共查询到20条相似文献,搜索用时 9 毫秒
1.
Germination of lupine (Lupinus luteus L.) seeds was accompanied by an increase in concentration of free radicals with g
1
and g
2
values of 2.0056 ± 0.0003 and 2.0033 ± 0.0005, respectively. The highest intensity of free radical signal was observed in
embryo axes immediately after radicle protruded through the seed coat. Hydrogen peroxide accumulated in embryonic axes and
cotyledons during imbibition before the onset of germination in the seed population. The activities of superoxide dismutase
(SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) rose progressively in embryo axes. In cotyledons SOD activity did not change
significantly, while that of CAT increased during germination. The enhancement of Cu, Zn-SODs and Mn-SOD isoforms in embryonic
axes was observed. A new isoform of catalase was synthesized, suggesting that it plays a relevant role during germination.
SOD and CAT activities were detected in dry seeds. Free radical generation and response of antioxidative enzymes differed
between embryo axes and cotyledons during the germination timecourse. 相似文献
2.
The pattern of the activity of arginine decarboxylase (ADC) and omithine decarboxylase (ODC) involved in polyamine synthesis
in ripening wheat seeds was examined. The aim was to study the polyamines and the activity of the two enzymes in correlation
with the growth processes occurring in the developing wheat seeds. The results obtained showed a very different pattern of
polyamine content in the two organs of caryopsis, and that the two enzymes in the embryos have a higher activity than in the
endosperms. Moreover, while in the embryos the ADC exhibits higher activity than the ODC, in the endosperms the activity of
ODC is about similar to that of ADC. This pattern is discussed in relation to the different histological characteristics of
embryo and endosperm tissues during seed development. 相似文献
3.
Peroxidase activity (EC 1.11.1.7) towards phenolic substrates, i.e. pyrogallol, syringaldazine and guaiacol, and ascorbate peroxidase activity (EC 1.11.1.11) were analyzed in embryo axes of Lupinus luteus L. cv. Polo cultured on Heller medium for 96h after inoculation with the necrotrophic fungus Fusarium oxysporum f.sp. Schlecht lupini. Four variants were compared: inoculated embryo axes cultured with 60mM sucrose (+Si) or without it (-Si), and non-inoculated embryo axes cultured with 60mM sucrose (+Sn) or without it (-Sn). Between 0 and 96h of culture, peroxidase activity towards the phenolic substrates increased in all variants except -Si, where a decrease was noted in peroxidase activity towards syringaldazine and guaiacol, but not towards pyrogallol. In +Si tissues, a considerable increase in enzyme activity towards these substrates was recorded starting from 72h of culture. Lignin content of +Si tissues increased already at the first stage of infection, i.e. 24h after inoculation. Additionally, in +Sn tissues, high ascorbate peroxidase activity was observed during the culture. Its activity increased in +Si tissues, beginning at 72h after inoculation. However, this was lower than in +Sn tissues. At 72h after inoculation, a considerably stronger development of the infection was observed in -Si than in +Si tissues during our earlier research [Morkunas, I. et al., 2005. Sucrose-stimulated accumulation of isoflavonoids as a defense response of lupine to Fusarium oxysporum. Plant Physiol Biochem 2005; 43: 363-73]. Both peroxidases assayed towards phenolic substrates and ascorbate peroxidase was less active in -Si tissues than in -Sn tissues. Hydrogen peroxide concentration was much higher in -Si than in +Si tissues. These results indicate that peroxidases may be some of the elements of the defense system that are stimulated by sucrose in yellow lupine embryo axes in response to infection caused by F. oxysporum. 相似文献
4.
Rapid mobilisation of storage products, including xyloglucan, in cotyledons of germinating nasturtium (Tropaeolum majus L.) normally starts about 7–8 d after imbibition and growth of the seedling at 20–25° C. Levels of activity of endo-1,4--glucanase (EC 3.2.1.4) in cotyledons, as assayed viscometrically with xyloglucan as substrate, varied in parallel with the rate of breakdown of xyloglucan. When cotyledons were excised from the seedling axis and incubated on moist filter paper at any point before 7 d, the catabolic reactions which normally occurred in the intact seedling were suspended. If, however, cotyledons excised at 8 d were incubated in 10–6 M 2,4-dichlorophenoxyacetic acid, a rise in endo-1,4--glucanase (xyloglucanase) activity was observed and a sharp decrease in fresh and dry weight as well as xyloglucan levels ensued at rates comparable to those observed in cotyledons attached to the seedling. Neither gibberellin nor kinetin treatments promoted xyloglucan breakdown or enhanced xyloglucanase activity. Addition of auxin to excised cotyledons before 7 d did not evoke premature breakdown, indicating that the tissue became receptive to auxin only at this time. The triggering process took place in darkness and was unaffected by various light-dark cycles. It is concluded that the sudden degradation of xyloglucan which occurs in nasturtium seeds about a week after germination begins is the result of enhanced activity of a depolymerizing xyloglucanase, this activity being evoked by auxin originating in the emerging seedling axis.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- 2,3-D
2,3-dichlorophenoxyacetic acid
- GA3
gibberellic acid
- kDa
kilodalton
The authors are pleased to acknowledge the technical assistance of Alexander Marcus and valuable discussions with Dr. Vladimir Farkas. This study was supported by a scholarship to A.H. from the Deutsche Forschungsgemeinschaft (FRG) and a grant to G.M. from the Natural Sciences and Engineering Research Council of Canada. 相似文献
5.
6.
The effects of 28-homobrassinolide (HBL) on nickel uptake, protein content and activities of antioxidative enzymes were determined
in the seedlings of Brassica juncea L. The seeds were treated with different concentrations (0, 0.01, 1 and 100 nM) of HBL for 8 h and then sown in the Petri
plates containing various concentrations (0, 25, 50 and 100 mg dm−3) of nickel. After 7 d, observations were made on shoot and root length, Ni uptake, protein content and activities of antioxidative
enzymes (guaiacol peroxidase, catalase, glutathione reductase, ascorbate peroxidase and superoxide dismutase). The growth
of seedlings was inhibited by Ni, however, less after HBL pre-treatment. The protein content and antioxidative enzyme activities
were also increased by HBL treatment. 相似文献
7.
Fusarium oxysporum-induced oxidative stress and antioxidative defenses of yellow lupine embryo axes with different sugar levels 总被引:1,自引:0,他引:1
This study was designed to investigate whether and to what extent oxidative stress is induced in embryo axes of Lupinus luteus L. cv. Polo inoculated with a necrotrophic fungus, Fusarium oxysporum and cultured on Heller medium for 96h. Four variants were compared: inoculated embryo axes cultured with 60mM sucrose (+Si) or without it (-Si), and non-inoculated embryo axes cultured with 60mM sucrose (+Sn) or without it (-Sn). After inoculation, an accumulation of stable free radicals and Mn2+ ions in +Si and -Si were detected by electron paramagnetic resonance. Concentrations of the radicals with g-values of 2.0052+/-0.0004 and 2.0029+/-0.0003 were generally higher in -Si than in +Si. Beginning at 24h after inoculation, in both +Si and -Si the concentrations of these ions decreased, but more strongly in -Si than in +Si. After inoculation, the activities of superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) were higher in -Si than in +Si. SOD and CAT zymograms showed that the synthesis of new isoforms was induced after inoculation. Simultaneously, superoxide anions were assayed in embryo axes by using their specific indicator dihydroethidium (DHE). The DHE-derived fluorescence was stronger and covered a much larger tissue area in +Si than in -Si. The respiration rate was generally much higher in +Si than in -Si. Electron micrographs revealed that, in contrast to -Si cells, +Si cells had numerous mitochondria with less reduced numbers of cristae and long sections of rough endoplasmic reticulum and Golgi bodies. These results indicate that different defensive strategies against F. oxysporum were induced depending on soluble sugar levels in yellow lupine embryo axes. 相似文献
8.
Somatic embryos differentiated from hypocotyl explant in cotton (Gossypium hirsutum L.) exhibited very divergent morphologies. Six different types of somatic embryos based on cotyledon development were observed.
The growth hormones (2,4-dichlorophenoxyacetic acid and kinetin) used in induction and maintenance media did not affect embryo
rooting and germination. The 95 % conversion of normal embryos (with two cotyledons) was achieved, while an overall conversion
was only 38 %. Horn shaped embryos failed to exhibit shoot growth. Poorly developed apical meristems were responsible for
lower conversion percentages in some of embryo classes. However, regenerated plants phenotypically resembled to seed grown
control plants regardless of somatic embryo morphology. 相似文献
9.
The intensity of protein reserve activation in yellow lupine (Lupinus luteus L.) organs cultured in vitro in the presence of saccharose and without sugar in the medium was studied. Isolated embryo axes, excised cotyledons and seeds
deprived of their testae were grown on Heller medium: a) with 60 mM saccharose (+S), b) without sugar (−S) and c) for 72 hours
without saccharose + for 24 hours in the presence of saccharose (−S→+S). Using nitroanilide substrates, exo- and endopeptidase
proteolytic activity was investigated in enzymatic extracts. Proteolytic activity was examined in organs isolated from swollen
seeds and also in organs cultured for 24, 48, 72 and 96 hours. The proteolytic activity was higher in organs cultured on medium
without saccharose. Stimulation of the proteolytic activity on the first day of culture was not significant, but intensified
in the successive days of culture. The organ subcultured onto a medium with saccharose (−S→+S) caused a significant limitation
of proteolytic activity, even to a markedly lower level in comparison to that activity level in the material continuously
supplemented with saccharose. Observations of ultrastructure in Transmission Electron Microscopy revealed increased protein
body degradation in the absence of saccharose in the medium and an increased degree of cell vacuolization, which may be indicative
of intensifying autophagic processes under conditions of carbohydrate deficit. 相似文献
10.
A. I. Cordeiro J. F. Sanchez-Sevilla M. C. Alvarez-Tinaut M. C. Gomez-Jimenez 《Biologia Plantarum》2008,52(4):642-647
Eighty seven olive (Olea europaea ssp. sativa L.) cultivar accessions from Portugal were characterized by means of randomly amplified polymorphic DNA (RAPD) markers. Of
the 11 arbitrary 10-mer primers tested a total of 92 polymorphic bands were obtained, representing 87.6 % of the total amplification
products. Twenty nine different genotypes were clearly discriminated. Differences were not found among the amplification profiles
from different individuals of the same cultivar. All the genotypes could be identified by the combination of three primers:
OPR-1, OPK-14 and OPA-1, seven genotype-specific markers being detected. Genetic relationships were estimated by the unweighted
pair-group method with arithmetic averaging (UPGMA). The genetic analysis of the results showed a gradual distance between
the various cultivars, making it difficult to identify well-differentiated phylogenetic groups, although two clusters were
distinguishable with 35 % similarity, in addition to three independent branches with lower similarity: Galega, Tentilheira
and Redondal. The dendrogram reflect some relationships for most of the cultivars according to the use of the fruit and ecological
adaptation. 相似文献
11.
We have investigated the effects of cadmium on the microtubular (MT) cytoskeleton in the root tip cells of Allium sativum L. using indirect immunofluorescence microscopy. Cd affected the mechanisms controlling the organization of MT cytoskeleton,
as well as tubulin assembly/disassembly processes. Cd induced the formation of abnormal MT arrays, consisting of discontinuous
wavy MTs or short MT fragments at the cell periphery. Cadmium caused irregular nuclear disorder in cells where the MT organization
and function was disturbed. Furthermore, with increased Cd concentration and duration of treatment the MTs depolymerized more
severely, the frequency of abnormal cell increased and the mitotic index decreased progressively. The above findings showed
that MT cytoskeleton is one of target sites of Cd toxicity in root tip cells. 相似文献
12.
The effect of ethylenediurea (EDU) was tested using the chlorophyll (Chl) a fluorescence transient analysis, performed with JIP-test, to assess ambient ozone (O3) effects on photosynthesis of adult trees under natural conditions. Twelve adult European ash (Fraxinus excelsior L.) trees, known to be sensitive or tolerant to O3, determined by presence symptomatic (S) or absence asymptomatic (AS) trees of foliar symptoms in previous years, were treated
either with distilled water containing 450 g m−3 EDU or with distilled water. Once a month across the growing season [the accumulated exposure over a threshold of 40 nmol(O3) mol−1 was 32.49 μmol mol−1 h−1], Chl a fluorescence transients were measured in vivo on dark-adapted leaves of 1-year-old labeled shoots, from the lower crown part. Twenty-five parameters were calculated. The
maximum quantum yield of primary photochemistry (ϕPo or Fv/Fm) did not differentiate between S-and AS-trees, while increased Chl content and de-excitation rates suggested compensation
of O3 injury in S-trees. Seasonal reductions in absorbing fluxes and increase in heat and fluorescence dissipation processes was
due to leaf ageing and drought, the latter suggesting water deficit influenced Chl a fluorescence stronger than ambient O3 exposure. AS-trees showed elevated probability of connectivity among photosystem 2 units, a mechanism to stimulate energy
dissipation and reduce photo-oxidative injury. EDU prevented the inactivation of reaction centers. This slight effect does
not warrant EDU as a tool to assess O3 effects on photosynthesis, while the JIP-test is suggested for a quantitative assessment in adult trees. 相似文献
13.
One of the least understood enzymatic steps in chlorophyll biosynthesis is the formation of isocyclic ring, which is catalyzed
by the Mg-protoporphyrin IX monomethyl ester (MgPME) cyclase that is involved in the conversion of MgPME to protochlorophyllide.
Several genes encoding part of this enzyme have been identified and functional analysis of them has been performed. The enzyme
plays important roles in higher plants and photosynthetic bacteria. The review focuses on the current knowledge of MgPME cyclase
coding genes, with emphasis on their organization, expression pattern, and functional analysis obtained from mutants. 相似文献
14.
The chlorophyll fluorescence (F) temperature curves in a linear time-temperature heating/cooling regime were used to study
heat-induced irreversible F changes in primary green leaves of spring barley (Hordeum vulgare L. cv. Akcent). The leaf segments were heated in a stirred water bath at heating rates of 0.0083, 0.0166, 0.0333, and 0.0500
°C s−1 from room temperature up to maximal temperature T
m and then linearly cooled to 35 °C at the same rate. The F intensity was measured by a pulse-modulated technique. The results
support the existence of the two critical temperatures of irreversible F changes postulated earlier, at 45–48 and 53–55 °C.
The critical temperatures are slightly dependent on the heating rate. Two types of parameters were used to characterize the
irreversibility of the F changes: the coefficient of irreversibility μ defined as the ratio of F intensity at 35 °C at the
starting/ending parts of the cycle and the slopes of tangents of linear parts of the F temperature curve. The dependence of
μ on T
m revealed a maximum, which moved from 54 to 61 °C with the increasing heating/cooling rate v from 0.0083 to 0.0500 °C s−1, showing two basic phases of the irreversible changes. The Arrhenius and Eyring approaches were applied to calculate the
activation energies of the initial increase in μ. The values varied between 30 and 50 kJ mol−1 and decreased slightly with the increasing heating rate. 相似文献
15.
In this study, Dendrobium Sonia 17 plantlets were used to induce in vitro flowering. Inflorescences were induced and rooting was inhibited in the half-strength Murashige and Skoog medium containing
20 μM N
6-benzyladenine (BA). The medium with high P and low N contents was effective to induce inflorescences while the medium with
low P and high N contents was only effective to promote forming of shoots. In addition, the induced in vitro inflorescences were able to multiply and maintain without exhibiting a distinctive vegetative phase. Different morphologies
of in vitro flowers such as incomplete flower structures, abnormal and unresupinated in vitro flowers were observed. 相似文献
16.
Modelling the dynamics of the electron transport rate measured by PAM fluorimetry during Rapid Light Curve experiments 总被引:1,自引:0,他引:1
We propose a dynamic model specifically designed to simulate changes in the photosynthetic electron transport rate, which
is calculated from fluorescence measurements when plants are exposed, for a short time, to a series of increasing photon flux
densities. This model simulates the dynamics of the effective yield of photochemical energy conversion from the maximum and
natural chlorophyll fluorescence yields, taking into account a cumulative effect of successive irradiations on photosystems.
To estimate a characteristic time of this effect on photosystems, two series of experiments were performed on two benthic
diatom culture concentrations. For each concentration, two different series of irradiations were applied. Simplified formulations
of the model were established based on the observed fluorescence curves. The simplified versions of the model streamlined
the parameters estimation procedure. For the most simplified version of the model (only 4 parameters) the order of magnitude
of the characteristic time of the residual effect of irradiation was about 38 s (within a confidence interval between 20 and
252 s). The model and an appropriate calibration procedure may be used to assess the physiological condition of plants experiencing
short time-scale irradiance changes in experimental or field conditions. 相似文献
17.
A glutathione S-transferase (GST) gene cloned from the lepidopteran spruce budworm, Choristoneura fumiferana Clem. was transformed into the model plant Arabidopsis thaliana. The CfGST-transgenic and wild-type A. thaliana were subjected to 4 and 10 °C for 48 h and their cold resistance was studied. The GST activity of the transgenic plants was
46.6 and 35.7 % higher than that of the wild-type plants after 48 h under 4 and 10 °C, respectively. Relative membrane permeability
and malondialdehyde content in the transgenic plants were lower while contents of the chlorophyll and proline were higher
than those in the wild-type plants under 4 and 10 °C. The survival rate of the transgenic plants was 43.7 % for 24 h under
0 °C, while survival rate of wild-type plants was 28.3 %. The results indicated that the insect GST could enhance cold resistance
in the transgenic A. thaliana. 相似文献
18.
Hybrids including Hystrix patula, H. duthiei and H. longearistata were obtained and genetic relationships among them were studied. Meiotic pairing in hybrids of H. duthiei × Psathyrostachys juncea (Ns), H. longearistata × Psa. juncea (Ns), Leymus multicaulis (NsXm) × H. duthiei, L. multicaulis (NsXm) × H. longearistata, Elymus sibiricus (StH) × H. patula, Roegneria ciliaris (StY) × H. patula, R. ciliaris (StY) × H. duthiei and R. ciliaris (StY) × H. longearistata averaged 5.76, 5.44, 11.94, 10.88, 10.08, 3.57, 0.46 and 0.90 bivalents per cell, respectively. The results indicated that
H. duthiei and H. longearistata had the NsXm genomes of Leymus, while H. patula contained the StH genomes and had a low genome affinity with the StY genomes of Roegneria. Results of genome-specific RAPD assay were comparable with the chromosome pairing data. According to the genomic system
of classification in Triticeae, H. patula should be considered as Elymus hystrix L., while H. duthiei and H. longearistata as Leymus duthiei and Leymus duthiei ssp. longearistata, respectively. 相似文献
19.
C. -W. Zhu J. -G. Zhu G. Liu Q. Zeng Z. -B. Xie J. Pang Z. -Z. Feng H. -Y. Tang L. Wang 《Photosynthetica》2008,46(2):318-320
Net photosynthetic rate (P
N) of ear and flag leaf during grain filling stage and grain yield of plants with non-darkened or darkened flag leaf or darkened
ear were examined in two different CO2 concentrations: ambient (AC) and AC+200 μmol mol−1 (EC). Ear showed much higher enhancement (56 %) of P
N than flag leaf (23 %) under EC. Moreover, CO2 enrichment shortened the photosynthetic duration of flag leaf relative to ear. In this way the ratio of ear to flag leaf
contribution to grain yield increased from 1.18 (AC) to 1.39 (EC). 相似文献
20.
We quantified inbreeding depression for fruit production, embryo vitality and seed germination in three deceptive orchids,
Serapias vomeracea, S. cordigera and S. parviflora, which do not provide any reward to their pollinators, and are predicted to experience high outcrossing. Of the three species
examined only S. parviflora was autonomously selfing. Both S. vomeracea and S. cordigera showed highly significant differences in fitness between selfed and outcrossed progenies, resulting in high levels of inbreeding
depression, which increased in magnitude from seed set to seed germination. Inbreeding depression may promote outcrossing
in Serapias by acting as a post-pollination barrier to selfing. Cumulative inbreeding depression across three stages in S. parviflora was lower that in both outcrossing species. The large difference in germination between selfed and outcrossed seeds is an
important issue in conservation biology. 相似文献