Fractal Analysis of Plant Root Systems

The morphology of root systems of crop plants was analysed byfractal geometry using an image processing system. Results indicatethat these root systems have a fractal structure (D; 1.48     

High Resolution Imaging of Plant Tissues10

Connelly, A., Lohman, J. A. B., Loughman, B. C., Quiquampoix,H. and Ratcliffe, R. G. 1987. High resolution imaging of planttissues by NMR.—J. exp. Bot. 38: 1713–1723. NMR images of living plant tissues were recorded at a ¹H frequencyof 200 MHz using a high resolution imaging technique that gavean in-plane pixel resolution of 50 µm x 50 µm orbetter. Images with interpretable contrast were obtained fromgerminating seeds, the roots of seedlings and the stems of youngplants. The expected structural features of these tissues werereadily observed including, in Mn²⁺ loaded tissue, the xylemvessels of maize root sections. Preliminary experiments on H₂O-D₂Oexchange in maize roots, on the uptake of Mn²⁺ by maize rootsand on the germination of seeds in situ demonstrate that thenon-invasive method of NMR mini-imaging has the potential tocomplement existing techniques for physiological investigationsin plant tissues. Key words: NMR imaging, water content, ion uptake     

High Resolution 3D Imaging of Ex-Vivo Biological Samples by Micro CT

Non-destructive volume visualization can be achieved only by tomographic techniques, of which the most efficient is the x-ray micro computerized tomography (μCT).High resolution μCT is a very versatile yet accurate (1-2 microns of resolution) technique for 3D examination of ex-vivo biological samples^{1, 2}. As opposed to electron tomography, the μCT allows the examination of up to 4 cm thick samples. This technique requires only few hours of measurement as compared to weeks in histology. In addition, μCT does not rely on 2D stereologic models, thus it may complement and in some cases can even replace histological methods^{3, 4}, which are both time consuming and destructive. Sample conditioning and positioning in μCT is straightforward and does not require high vacuum or low temperatures, which may adversely affect the structure. The sample is positioned and rotated 180° or 360°between a microfocused x-ray source and a detector, which includes a scintillator and an accurate CCD camera, For each angle a 2D image is taken, and then the entire volume is reconstructed using one of the different available algorithms^5-7. The 3D resolution increases with the decrease of the rotation step. The present video protocol shows the main steps in preparation, immobilization and positioning of the sample followed by imaging at high resolution.     

Stimulation of Vesicular-Arbuscular Mycorrhizal Fungi by Mycotrophic and Nonmycotrophic Plant Root Systems

Transformed root cultures of three nonmycotrophic and one mycotrophic plant species stimulated germination and hyphal growth of the vesicular-arbuscular mycorrhizal fungus Glomus etunicatum (Becker & Gerd.) in a gel medium. However, only roots of the mycotrophic species (carrot) supported continued hyphal exploration after 3 to 4 weeks and promoted appressoria formation by G. etunicatum.     

High Heterogeneity of Root Carbon Allocation Affects Root Turnover Rate and Production of Bothriochloa ischaemum Under Drought Stress

Journal of Plant Growth Regulation - The mechanism that causes the difference in carbon (C) turnover rate in root populations is unclear. The carbon utilization strategy is assumed to be the main...     

地黄对于糖尿病大鼠微炎症状态的作用

目的:研究地黄对于糖尿病模型大鼠血糖以及微炎症状态的作用。方法:采用高糖高脂饲料喂养加腹腔注射链尿佐菌素(STZ)破坏胰岛细胞的方法构建糖尿病大鼠模型。将大鼠分为空白对照组、糖尿病模型组与药物治疗组。空白对照组以及糖尿病模型组给予蒸馏水,用药组分别给予不同剂量丹参、地黄、格列本脲灌胃治疗,每日一次,连续60日。应用血糖仪动态监测血糖,ELISA法检测血清中超敏C反应蛋白(Hs-CRP)、白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)浓度变化情况,以观察地黄对血糖及糖尿病微炎症状态的改善效果。结果:造模成功后,糖尿病大鼠血糖明显升高(P0.05),血液中炎症因子Hs-CRP、IL-6、TNF-α含量升高,与空白对照组相比,差异显著(P0.05)。地黄治疗后血糖明显降低(P0.05),血液中炎症因子Hs-CRP、IL-6、TNF-α含量均显著减低,差异均有统计学意义(P0.05)。结论:地黄可以明显降低糖尿病大鼠的血糖水平,显著改善糖尿病大鼠的微炎症状态。     

Disentangling the Effects of Root Foraging and Inherent Growth Rate on Plant Biomass Accumulation in Heterogeneous Environments: A Modelling Study

Empirical evidence indicates that fast-growing species generallydisplay a higher degree of selective root placement in heterogeneousenvironments than slow-growing species. Such root foraging isaccomplished by root morphological responses, but since somemorphological responses are simply the result of enhanced growthof the roots in the enriched patch it is difficult to separatethe effects of root foraging and growth rate on the biomassaccumulation of species in heterogeneous environments. Herea simple model is presented to disentangle these effects. Rootforaging is incorporated as the selective allocation of rootbiomass per unit time to the nitrogen-rich patch. Growth ratedifferences among the model plants result from differences innitrogen utilization efficiency. In the model, the degree ofselective root placement can be varied independently of growthrate. The model shows that when plants are compared at a commonpoint in time, selective root placement and growth rate interactpositively with respect to the enhancement of plant biomassaccumulation in heterogeneous compared to homogeneous environments.However, by evaluating the model at a common plant biomass,the main and interactive effects of growth rate are eliminated.These results suggest that growth rate by itself does not conferan advantage in terms of resource acquisition and biomass accumulationin heterogeneous environments. Only the selective placementof resource acquiring structures (such as roots) leads to suchbenefits. The essential differences between foraging and growth,as well as the consequences of differences in foraging abilityand growth rate between species on competition for a limitedresource, are discussed. Copyright 1999 Annals of Botany Company Environmental heterogeneity, foraging, growth rate, model, nitrogen uptake, nitrogen utilization, patchiness, plant growth, plasticity, root placement.     

一类食饵具有常数投放率系统的恢复率

在现实的生态系统中,特别当捕食者的密度大或捕食能力强时,人们常采用食饵补充的方式来控制捕食者和食饵种群数量的稳定,以达到生态平衡．本文在Chisholm,R．A．和Filotas,E．研究的捕食-食饵模型基础上,定义了食饵具有常数投放率的捕食系统,讨论了此系统的恢复率与食饵最大容量之间的关系以及投放率对恢复率和预警长度的影响．最后通过算例分析了递减的恢复率作为系统转移的指示器与投放率与食饵最大容量的关系,说明食饵的投放率可增强预警效果．     

A High‐Resolution Approach to Mapping Energy Flows through Water Infrastructure Systems

Using data from the water service area of the East Bay Municipal Utility District in Northern California, we develop and discuss a method for assessing, at a high resolution, the energy intensity of water treated and delivered to customers of a major metropolitan water district. This method extends previous efforts by integrating hourly data from supervisory control and data acquisition systems with calculations based on the actual structure of the engineered infrastructure to produce a detailed understanding of energy use in space and time within the territory of a large‐scale urban water provider. We found significant variations in the energy intensity of delivered potable water resulting from seasonal and topographic effects. This method enhances our understanding of the energy inputs for potable water systems and can be applied to the entire delivery and postuse water life cycle. A nuanced understanding of water's energy intensity in an urban setting enables more intelligent, targeted efforts to jointly conserve water and energy resources that take seasonal, distance, and elevation effects into account.     

113 Toward Resolution of the Fuzzy Nodes in Green Plant Phylogeny

We are funded to resolve the primary pattern of evolutionary diversification among green plants, and to establish a model for doing so that will be applicable to other groups of organisms with long evolutionary histories. To achieve this goal we will 1) complete a matrix of whole genome sequences for chloroplast and mitochondria and develop either nuclear or organellar bacterial artificial chromosome, BAC, libraries for about 50 representatives of the critical deep-branching lineages of green plants; 2) produce a comprehensive set of comparable morphological and ultrastructural data for these same taxa; 3) incorporate inferences from across the phylogenetic hierarchy in green plants using methods designed to permit scaling across studies. We shall indicate how this work will link to other research being conducted on green plants and various scales, especially the concatenation of our data sets with theirs. We will present the fuzzy nodes we have chosen to resolve and discuss our choices of taxa in this preliminary report. Funded by NSF's Tree of Life Program, 2002–2006, DEB #0228655 (lead institution), #228432, #0228679, #0228729, #0228660, #0228576.     

播娘蒿下胚轴高频率再生植株因素的研究

以播娘蒿（Descurainia sophia)下胚轴为外植体,研究影响其分化的若干因素。结果表明：用附加2,4－D的培养基,对下胚轴切段预培养5d可提高分化频率;1.7mg/L AgNO3对分化出芽有很大促进作用,最佳激素组合为2.0mg/L 6-BA 0.2mg/L NAA;黄化苗的下胚轴比绿苗的下胚轴对激素反应更敏感,最高分化频率可达86.05%。再生芽转至1／2MS 0.5mg/L NAA 0.5mg/L IBA的培养基中,生根率100％。     

The Root Herbivore History of the Soil Affects the Productivity of a Grassland Plant Community and Determines Plant Response to New Root Herbivore Attack

Insect root herbivores can alter plant community structure by affecting the competitive ability of single plants. However, their effects can be modified by the soil environment. Root herbivory itself may induce changes in the soil biota community, and it has recently been shown that these changes can affect plant growth in a subsequent season or plant generation. However, so far it is not known whether these root herbivore history effects (i) are detectable at the plant community level and/or (ii) also determine plant species and plant community responses to new root herbivore attack. The present greenhouse study determined root herbivore history effects of click beetle larvae (Elateridae, Coleoptera, genus Agriotes) in a model grassland plant community consisting of six common species (Achillea millefolium, Plantago lanceolata, Taraxacum officinale, Holcus lanatus, Poa pratensis, Trifolium repens). Root herbivore history effects were generated in a first phase of the experiment by growing the plant community in soil with or without Agriotes larvae, and investigated in a second phase by growing it again in the soils that were either Agriotes trained or not. The root herbivore history of the soil affected plant community productivity (but not composition), with communities growing in root herbivore trained soil producing more biomass than those growing in untrained soil. Additionally, it influenced the response of certain plant species to new root herbivore attack. Effects may partly be explained by herbivore-induced shifts in the community of arbuscular mycorrhizal fungi. The root herbivore history of the soil proved to be a stronger driver of plant growth on the community level than an actual root herbivore attack which did not affect plant community parameters. History effects have to be taken into account when predicting the impact of root herbivores on grasslands.     

The Pattern of Respiration Rate in the Vegetative Barley Plant

In two experiments with young barley plants, respiration rate,carbohydrate content and growth rate of the whole plant weremeasured. When 18-day-old plants were darkened the rate of respirationand the levels of soluble carbohydrate fell in parallel overthe following 30 h. When the dark respiration rate of plantswas followed from 7 to 24 days respiration rate and solublecarbohydrate levels did not change together, nor did the respirationrate (R) follow the empirical relationship with photosynthesis(P) and d. wt (W) R = aW + bP, suggested by McCree. Hordeum distichum L. (Lam), barley, respiration, carbohydrate content