遮荫对‘保佳红’桃树叶片快速叶绿素荧光诱导动力学曲线的影响

以3年生桃品种‘保佳红’为试材,于不同生育时期采用人工遮阴的方法,在叶片生长的不同时期分别设置100%(CK)、80%、60%、40%和20% 自然光照的5个光照强度处理,利用快速叶绿素荧光诱导动力学曲线分析技术,研究了不同光强对桃树叶片快速叶绿素荧光诱导动力学曲线及其参数的影响。结果表明：（1）桃树各生长时期的叶片最大荧光值均随着光照强度的减弱而依次升高。（2）在PSⅡ能量分配比率方面,遮阴下的叶片提高了用于电子传递的量子比率(φ_Eo),降低了用于热耗散的的量子比率(φ_Do)。（3）在PSⅡ反应中心活性方面,遮阴使得单位反应中心吸收的光能(ABS/RC)、捕获的光能(TRo/RC)、用于传递电子的能量(ETo/RC)和用于热耗散的能量(DIo/RC)均下降。（4）各时期不同光强处理的最大光化学效率F_v/F_m均在中午时段出现下降,且光照强度越大,降幅越大,说明桃叶在中午会出现强光抑制。研究认为：在遮阴条件下,桃叶天线色素吸收和捕获的光能减少,PSⅡ反应中心活性降低,但其可以通过增加能量在电子传递方面的分配比率来提高对光能的利用。     

快速叶绿素荧光诱导动力学分析在光合作用研究中的应用

JIP-测定(JIP-test)是以生物膜能量流动为基础建立的分析方法.利用该方法可以获得有关光系统Ⅱ的大量信息.文章介绍了快速叶绿素荧光诱导动力学曲线的定义、数据分析方法及相关参数的意义,并举例说明如何利用该方法分析不同环境条件对光合机构主要是PSⅡ的供体侧、受体侧及PSⅡ反应中心的影响.     

叶绿素荧光技术在植物环境胁迫研究中的应用

近年来叶绿素荧光技术在植物,包括藻类对各种环境胁迫响应的机理和应用研究中起着越来越重要的作用．本文简述了这方面的部分工作和进展．     

叶绿素荧光动力学在植物抗性生理学,生态学和农业现代化中的应用

概况中国是个农业大国,农业在我国国民经济及人民生活中都占有极重要的地位。为了保证我国农业能以较高的速度持续地向前发展,除了要有正确的农业政策外,就必须依靠科学技术。为此,我们应该密切注视国际科技发展新动向,及时抓住有重要发展前景的新技术,加以重点支持与扶植,使它能够在我国农业现代化的过程中发挥作用。     

光激活荧光蛋白及其在植物分子细胞生物学研究中的应用

光激活荧光蛋白是指用特定光照射时, 其荧光特性发生显著改变的一类荧光蛋白。借助光激活荧光蛋白的这种特性,可以实现对活细胞、细胞器或胞内分子的时空标记和追踪。该文介绍了目前光激活荧光蛋白的性质, 并从多个方面对其应用进行了概括, 包括分子标记与动态分析、蛋白质相互作用、细胞器及细胞组分动态研究、细胞追踪以及在光激活定位显微镜中的应用等, 且对目前光激活荧光蛋白在植物分子细胞生物学中的应用进行了详细介绍。     

光激活荧光蛋白及其在植物分子细胞生物学研究中的应用

光激活荧光蛋白是指用特定光照射时,其荧光特性发生显著改变的一类荧光蛋白。借助光激活荧光蛋白的这种特性,可以实现对活细胞、细胞器或胞内分子的时空标记和追踪。该文介绍了目前光激活荧光蛋白的性质,并从多个方面对其应用进行了概括,包括分子标记与动态分析、蛋白质相互作用、细胞器及细胞组分动态研究、细胞追踪以及在光激活定位显微镜中的应用等,且对目前光激活荧光蛋白在植物分子细胞生物学中的应用进行了详细介绍。     

短尾铁线莲叶绿素荧光特性研究

运用便携式光合气体分析系统(LI-6400)对短尾铁线莲(Clematis brevicaudata)的叶绿素荧光动力学曲线、淬灭分析、荧光光曲线以及荧光ACI曲线等生理特性进行测定和对比分析。结果表明:随光照时间的增加,短尾铁线莲的荧光参数ETR、qP和NPQ逐渐上升并在28 min左右达到稳定。最大荧光产量Fm′在叶片转入黑暗后逐渐上升,在52 min左右趋于稳定;NPQ则开始下降,在50 min左右达到稳定。PhiPS2和PhiCO2呈线性正相关(P<0.01)并随着光照强度的增加而减小。短尾铁线莲对CO2浓度的变化十分敏感,在50~200μmol.mol-1范围内,CO2浓度的增加可显著提高其PhiPS2和PhiCO2的值,增加CO2浓度是提高短尾铁线莲光合速率的有效途径。     

LEA蛋白及其在植物抗逆改良中的应用

干旱、盐碱、高温和寒冷等逆境制约着植物的生长发育。植物中含有一组亲水性极强的蛋白,称为胚胎发育晚期丰富蛋白(late embryogenesis abundant,LEA蛋白),在自然条件下这种蛋白质一般在种子发育晚期积累,其对多种非生物胁迫具有很强的抵抗能力,并能响应干旱、寒冷、高盐和ABA等信号。LEA蛋白通过保持细胞渗透压、保护细胞膜结构、作为分子伴侣保护其他蛋白等方式维持植物正常的代谢反应。就LEA蛋白的分类、结构、抗逆机制以及在植物抗逆改良中的应用进行了简要综述。     

WRKY转录因子在植物抗逆生理中的研究进展

转录因子是一类在生物生命活动过程中起到调控作用的重要因子,参与了各种信号转导和调控过程,可以直接或间接结合在顺式作用元件上,实现调控目标基因转录效率的抑制或增强,从而使植物在应对逆境胁迫下做出反应。WRKY转录因子在大多数植物体内都有分布,是一类进化非常保守的转录因子家族,参与植物生长发育以及响应逆境胁迫的生理过程。众多研究表明,WRKY转录因子在植物中能够应答各种生物胁迫,如细菌、病毒和真菌等;多种非生物胁迫,包括高温、冷害、高光和高盐等;以及在各种植物激素,包括茉莉酸(JA)、水杨酸(SA)、脱落酸(ABA)和赤霉素(GA)等,在其信号传递途径中都起着重要作用。WRKY转录因子家族蛋白至少含有一段60个氨基酸左右的高度保守序列,被称为WRKY结构域,其中WRKYGQK多肽序列是最为保守的,因此而得名。该转录因子的WRKY结构域能与目标基因启动子中的顺式作用元件Wbox(TTGAC序列)特异结合,从而调节目标基因的表达,其调控基因表达主要受病原菌、虫咬、机械损伤、外界胁迫压力和信号分子的诱导。该文介绍了植物WRKY转录因子在植物应对冷害、干旱、高盐等非生物胁迫与病菌、虫害等生物胁迫反应中的重要调控功能,并总结了WRKY转录因子在调控这些逆境胁迫反应过程中的主要生理机制。     

A portable, microprocessor operated instrument for measuring chlorophyll fluorescence kinetics in stress physiology

A portable instrument for measuring chlorophyll fluorescence induction kinetics is described and examples of measurements are given. The instrument is centered around a statistically-mixed bifurcated optical fiber. One fiber branch guides the actinic light to the sample, whereas the other branch carries the emitted chlorophyll fluorescence to the photodetector. Scattered actinic light is cut out from the detector by a red interference filter. The instrument measures fast as well as slow fluorescence induction kinetics, but is particularly well designed for analyzing fast kinetics. The high time resolution and strong, variable actinic light mean that both F_o (non-variable fluorescence) and F_m (maximal fluorescence at the P-peak) are well defined. A built in microprocessor unit with attached memory stores the fluorescence induction curve and calculates key fluorescence parameters such as F_o, F_m, F_v (variable fluorescence equals F_m?F_o), F_v/F_m (the photochemical efficiency of photosystem II) and t_1/2 (half rise time from F_o, to F_m). These values are digitally displayed after each recording and they (or the whole induction curve) can be stored in a memory and later retrieved. Because of a flexible setting of the instrument it can be used with high accuracy both for optically thick leaves and for diluted suspensions of algae or chloroplasts. A simple, light weight clamp cuvette for dark adaptation of leaves has been developed. It is equipped with a gate allowing the optical fiber to be inserted without daylight reaching the dark adapted portion of the leaf. The instrument has been developed for rapid monitoring of changes in activities and organization of the photosynthetic apparatus in vivo when plants are exposed to environmental stress both in the field and in the laboratory. Examples of measurements are given for differently treated leaves of Pinus sylvestris, Salix sp., Betula verrucosa, Zea mays, Epilobium angustifo-lium and for chloroplast thylakoids isolated from Spinacia oleracea.     

Chlorophyll a fluorescence kinetics of mung bean (Vigna radiata L.) grown under artificial continuous light

Continuous light can be used as a tool to understand the diurnal rhythm of plants and it can also be used to increase the plant production. In the present research, we aimed to investigate the photosynthetic performance of V. radiata under continuous light as compared with the plants grown under normal light duration. Chlorophyll a fluorescence transient (OJIP test) technique was used to understand the effect on various stages of photosynthesis and their consequences under continuous light condition. Various Chl a Fluorescence kinetic parameters such as Specific energy fluxes (per Q_A-reducing PSII reaction center (RC)) (ABS /RC; TR₀/RC; ET₀/RC; DI₀/RC), phenomenological fluxes, leaf model, (ABS/CSm; TR/CSm; ETo/CSm), Quantum yields and efficiencies (φPo; φEo; Ψo) and Performance index (PI_abs) was extracted and analysed in our investigation. Conclusively, our study has revealed that continuous light alters the photosynthetic performance of V. radiata at a different point but also improve plant productivity.     

不同强度的红光和蓝光下菜豆叶片的荧光特性

光质和光强均是影响植物光合作用的重要外部因素,该文以菜豆(Phaseolus vulgaris)为材料,通过叶绿素荧光技术比较研究了菜豆叶片在不同光强的红光和蓝光下叶绿素荧光特性的变化规律。结果表明:随着红光和蓝光光强的增加,菜豆叶片的光适应下的最大光化学效率(Fv'/Fm')呈下降趋势,但与在红光下相比,蓝光下叶片的Fv'/Fm'值较高。随着蓝光光强的增加,菜豆叶片PSⅡ实际光化学效率(Y(Ⅱ))和光化学猝灭系数(q P和q L)先呈上升趋势之后逐渐趋于平稳;而随着红光光强的增加,以上参数呈下降趋势。随着红光和蓝光光强的增加,非光化学猝灭系数(NPQ)、相对电子传递速率(ETR)以及调节性能量耗散的量子产量Y(NPQ)均呈上升趋势,但与在红光下相比,蓝光下叶片NPQ和Y(NPQ)的值较低,而ETR值较高。非调节性能量耗散产量Y(NO)随着红光光强增加而呈上升趋势,而随着蓝光光强增加呈下降趋势。综上可见,随着光强的增加菜豆叶片的光化学效率呈降低趋势,但叶片在蓝光下的光化学吸收和利用效率高于红光。研究结果可为植物对光强和光质的响应提供一定的参考。     

Relaxation of the non-photochemical chlorophyll fluorescence quenching in diatoms: kinetics,components and mechanisms

Diatoms are especially important microorganisms because they constitute the larger group of microalgae. To survive the constant variations of the light environment, diatoms have developed mechanisms aiming at the dissipation of excess energy, such as the xanthophyll cycle and the non-photochemical chlorophyll (Chl) fluorescence quenching. This contribution is dedicated to the relaxation of the latter process when the adverse conditions cease. An original nonlinear regression analysis of the relaxation of non-photochemical Chl fluorescence quenching, qN, in diatoms is presented. It was used to obtain experimental evidence for the existence of three time-resolved components in the diatom Phaeodactylum tricornutum: qNf, qNi and qNs. qNf (s time-scale) and qNs (h time-scale) are exponential in shape. By contrast, qNi (min time-scale) is of sigmoidal nature and is dominant among the three components. The application of metabolic inhibitors (dithiothreitol, ammonium chloride, cadmium and diphenyleneiodonium chloride) allowed the identification of the mechanisms on which each component mostly relies. qNi is linked to the relaxation of the ΔpH gradient and the reversal of the xanthophyll cycle. qNs quantifies the stage of photoinhibition caused by the high light exposure, qNf seems to reflect fast conformational changes within thylakoid membranes in the vicinity of the photosystem II complexes.     

不同微生境中水光温变化对毛尖紫萼藓叶绿素荧光特性的影响

毛尖紫萼藓（Grimmia pilifera）多生长在裸岩表面且具有多种微生境,其生长过程受到水分、光照和温度等环境因素的交互影响,但其光合生理特征如何响应这种变化的环境条件尚不清楚。开展原位（荫蔽和向阳裸岩2种微生境）和室内模拟实验,分析了不同水分（模拟降水量和降水频次）、光照、温度及其复合梯度处理对毛尖紫萼藓叶绿素荧光特性的影响。原位实验结果显示荫蔽生境原位生长毛尖紫萼藓光化学效率显著高于向阳生境。在室内相同培养条件下,脱水过程中来自荫蔽生境植株有效光合效率保持时间比向阳生境明显缩短,表现出较低的脱水耐受性。水-光-温复合模拟实验显示,降水频次和光-温变化对毛尖紫萼藓光化学效率均有极显著影响且存在一定的交互作用,而降水量的影响相对较弱;弱光低温及1次/（2 d）的降水频率条件下毛尖紫萼藓具有最高的光合活性。总体来看,荫蔽生境、弱光低温条件及中等频次降水有利于毛尖紫萼藓生长,但向阳生境毛尖紫萼藓则具有更强的环境耐受性。     

Profiles of light absorption and chlorophyll within spinach leaves from chlorophyll fluorescence

Chlorophyll fluorescence was used to estimate profiles of absorbed light within chlorophyll solutions and leaves. For chlorophyll solutions, the intensity of the emitted fluorescence declined in a log–linear manner with the distance from the irradiated surface as predicted by Beer's law. The amount of fluorescence was proportional to chlorophyll concentration for chlorophyll solutions given epi‐illumination on a microscope slide. These relationships appeared to hold for more optically complex spinach leaves. The profile of chlorophyll fluorescence emitted by leaf cross sections given epi‐illumination corresponded to chlorophyll content measured in extracts of leaf paradermal sections. Thus epifluorescence was used to estimate relative chlorophyll content through leaf tissues. Fluorescence profiles across leaves depended on wavelength and orientation, reaching a peak at 50–70 µm depth. By infiltrating leaves with water, the pathlengthening due to scattering at the airspace : cell wall interfaces was calculated. Surprisingly, the palisade and spongy mesophyll had similar values for pathlengthening with the value being greatest for green light (550 > 650 > 450 nm). By combining fluorescence profiles with chlorophyll distribution across the leaf, the profile of the apparent extinction coefficient was calculated. The light profiles within spinach leaves could be well approximated by an apparent extinction coefficient and the Beer–Lambert/Bouguer laws. Light was absorbed at greater depths than predicted from fibre optic measurements, with 50% of blue and green light reaching 125 and 240 µm deep, respectively.     

Applications of chlorophyll fluorescence: In photosynthesis research,stress physiology,hydrobiology and remote sensing

Book reviews

Applications of chlorophyll fluorescence: In photosynthesis research, stress physiology, hydrobiology and remote sensingH.K. Lichtenthaler (Ed.), Proceedings of the International Chlorophyll Fluorescence Symposium, 6–8 June 1988. Dordrecht: Kluwer Academic Publishers, 1988. xiv + 366 pages. £54. ISBN 90-247-3787-7     

Variable chlorophyll fluorescence and its use for assessing physiological condition of plant photosynthetic apparatus

Analysis of plant behavior under diverse environmental conditions would be impossible without the methods for adequate assessment of the processes occurring in plants. The photosynthetic apparatus and its reaction to stress factors provide a reliable source of information on plant condition. One of the most informative methods based on monitoring the plant biophysical characteristics consists in detection and analysis of chlorophyll a fluorescence. Fluorescence is mainly emitted by chlorophyll a from the antenna complexes of photosystem II (PSII). However, fluorescence depends not only on the processes in the pigment matrix or PSII reaction centers but also on the redox reactions at the PSII donor and acceptor sides and even in the entire electron transport chain. Presently, a large variety of fluorometers from various manufacturers are available. Although application of such fluorometers does not require specialized training, the correct interpretation of the results would need sufficient knowledge for converting the instrumental data into the information on the condition of analyzed plants. This review is intended for a wide range of specialists employing fluorescence techniques for monitoring the physiological plant condition. It describes in a comprehensible way the theoretical basis of light emission by chlorophyll molecules, the origin of variable fluorescence, as well as relations between the fluorescence parameters, the redox state of electron carriers, and the light reactions of photosynthesis. Approaches to processing and analyzing the fluorescence induction curves are considered in detail on the basis of energy flux theory in the photosynthetic apparatus developed by Prof. Reto J. Strasser and known as a “JIP-test.” The physical meaning and relation of each calculated parameter to certain photosynthetic characteristics are presented, and examples of using these parameters for the assessment of plant physiological condition are outlined.