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131.
Uncultivated plants growing on disturbed sites may be useful for assessing the bioavailability of some metals in soils, and thus the potential for metal mobilization up the terrestrial food chain, an important element in ecological risk assessment. A planted chicory cultivar (Cichorium intybus L. var. foliosum Hegi.) and the uncultivated plants horseweed (Canada fleabane) (Erigeron canadensis L.) and dogfennel (Eupatorium capillifolium (Lam.) Small) were evaluated for their ability to act as index plant species for soil Cd, Cr, Ni, and V at two field sites where these metals had been applied five yr previously to two highly weathered sandy Ultisols. Soil Cd was available to all analyzed plant tissues of all three plant species at both sites, particularly on the sandier Blanton soil. Chicory was an effective index plant for Cd on the finer textured Orangeburg soil but functioned as an indicator plant (toxicity symptoms were observed) on the sandier Blanton soil. Horseweed and dogfennel were effective index plants for Cd in both contaminated soils. Soil Cr, Ni, and V were less bioavailable than soil Cd and plant metal uptake was more sensitive to residual soil Cr, Ni, and V than was soil extraction with double acid. Horseweed and chicory may have potential as index plants for soil Cr. Chicory may have potential as a Ni index plant. Chicory and dogfennel may have potential as V index plants. 相似文献
132.
ChimpanzeesPan troglodytes in Kibale National Park, Uganda occasionally swallow entire leaves ofRubia cordifolia (Rubiaceae) without chewing them. The leaves are subsequently egested with minimal damage and no sign of any significant
digestion. Similar behavior reported elsewhere has been proposed to have medicinal effects. Here we test the hypothesis that
chemical components in swallowed leaves have negative effects on intestinal nematodes. We used anin vitro assay to detect the effects of methanol extracts ofR. cordifolia leaves on nematodes,Strongyloides spp., cultured from feces. Control extracts were distilled water, methanol solution, and methanol extracts of food items
that were chewed, rather than swallowed, by chimpanzees. Effects of experimental or control solutions were assayed by nematode
motility. There was no difference in nematode motility among control and experimental extracts. This study therefore did not
support the hypothesis of pharmacological self-medication via leaf swallowing. 相似文献
133.
Atmospheric ammonia (NH3) from various anthropogenic sources has become a serious problem for natural vegetation. Ammonia not only causes changes in plant nitrogen metabolism, but also affects the acid-base balance of plants. Using the pH-sensitive fluorescent dyes pyranine and esculin, cytosolic and vacuolar pH changes were measured in leaves of C3 and C4 plants exposed for brief periods to concentrations of NH3 in air ranging from 1.33 to 8.29 mol NH3 · mol-1 gas (0.94–5.86 mg · m-3). After a lag phase, uptake of NH3 from air at a rate of 200 nmol NH3 · m - 2 leaf area · s- 1 into leaves of Zea mays L. increased pyranine fluorescence indicating cytosolic alkalinisation. The increase was much larger in the dark than in the light. In illuminated leaves of the C3 plant Pelargonium zonale L. and the C4 plants Z. mays and Amaranthus caudatus L., NH3-dependent cytosolic alkalinisation was particularly pronounced when CO2 was supplied at very low levels (16 or 20 mol CO2 · mol- 1 gas, containing 210 mmol O2 · mol- 1 gas). An increase in esculin fluorescence, which was smaller than that of pyranine, was indicative of trapping of some of the NH3 in the vacuoles of leaves of Spinacia oleracea L. and Z. mays. Photosynthesis and transpiration remained unchanged during exposure of illuminated leaves to NH3, yielding an influx of 200 nmol NH3 · m-2 leaf area · s-1 for up to 30 min, the longest exposure time used. Both CO2 and O2 influenced the extent of cytosolic alkalinisation. At 500 mol CO2 · mol-1 gas the cytosolic alkalinisation was suppressed more than at 16 or 20 mol CO2 · mol-1 gas. The suppressing effect of CO2 on the NH3induced alkalinisation was larger in illuminated leaves of the C4 plants Z. mays and A. caudatus than in leaves of the C3 plant P. zonale. A reduction of the O2 concentration from 210 to 10 mmol O2 · mol -1 gas, which inhibits photorespiration, increased the NH3induced cytosolic alkalinisation in C3 plants. Suppression by CO2 or O2 of the alkaline pH shift caused by the dissolution and protonation of NH3 in queous leaf compartments, and possibly by the production of organic compounds synthesised from atmospheric NH3, indicates that NH3 which enters leaves is rapidly assimilated if photosynthesis or photorespiration provide nitrogen acceptor molecules.This work was supported by the Biotechnology and Biological Sciences Research Council and the Deutsche Forschungsgemein-schaft within the framework of the research of Sonderforschun-gsbreich 251 of the University of Würzburg. We are grateful to Dr. B. Wollenweber (The Royal Veterinary and Agricultural University, Denmark) for discussions. 相似文献
134.
Seong-Lyul Rhim Hwa-Jin Cho Byung-Dong Kim Wolfgang Schnetter Klaus Geider 《Molecular breeding : new strategies in plant improvement》1995,1(3):229-236
A crystal -endotoxin gene ofBacillus thuringiensis subsp.tenebrionis (B.t.t.) encoding a coleopteran insect-specific toxin was used to construct a chimeric gene which expressed the toxin in plant cells. Via anAgrobacterium tumefaciens binary vector system, the toxin gene was transferred into tomato cells. From leaf disks recombinant plants were regenerated. Hybridization experiments demonstrated that these plants synthesized toxin-specific mRNA of the expected size. Transgenic tomato plants with the chimericB.t.t. toxin gene contained a 74 kDa protein which cross-reacted with toxin antibodies. The expression caused a significant insecticidal activity of the transgenic tomato plants against Colorado potato beetle larvae. 相似文献
135.
卷果涩芥(Malcolmia scorpioides)、四齿芥(Tetracme quadricornis)、长齿四齿芥(T.recurvata)和狭果鹤虱(Lappula semiglabra)为新疆北部常见的四种短命植物。本文从种子生物学、发育节律、株形和植株寿命等方面研究它们与生存环境的协调与适应。 相似文献
136.
Thomas R. Meagher 《Evolution; international journal of organic evolution》1994,48(4):939-951
A well-established theoretical relationship exists between genetic correlations between the sexes and the dynamics of response to sex-specific selection. The present study investigates the response to sex-specific selection for two sexually dimorphic traits that have been documented to be genetically variable, calyx diameter and flower number, in Silene latifolia. Following the establishment of a base generation with a known genetic background, selection lines were established and two generations of sex-specific selection were imposed. Calyx diameter responded directly to sex-specific selection, and the positive genetic correlation between the sexes was reflected in correlated responses in the sex that was not the basis for selection within a particular line. Flower number showed a more erratic response to sex-specific selection in that selection in some lines was initially in the wrong direction, that is, selection for a decrease in flower number resulted in an increase. These erratic responses were attributable to genotype-environment interaction as reflected in significant heteroscedasticity in variance among families. Correlated responses to selection in the sex that was not the immediate basis for selection indicated the possible existence of a negative genetic correlation between the sexes for this trait. These results test for the first time the impact of genetic correlations between the sexes on the evolutionary dynamics of sexually dimorphic traits in a plant species. 相似文献
137.
Plant defence systems induced by ozone 总被引:29,自引:9,他引:20
J. KANGASJÄRVI J. TALVINEN M. UTRIAINEN R. KARJALAINEN 《Plant, cell & environment》1994,17(7):783-794
Recent advances in the understanding of the molecular basis of plant response to ozone attack are reviewed. Plants grown in elevated atmospheric ozone are known to undergo several biochemical changes before any actual damage can be detected. These reactions include increases in the activities of enzymes associated with general plant defence mechanisms. Ozone exposure often causes a surge in the production of the plant hormone ethylene, as well as changes in polyamine metabolism and increases in the activities of several phenylpropanoid and flavonoid pathway enzymes. The activities of superoxide dismutase and peroxidases that protect cells from the oxidative damage caused by hydroxyl radicals, H2O2 and superoxides also increase. However, ozone-induced changes in plant cells at the gene level are almost unknown. The limited data available suggest close similarities between ozone-induced and pathogen-induced defence responses in plants. Several general defence genes that have been cloned in other studies will soon be applied to studies of gene expression in ozone-exposed plants. The use of molecular biological tools in ozone research should enable the development of highly specific and sensitive molecular markers for biomonitoring ozone-induced injuries in plants. 相似文献
138.
Leaf and shoot explants of Sempervivum tectorum L., taken from 14- and 30-day-old plants germinated in vitro, have been studied by using Murashige-Skoog and White basal media with cytokinins (benzyladenine, kinetin) and auxins (indoleacetic acid, naphthaleneacetic acid, indolebutyric acid) in various concentrations. Explants taken from 14-day-old plants died but 30-day-old leaves and shoots produced yellow and soft, as well as green and hard calluses on Murashige-Skoog medium with 4.4–8.8 M benzyladenine and 0.57 M indoleacetic acid. Shoot organogenesis was induced from green, hard callus in a medium with 2.2 M benzyladenine plus either 1.1 M indoleacetic acid or 2.5 M indolebutyric acid. Whole plants were grown on Murashige-Skoog medium without plant growth regulators. On the other hand, White medium was not suitable for raising Sempervivum tectorum in vitro.Abbreviations BA
benzyladenine
- IAA
indoleacetic acid
- IBA
indolebutyric acid
- MS
Murashige-Skoog
- NAA
napthaleneacetic acid
- W
White 相似文献
139.
140.
Ion channels are found in most plant membranes. They catalyse the rapid passive uniport of particular ions with varying selectivity. Planar lipid-bilayer (PLB) techniques have been developed to study the electrical activities of single ion channels in well-defined lipid and aqueous environments. They greatly facilitate both the biophysical and biochemical characterisation of ion channels and complement both conventional impaling electrode and membrane-patch voltage-clamping (patch-clamping) electrophysiological techniques applied in vivo. Bilayers can be formed across the end of patch-clamp pipettes or across apertures in specifically designed chambers. Ion channels in native membranes and purified, genetically altered or synthetic ion channels, proteins and peptides can all be studied in PLBs. The main applications of PLBs are (1) to study ion channels in membranes inaccessible to patch-clamp electrodes, (2) to provide a functional assay system during channel-protein purification and (3) to investigate the relationship between the molecular structure of ion channels and their conductance properties. In the present article we describe the techniques available for reconstitution and analysis of ion channels in PLBs and discuss how the PLB technique has been, and may be, useful to the study of plant ion channels. 相似文献