgL^-1LaCl3处理组，La＋UV—B处理组叶绿素含量与UV-B处理组走势近似。但降幅小于后者，即La具有提高大豆幼苗叶绿素含量、缓解UV—B辐射伤害的作用。     

UV-B辐射增强对葡萄光合作用日变化的影响(简报)

大气臭氧层的不断破坏引起了地球表面紫外线-B(UV-B）辐射强度不断增加,这对植物的生长发育产生了重要影响。试验以酿酒葡萄（V.vinifera. L）“赤霞珠”（Cabernet Sauvignon）为材料,在自然光照条件下,通过增加不同强度的UV-B辐射,研究UV-B辐射增强对葡萄叶片光合作用日变化的影响,为进一步研究UV-B辐射增强对植物的影响提供依据。结果表明,UV-B辐射增强后葡萄叶片净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）、蒸腾速率（Tr）均呈双峰型,且日变化平均值表现为低辐射（T₁,10.8 μW/cm²）处理组＞对照组（CK）＞高辐射（T₂,25.6 μW/cm²）处理组,而水分利用效率则表现为对照组（CK）＞低辐射（T₁,10.8 μW/cm2）处理组＞高辐射（T₂,25.6 μW/cm2）处理的变化趋势。同时,UV-B辐射增强对葡萄叶片中光合色素含量没有显著的影响。这说明UV-B辐射增强对葡萄光合作用的影响与UV-B辐射强度和照射时间有关,适当增加一定剂量的UV-B辐射对葡萄光合作用不会造成危害。     

氮对UV-B辐射增强条件下大麦孕穗期叶片生理特性的影响

通过大田试验,研究在UV-B辐射增强条件下,不同施氮量对大麦孕穗期叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、叶片水分利用效率(WUE)及胞间CO2浓度(Ci)日变化的影响。UV-B辐射设两个水平,即对照(CK,自然光,辐射强度1.5kJ.m-2.h-1)和增强20%(1.8kJ.m-2.h-1);施氮量设两个水平,即低氮和高氮(30kg.hm-2和150kg.hm-2)。结果表明,UV-B辐射增强下,高氮处理的Pn、Tr、Gs和WUE的日平均值比对照分别下降了44.6%、21.8%、17.8%和28.4%;低氮处理分别下降了49.5%、11.8%、12.9%和42.7%,说明UV-B辐射增强可降低大麦叶片的光合作用和水分利用效率,而增施氮肥可缓解UV-B辐射增强对光合作用的影响,并缓解UV-B辐射增强对大麦净光合速率的抑制,但是并不能缓解UV-B辐射增强对蒸腾速率及气孔导度的抑制。Ci及Pn的日变化趋势表明,UV-B辐射增强及氮肥对大麦叶片光合作用的影响不是通过气孔,而是通过对光合作用反应过程的直接影响来实现的。     

UV-B辐射增强对大麦生理生态的影响

在大田条件下,研究了UV-B辐射增强对大麦的生长发育、光合作用、蒸腾作用及其产量构成的影响。结果表明,UV-B辐射增强明显抑制大麦生长,使株高变矮、绿叶数减少、叶面积和干物质量下降,但抑制程度随生育期而异。在UV-B辐射增强条件下,大麦叶片叶绿素含量、净光合速率、气孔导度和蒸腾速率都有不同程度的降低,水分利用率也随之降低。UV-B辐射增强对大麦形态学和生理学上的不利影响,导致了大麦产量下降24.96%。     

地表臭氧含量增加和UV-B辐射增强对大豆生物量和产量的影响

利用开顶式气室(OTC)设置4个处理对大豆进行O3与UV-B增强的大田试验,通过观测生物量和产量研究两者对大豆生长的影响。T1为O3含量100nmol/mol的处理,T2为UV-B辐射强度比CK增加10%的处理,T3为T1和T2的复合处理,CK为自然空气。结果表明,O3含量与UV-B辐射增强的单因素对大豆株高、叶面积、茎干重等生物量都有不同程度的负影响,而两者复合后对各生物量的影响效果不一致,在分枝期至结荚期拮抗作用居多,而协同作用则多出现在生育期末期。在整个生育期,各处理均表现为茎分配指数变化幅度较小,CK、T1、T2、T3的根和叶分配指数逐渐降低,且荚分配指数呈快速上升的趋势。由此可见,O3和UV-B辐射单因子胁迫对大豆生物量和产量均产生不同程度的负效应,而两者的复合作用并不是两个单独作用的简单累加。     

植物对UV-B辐射增强响应的研究进展

分析了大气中臭氧层变薄的现状、原因及光化学机制，阐述了近年来国内外研究紫外线B辐射增强对植物生长发育的影响及其适应性机制，指出当前该研究领域存在的问题及今后加强研究的方向。     

植物次生代谢响应UV-B辐射胁迫的生态学意义

平流层臭氧的减薄已导致地表中波紫外辐射(UV-B,280～320 nm)增强,使植物体内的次生代谢发生改变,而次生代谢产物与抗紫外辐射、抑制昆虫、防止病菌感染和其他食草动物取食、凋落物分解、他感作用等方面存在复杂联系,进而影响生态系统的种类组成、种间关系以及生物的多样性,并导致生态系统的生产力、物质循环、地球化学循环和能量流动等功能的改变,从而影响生态系统的平衡.本文综述了UV-B辐射增强对植物群落和生态系统的影响以及对次生代谢物影响的生态学意义,并展望了该领域的研究方向.     

Ultraviolet-B radiation in a row-crop canopy: an extended 1-D model

A decrease in stratospheric ozone may result in a serious threat to plants, since biologically active short-wavelength ultraviolet-B (UV-B 280–320 nm) radiation will increase even with a relatively small decrease in ozone. Numerous investigations have demonstrated that the effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species competition, susceptibility to disease, and changes in plant structure and pigmentation. To determine the physiological effects on plants of any increases in UV-B radiation, the irradiances at the potential sensitive plant surface need to be known. A number of radiative transfer models exist but because of the importance of sky diffuse radiation to the global UV-B irradiance, models designed to estimate photosynthetically active radiation or total solar radiation may not accurately model the UV-B. This paper compares spatially and temporally averaged measurements of the UV-B canopy transmittance of a relatively dense maize canopy (sky view: 0.27°) to the estimations of two one-dimensional models differing mainly in the handling of sky radiance. The model that considered the distribution of sky radiance tended to underestimate the canopy transmittance, the model that assumed an isotropic sky radiance distribution tended to overestimate the canopy transmittance. However, the assumption concerning the sky radiance distribution accounted for only about 0.01 of the model error. Consequently, the sky radiance distribution is probably not important in modeling such dense crop canopies. The model that overestimated transmittance and had the generally larger errors, a modified Meyers model, used the assumption of uniform leaf angle distribution, whereas in the other model, designated the UVRT model, leaf angle distributions were estimated by sample measurements. Generally this model would be satisfactory in describing the statistically average UV-B irradiance conditions in the canopy. This model may also be applied to other dense plant canopies including forests.     

La与UV-B辐射胁迫对大豆叶片细胞叶绿体超微结构的影响

采用水培法研究了稀土La（Ⅲ）对紫外辐射（UV-B：0.15Wm^-2,0.45Wm^-2）胁迫下大豆（Glycine max）叶片细胞超微结构尤其是对叶绿体结构的影响。结果表明：La（Ⅲ）处理下叶绿体中的类囊体片层排列整齐、有序、清晰;UV-B辐射胁迫下叶绿体内类囊体片层紊乱、膨胀甚至模糊不清,高强度UV-B辐射（T2）对叶绿体的影响大于低强度辐射（T1）;而La（Ⅲ）能够影响UV-B辐射胁迫下叶绿体在细胞环境内的空间分布,减轻UV-B辐射对叶绿体外膜的破坏,使叶绿体内类囊体片层变得有序清晰,且对低强度UV-B辐射（T1）的缓解效果优于高强度（T2）。     

La(Ⅲ)对UV-B辐射胁迫下大豆叶绿素合成与降解影响的机理

采用水培实验方法研究了稀土元素La(Ⅲ)对紫外辐射(UV-B:0.15Wm-2,0.45Wm-2)胁迫下大豆(Glycine max)幼苗的δ-氨基乙酰丙酸(ALA)、胆色素原(PBG)、原叶绿素(酸)(Pchl)、原卟啉IX(Proto-IX)、镁原卟啉(Mg-Proto)等5种叶绿素(Chl)合成中间产物含量及Chl降解关键酶-叶绿素酶(Chlase)活性的影响,从叶绿素的生物合成及降解角度诠释La(Ⅲ)对UV-B辐射胁迫下大豆幼苗叶绿素含量影响的机理。实验结果表明:La(Ⅲ)具有提高叶绿素生物合成中间产物——ALA(δ-氨基乙酰丙酸)、PBG(胆色素原)、Proto-IX(原卟啉IX)、Mg-Proto(镁原卟啉)含量的作用,促进Pchl(原叶绿素)转化为叶绿素,进而缓解UV-B辐射胁迫下中间产物PBG、Proto-IX和Mg-Proto的形成,使叶绿素的生物合成受阻,受阻位点为ALA→PBG。     

Ultraviolet-B exposure induces photo-oxidative damage and subsequent repair strategies in a desert cyanobacterium Microcoleus vaginatus Gom.

Biological soil crusts are important in reversing desertification. Ultraviolet radiation, however, may be detrimental for the development of soil crusts. The cyanobacterium Microcoleus vaginatus can be a dominant species occurring in desert soil crusts all over the world. To investigate the physico-chemical consequences of ultraviolet-B radiation on M. vaginatus, eight parameters including the contents of chlorophyll a, reactive oxygen species, malondialdehyde and proline, as well as the activities of photosynthesis, superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7) and catalase (EC 1.11.1.6) were determined. As shown by the results of determinations, ultraviolet-B radiation caused decreases both in contents of chlorophyll a and in ratios of variable fluorescence over maximum fluorescence that indicate the growth and photosynthesis of M. vaginatus, besides, increases both in levels of reactive oxygen species and in contents of malondialdehyde and proline, while intensified activities of superoxide dismutase, peroxidase and catalase reflecting the abilities of enzymatic preventive substances to oxidative stress of the treated cells. Therefore, ultraviolet-B radiation affects the growth of M. vaginatus and leads to oxidative stress in cells. Under ultraviolet-B radiation, the treated cells can improve their antioxidant abilities to alleviate oxidative injury. The change trends of reactive oxygen species, superoxide dismutase, peroxidase and catalase are synchronous. These results suggest that a balance between the antioxidant system and the reactive oxygen species content may be one part of a complex stress response pathway in which multiple environmental factors including ultraviolet-B radiation affect the survival of M. vaginatus.     

Impact of enhanced ultraviolet-B irradiance on cotton growth, development, yield, and qualities under field conditions

The stratospheric ozone depletion and enhanced solar ultraviolet-B (UV-B) irradiance may have adverse impacts on the productivity of agricultural crops. The effect of UV-B enhancements on agricultural crops includes reduction in yield, alteration in species competition, decrease in photosynthetic activity, susceptibility to disease, and changes in structure and pigmentation. Many studies have examined the influence of supplemental UV-B irradiance on different crops, but the effect of UV-B irradiance on cotton (Gossypium hirsutum L.) crops has received little attention. Cotton is one of the most versatile of all the crops. It is a major fiber crop of the world and a major source of trade and economy in many countries. In this study, we provide quantitative examination of the effects of elevated UV-B irradiance on cotton plant (Sukang 103). The tested cotton crop was grown under natural and four regimes of supplemental UV-B irradiance in the field. With UV-B irradiance increased 9.5% throughout the growing season, the negative impacts on cotton growth included reductions in height of 14%, in leaf area of 29%, and in total biomass of 34%. Fiber quality was reduced and economic yield dropped 72%; an economic coefficient was reduced 58%. A brief discussion is included on how the impacts on cotton contrast with impacts that have been observed in other studies on other plants, including trees.     

Cotton responses to ultraviolet-B radiation: experimentation and algorithm development

The potential impact of an increase in solar ultraviolet-B (UV-B) radiation due to human activity on higher plants has been the subject of many studies. Little work has been carried out so far on cotton responses to enhanced UV-B radiation. The objective of this study was to determine whether or not the current and projected increases in UV-B levels affect cotton growth and development, and to quantify and develop UV-B radiation functional algorithms that can be used in simulation models. Two experiments were conducted during the summer of 2001 using sunlit plant growth chambers in a wide range of UV-B radiations under optimal growing conditions. Leaves exposed to UV-B radiation developed chlorotic and necrotic patches depending on the intensity and length of exposure. Along with changes in visible morphology, cotton canopy photosynthesis declined with increased UV-B radiation. The decline in canopy photosynthesis was partly due to loss of photosynthetic pigments and UV-B-induced decay of leaf-level photosynthetic efficiency (maximum photosynthesis) and capacity (quantum yield) as the leaves aged. The total leaf area was less due to smaller leaves and fewer leaves per plant. Less plant height was closely related to a shorter average internode length rather than a fewer mainstem nodes. The UV-B did not affect cotton major developmental events such as time taken to square, time to flower, and leaf addition rates on the mainstem. Lower biomass was closely related to both smaller leaf area and lower photosynthesis. The critical limit, defined as 90% of optimum or the control, for stem elongation was lower (8.7 kJ m⁻² per day UV-B) than the critical limit for leaf expansion (11.2 kJ m⁻² per day UV-B), indicating that stem elongation was more sensitive to UV-B than leaf expansion. The critical limits for canopy photosynthesis and total dry weight were 7 and 7.3 kJ m⁻² per day, respectively. The identified UV-B-specific indices for stem and leaf growth and photosynthesis parameters may be incorporated into cotton simulation models such as GOSSYM to predict yields under present and future climatic conditions.