植物叶片延迟发光的光谱特性

采用生物超微弱发光探测技术,对绿宝石喜林芋成熟叶片在特定波长下的延迟发光特性进行了测量和分析,得到在400 nm~640 nm波长范围内其延迟发光衰减参数"1/P"随波长变化的光谱特性。实验结果表明:叶片在各个特定波长下"1/P光谱"特性不同;植物叶片延迟发光主要集中在大于500 nm的长波波段,在这个波段内延迟发光强度最大;衰减参数1/P随波长的增加而上升,当波长大于500 nm时,衰减参数1/P相对稳定,在这个波段条件下衰减参数1/P最大。     

光质对绿豆幼苗叶片超微弱发光及叶绿素含量的影响

以绿豆幼苗为试材,测定其叶片超弱发光(UBE)及叶绿素含量在不同光质条件下的变化,并探讨两者之间的关系.结果表明,生长在不同光质下绿豆幼苗叶片的UBE及延迟发光衰减参数1/P都随着其生长不断增强,且生长在白光下绿豆幼苗的UBE是生长在其他光质(红、黄、蓝、绿)下幼苗的2倍以上,而红光、黄光和绿光处理之间无显著差异;生长在白光下的绿豆幼苗叶片叶绿素含量显著高于红、黄、蓝、绿光处理幼苗,而红光和黄光处理又显著高于蓝光和绿光处理.研究发现,光质对绿豆幼苗叶片超弱发光和叶绿素含量影响相似,绿豆幼苗叶片超弱发光可能与叶绿体的发育和光合作用有关.     

绿豆幼苗的超弱发光规律及盐胁迫下的变化

为了研究绿豆幼苗的超弱发光规律及盐胁迫对其的影响和改变,本研究首次采用以EMCCD(电子倍增式CCD)为主的、自行搭建的超弱光图像探测系统,以豫绿2号绿豆为实验材料,检测了绿豆幼苗的自发超弱发光以及在盐胁迫下的改变情况。结果发现:绿豆幼苗自发发光的强度远小于延迟发光的强度,不同的盐胁迫时间对延迟发光强度和自发发光强度的影响各不相同,故可以用延迟发光强度的变化来表征盐胁迫对植物的伤害程度。实验数据的统计结果表明:盐胁迫下绿豆幼苗的发光强度-时间曲线遵循指数衰减规律,说明生物光子具有一定的相干性。本文结果将为农田实时监测植物盐胁迫生理状况提供一种新的光子学手段。     

鸡胚完整脑的光子发射和光激发光研究

利用自制的单光子记录系统,对离体的浸于DMEM培养液中的鸡胚的完整脑所进行的光子发射测量显示出整脑与培养液相比有光子发射.完整脑的光子发射强度与胚龄,鸡胚的健康状况和离体后脑组织的新鲜程度有关.在对完整脑的光激发光测量中观察到一种短寿命的延迟发光,它的衰减过程不服从指数衰减规律而表现出双曲线衰减行为.从生物光子发射归因于生物体内的非定位的相干性电磁场及Frohlish的生命系统中存在着长距离的相干性的理论,讨论了利用生物光子发射研究细胞间通讯、生物的调节及生物与环境关系的意义,以及所检测的光子发射与生物系统自身的相干性电磁场的关系,并提出应从环境对生物系统自身场的影响来理解所测的生物光子发射.     

绿豆和花生的超弱发光

对黄化绿豆幼苗先形态建成过程的超弱发光图象（延迟发光）的初步观察发现：见光培养40min后的绿豆幼苗即可探测到明显的延迟发光;见光时间越长,光诱导的延迟发光强度也越强。从绿豆和花生幼苗的趋弱发光图象来看,生长健壮的幼苗发光较强。其中茎尖和新生幼叶的延迟发光最强,上胚轴、子叶和下胚轴弯钩较强,下胚轴伸长部分次之,根部发光最弱。从不同发育阶段叶片的超弱发光图象来看,光合作用较强、新陈代谢旺盛的成熟叶片的超弱发光较强;光合作用和其它代谢过程相对较弱的叶片（伸展叶、老叶和幼叶）,其超弱发光强度相应较弱。而叶绿素提取液和失活绿叶观测不到超弱发光。此外,对超弱发光光谱的初步研究表明它很可能来自光合作用中叶绿素的发光。这些都暗示,植物的（诱导）超弱发光与光形态建成和光合作用等生长代谢过程密切相关。     

不同光波长下大光金鱼花叶片超微弱发光的光子计数统计

用生物超微弱发光探测技术,对植物叶片的超微弱发光透过滤波片进行测量,并用量子光学中的光子计数分布统计方法得到的结果表明,不同波长下,大光金鱼花叶片的光子计数分布不同,但幼叶和老叶的光子计数分布的规律基本相同,而成熟叶片光子计数分布的规律比较紊乱。     

萤火虫的发光行为及其功能起源

发光生物因其活体能自发荧光而倍受关注,萤火虫(鞘翅目:萤科)是被研究最多的发光生物,因为成虫发光在其性选择以及求偶交配中起着重要作用.由于萤火虫的发光是一个消耗能量(ATP),的化学反应过程,因而其发光在成虫之外的虫态也具有重要意义.本文就萤火虫成虫和幼虫的发光行为、功能意义进行了综述,并结合萤火虫的饲养观察对其卵和蛹的发光行为进行了描述,探讨了卵和蛹的形态阶段发光的生物学功能以及生物荧光的起源进化.这将有助于理解萤火虫及其它生物自发荧光的本质和起源进化过程.     

微弱发光分析技术应用实例(二)

微弱发光测量仪是根据微弱发光分析技术研制的测量样品微弱发光的仪器.BPCL型微弱发光测量仪具有多种重要功能,可满足生物、医学、化学等领域研究与应用的需要.简要介绍微弱发光测量仪在DNA氧化损伤规律的研究中的应用实例.说明了这种技术和仪器的先进性与实用性.     

利用延迟荧光研究DCMU对植物光合的影响

敌草隆（DCMU）阻断植物光合器官类囊体膜上的电子从QA到QB的传递。延迟荧光（DF）是光系统Ⅱ（PSⅡ）反应中心电荷分离效率的内在探针。本文以菠菜叶片作为实验材料,从DF衰减动力学及其总强度的变化研究了DCMU对植物光合作用的影响。DCMU作用后叶片DF衰减动力学曲线表明在快相部分有明显上升趋势,而慢相部分出现下降。不同DCMU浓度处理叶片后延迟荧光强度与叶片光合速率的变化表现出很好的相关性。研究结果表明,植物延迟荧光能很好的表征植物叶片DCMU处理后光合速率的变化。     

海洋甲藻Pyrocistis elegans电激发光的研究

利用培养的海洋甲藻Ｐｙｒｏｃｉｓｔｉｓｅｌｅｇａｎｓ（Ｐ．ｅｌｅｇａｎｓ）作为模型,研究外电场对细胞发光强度－时间曲线的影响。实验结果表明,细胞在外电场作用下所产生的发光（电激发光）行为与细胞本身有关,电激发光是一种延迟发光,其松驰过程不遵从指数衰减规律而表现出双曲线的规律。从物理学的角度讨论了细胞电激发光的相干性及外电场对生命系统和非生命系统的作用的区别,前者更重要的是信息作用,从而提示了研究外电场对细胞作用以及细胞与环境和细胞与细胞间通讯的新方法。     

Nondestructive evaluation of photosynthesis by delayed luminescence in Arabidopsis in Petri dishes

Nondestructive evaluation of photosynthesis is a valuable tool in the field and laboratory. Delayed luminescence (DL) can reflect charge recombination through the backflow of electrons. However, DL detection has not yet been adapted for whole plants in Petri dishes. To compensate for differences in DL decay between sibling Arabidopsis plants grown under the same conditions, we developed a time-sequential double measurement method. Using this method, we examined the influence of photosynthetic electron flow inhibitors, and differences in the DL decay curves were categorized by considering the initial and late phases of the decay curves, as well as their intermediate slopes. The appearance of concavity and convexity in DL curves in Arabidopsis was different from unicellular algae, suggesting complexity in the photosynthetic machinery of higher plants. This detection method should be invaluable for evaluating photosynthetic defects in higher plants under sterile conditions without interrupting plant culture.     

Temporal and spatial regulation of DROOPING LEAF gene expression that promotes midrib formation in rice

Genes involved in the differentiation and development of tissues and organs are temporally and spatially regulated in plant development. The DROOPING LEAF (DL) gene, a member of the YABBY gene family, promotes midrib formation in the leaf and carpel specification in the flower. Consistent with these functions, DL is initially expressed in the central region of the leaf primordia (presumptive midrib) and in the presumptive carpel primordia in the meristem. To understand the regulatory mechanism underlying DL expression, we tried to identify cis-regulatory regions required for temporal and spatial expression of this gene. We found that the cis region responsible for the presumptive midrib-specific expression in the leaf primordia is located in intron 2. Next, we confined the region to a sequence of about 200bp, which corresponds to a conserved non-coding sequence (CNS) identified by phylogenetic footprinting. In addition, a sequence termed DG1, incorporating a 5' upstream region of about 7.4kb, and introns 1 and 2, was shown to be sufficient to induce DL in the presumptive midrib, and to suppress it in other regions in the leaf primordia. By contrast, the regulatory region required for carpel-specific expression was not included in the DG1 sequence. We modified Oryza sativa (rice) plant architecture by expressing an activated version of DL (DL-VP16) in a precise manner using the DG1 sequence: the resulting transgenic plant produced a midrib in the distal region of the leaf blade, where there is no midrib in wild type, and formed more upright leaves compared with the wild type.     

HETEROCHRONY AND HETEROBLASTIC LEAF DEVELOPMENT IN TWO SUBSPECIES OF CUCURBITA ARGYROSPERMA (CUCURBITACEAE)

To date, reports of paedomorphosis at the whole plant or shoot level have been loosely based on whole plant form or on the sequence of leaf shapes produced along the shoot (heteroblasty). However, interpreting the significance of heterochrony in the evolutionary loss or gain of heteroblasty based on mature leaf forms assumes that all leaves with the same shape arose through very similar modes of organogenesis. This study examines this assumption in two subspecies of Cucurbita argyrosperma, one that is wild and heteroblastic and a second that is cultivated and not markedly heteroblastic. All leaves of the cultivar are visually similar to early leaves of the wild subspecies. The cultivar is considered to be the progenitor of the wild subspecies. Scanning electron microscopy and allometry of developing leaves showed that at early nodal positions along the primary shoot, leaf development in both subspecies was similar. At later nodal positions, very young leaves of both subspecies were more similar to each other than to leaves at earlier nodal positions within the same plant at the same stage of development. This early similarity was masked in the mature shapes of later leaves due to subsequent differences in allometric growth. Thus a simple hypothesis of paedomorphosis in which the early leaf form in the progenitor is simply reiterated at later nodal positions in the cultivar is not supported by patterns of leaf development.     

Do canopy herbivores mechanically facilitate subsequent litter decomposition in soil? A pilot study from a Neotropical cloud forest

There is increasing evidence that the above- and belowground components of ecosystems influence one another, thereby controlling key processes such as organic matter decomposition. The aim of this study was to test the hypothesis that leaf herbivory in forest canopies could facilitate subsequent leaf litter decomposition in soils, through changes in leaf quality (i.e., litter palatability) or geometric form (i.e., increased availability of leaf edges made by herbivore damages). In a 9-month field experiment in an Ecuadorian tropical cloud forest, we compared the decomposition rates of entire leaves (EL) and 15?%-damaged leaves (DL) of Ficus cuatrecasana showing similar initial leaf chemistry. We found that DL decomposed significantly faster than EL in early stages of decomposition (i.e., between 0 and 38?days). A parallel experiment using cellulose discs on which we simulated different degrees of damages revealed, however, that geometry per se (i.e., increased edge availability) did not influence decomposition rates. We discuss these contrasting results and propose that higher edge availability in damaged leaves may promote the access of microbes and/or macro-detritivores to leaf tissues thereby enhancing the initial stages of leaf decomposition.     

Effect of partial shading on the photosynthetic apparatus and photosystem stoichiometry in sunflower leaves

The partial shading effect on the photosynthetic apparatus of the sunflower (Helianthus annuus L.) was examined by monitoring oxygen evolution, maximum quantum yield of PSII photochemistry in dark-adapted leaves (F_v/F_m), the chlorophyll (Chl) concentrations and the Rubisco contents, and leaf mass per area (LMA) at the leaf level and by determining the concentrations of cytochrome (Cyt) f and the reaction centres of photosystem (PS) I and PSII at the thylakoid level. In this experiment, partial shading was defined as the shading of 2^nd leaves with shade cloths, and the whole treatment was defined as the covering of the whole individuals with shade cloths. In the leaf level responses, oxygen evolution, LMA, Chl concentrations and Rubisco contents decreased in all shade treatments administered for six days. F_v/F_m remained constant irrespective of the shade treatments. On the other hand, in the thylakoid-level responses, the concentrations of the thylakoid components per unit Chl and the stoichiometry of the two photosystems showed no statistical difference among the shade treatments. The data obtained from the present study indicate that the partial shading affected the leaf-level responses rather than the thylakoid-level responses. The light received at the lower leaves might serve as a factor in the regulation of the leaf properties of the upper leaves due to the whole plant photosynthesis, while this factor did not have an effect at the thylakoid level.     

Induced fluctuations of electric potentials in the apoplast of leaves

Extracellular recordings of electrical potential in leaves of different species by means of band-pass amplifiers showed the occurrence of fast, small changes (spikes) with an amplitude below 1 mV. Local illumination of leaves induced temporal patterns of spikes outside the illuminated region. The light-induced patterns recorded by a given electrode in a particular experimental setup were similar for successive illuminations. The patterns recorded at different sites on the same leaf were different. Locally repetitive patterns of spikes at the electrode outside the illuminated region indicate the occurrence of some signals transmitted from this region to the cells in the neighborhood of the electrode.     

Identification of novel QTLs for seedling and adult plant leaf rust resistance in a wheat doubled haploid population

Pyramiding of genes that confer partial resistance is a method for developing wheat (Triticum aestivum L.) cultivars with durable resistance to leaf rust caused by Puccinia triticina. In this research, a doubled haploid population derived from the cross between the synthetic hexaploid wheat (SHW) (×Aegilotriticum spp.) line TA4152-60 and the North Dakota breeding line ND495 was used for identifying genes conferring partial resistance to leaf rust in both the adult plant and seedling stages. Five QTLs located on chromosome arms 3AL, 3BL, 4DL, 5BL and 6BL were associated with adult plant resistance with the latter four representing novel leaf rust resistance QTLs. Resistance effects of the 4DL QTL were contributed by ND495 and the effects of the other QTLs were contributed by the SHW line. The QTL on chromosome arm 3AL had large effects and also conferred seedling resistance to leaf rust races MJBJ, TDBG and MFPS. The other major QTL, which was on chromosome arm 3BL, conferred seedling resistance to race MFPS and was involved in a significant interaction with a locus on chromosome arm 5DS. The QTLs and the associated molecular markers identified in this research can be used to develop wheat cultivars with potentially durable leaf rust resistance.     

傅里叶变换红外光谱(FTIR)技术对滇龙胆组织培养的研究

野生药用植物资源的不断减少,使得寻找其原植物的合适替代品显得尤为重要。利用组培材料代替野生药用植物作为药源已取得重大进展,但利用傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)技术筛选合适的组培材料作为野生药用植物替代资源方面的应用鲜有报道。本研究采用FTIR结合偏最小二乘判别分析(partial least squares discriminant analysis,PLS-DA)对滇龙胆组织培养形成的愈伤组织(肉质部、茎、叶)、增殖苗(肉质部、茎、叶)、生根苗(根、茎、叶)进行比较。结果显示:(1)从原始FTIR光谱图上看,滇龙胆肉质部和根部峰形相似,茎和叶峰形相似;(2)二阶导数光谱图扩大了样品间的差异。在龙胆苦苷的主要吸收峰1612 cm-1附近,吸收峰强度依次为:生根苗叶增殖苗叶和生根苗茎增殖苗茎愈伤组织叶,愈伤组织茎及肉质部、增殖苗肉质部和生根苗根部在该处无吸收峰;(3)PLS-DA得分图表明,同一组培阶段相同组织部位样品聚集在一起,而愈伤组织、增殖苗、生根苗及其各组织部位能够较好的分开。其中:肉质部、根部与茎叶之间距离较远,表明其化学成分和含量可能差异较大;肉质部和根部样品间距离较近,茎和叶样品间距离也较近。二阶导数光谱图显示,组培材料有望代替其原植物满足药用需求;若以龙胆苦苷含量为评价对象,生根苗叶则可能具有更大的开发潜能,有望代替野生滇龙胆以缓解其资源稀缺局面。本研究结果表明,采用傅里叶变换红外光谱法可以简便有效地对药用植物不同组培阶段不同组织部位的替代潜力及开发利用进行初步评估。     

水稻对叶瘟和穗瘟部分抗性的遗传分析

在一个水稻籼籼交重组自交系群体中,选用由感病株系构成的2个亚群体和2个不同的稻瘟病菌小种,进行了水稻对叶瘟部分抗性的QTL定位,还选用由感病而且抽穗期相近的株系构成的亚群体和另一个病菌小种,进行了水稻对穗瘟部分抗性的QTL定位,将病叶面积百分比(DLA)、病斑大小(LS)和病斑数(LN)作为对叶瘟部分抗性的性状,将病斑长度(LL)和孢子量(CA)作为对穗瘟部分抗性的性状。所构建的图谱包含168个标记。应用QTLMapper 1．01b,共检测到11个表现主效应的QTL和28对双因子互作,有3个表现主效应的QTL参与对同一性状的互作。QTL的主效应对单一性状的贡献率为4．7％～38．8％,而上位性效应对单一性状的贡献率为16．0％～51．7％,QTL的主效应对大多数性状的贡献率小于互作效应,表明互作效应对于部分抗性的重要作用。对穗瘟部分抗性的两个性状LL和CA,所检测到QTL总效应的贡献率分别达到70．6％和82．6％,表明由排除了主效抗病基因的感病株系组成的亚群体适合于进行部分抗性QTL定位。