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1.
The effect of cadmium on growth and contents of glutathione (GSH) and phytochelatins (PCs) were investigated in roots and
leaves of tomato plants (Lycopersicon esculentum Mill. cv. 63/5 F1). The accumulation of Cd increased with external Cd concentrations and was considerably higher in roots
than in leaves. Dry mass production decreased under Cd treatment especially in leaves. In both roots and leaves, exposure
to Cd caused an appreciable decline in GSH contents and increase in PCs synthesis proportional to Cd concentrations in the
growth medium. At the same Cd concentration, PCs production was higher in roots than in leaves. The implication of glutathione
in PC synthesis was strongly suggested by the use of buthionine sulfoximine (BSO). The major fraction of Cd accumulated by
tomato roots was in the form of a Cd-PCs complex. 相似文献
2.
Hydrated thalli of the lichen Lobaria pulmonaria were either preconditioned to dim irradiance (DI, 5 μmol m−2 s−1) or medium irradiance (MI, 200 μmol m−2 s−1) for 6 h. After this 6 h period, the thalli were allowed to desiccate under the two respective irradiances. Thereafter, these
dry lichens were exposed to high irradiance (HI, 1 000 μmol m−2 s−1) for 60 h. After this HI treatment, the maximal photochemical quantum yield (FV/FM) and the de-epoxidation state of xanthophyll cycle pigments (DEPS) were highest in thalli preconditioned to MI. Hence irradiance
in the last hydrated period before sampling is significant for the physiological state of lichens. A standardized irradiance
pre-treatment before start of experiments is recommended. 相似文献
3.
The effects of salinity on growth, leaf nutrient content, water relations, gas exchange parameters and chlorophyll fluorescence
were studied in six-month-old seedlings of citrus (Citrus limonia Osbeck) and rooted cuttings of olive (Olea europaea L. cv. Arbequina). Citrus and olive were grown in a greenhouse and watered with half strength Hoagland’s solution plus 0
or 50 mM NaCl for citrus, or plus 0 or 100 mM NaCl for olive. Salinity increased Cl− and Na+ content in leaves and roots in both species and reduced total plant dry mass, net photosynthetic rate and stomatal conductance.
Decreased growth and gas exchange was apparently due to a toxic effect of Cl− and/or Na+ and not due to osmotic stress since both species were able to osmotically adjust to maintain pressure potential higher than
in non-salinized leaves. Internal CO2 concentration in the mesophyll was not reduced in either species. Salinity decreased leaf chlorophyll a content only in citrus. 相似文献
4.
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
5.
The common bean (Phaseolus vulgaris L.) is sensitive to high temperature, while an ecologically contrasting species (Phaseolus acutifolius A. Gray) is cultivated successfully in hot environments. In this study, the two bean species were respectively acclimated
to a control temperature of 25 °C and a moderately elevated temperature of 35 °C in order to compare the thermotolerance capabilities
of their photosynthetic light reactions. Growth at 35 °C appeared to have no obvious adverse effect on the photosynthetic
activities of the two beans, but changed their thermotolerance. After a short period of heat shock (40 °C for up to 4 h),
the photosynthetic activities of 25 °C-grown P. vulgaris declined more severely than those of P. acutifolius grown at 25 °C, implying that the basal thermotolerance of P. vulgaris is inferior to that of P. acutifolius. But after acclimating to 35 °C, the thermotolerances of the two species were both greatly enhanced to about the same level,
clearly demonstrating the induction of acquired thermotolerance in their chloroplasts, and P. vulgaris could be as good as P. acutifolius. Temperature acclimation also changed plants’ resistance to photoinhibition in a manner similar to those toward heat stress.
In addition, acquisition of tolerance to heat and strong irradiance would reduce the dependency of the two beans on xanthophyll
pigments to dissipate heat, and also seemed irrelevant to the agents with antioxidant activities such as SOD. 相似文献
6.
In lichens, ribitol is known as a carbon storage compound, an osmotic agens involved effectively in cell compartments protection
during dehydration of lichen thalli and as a cryoprotective compound. In our study, we investigated the effect of ribitol
on photochemical processes of photosynthesis in foliose lichens [Lasallia pustulata (L.) Mérat., Umbilicaria hirsuta (Sw. ex Westr.) Hoffm.] at low temperature. The effects of three concentrations of ribitol, added externally to thalli segments
on several chlorophyll (Chl) fluorescence parameters, were evaluated. The 72 h exposition to 8, 16, and 26 mM ribitol led
to a concentration-dependent increase in FV/FM, decrease in non-photochemical quenching (NPQ) but no change in quantum yield of photosystem II photochemistry (ΦPSII) values at −5 °C). At higher temperature (0, +5 °C), no effect of ribitol addition on the photosynthetic parameters was apparent. 相似文献
7.
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
8.
9.
We report the observation of two types of changes in fluorescence spectra of LHCII at 4.2 K following intense illumination
of the sample with a spectrally narrow laser beam at wavelengths between 678 and 686 nm. Nonspecific changes (burning-wavelength
independent) are characterized by two relatively broad bands: a positive one at ∼ 678.7 nm and a negative one at ∼ 680.8 nm.
These changes reveal a ∼1.3-nm blue shift of the distribution of final emitters in LHCII, from 680.3 nm to ∼ 679.0 nm independent
of the excitation wavelength. Specific fluorescence changes (burning-wavelength dependent) are characterized by a sharp hole
exactly at the burning wavelength, and positive changes directly to the shorter-and longer-wavelength side of the narrow hole.
The negative changes are interpreted as zero-phonon holes, while the positive features are assigned to non-photochemical products.
In the low-burning intensity experiment, in addition to the zero-phonon holes, we observed also the holes to the longer wavelength
of the zero-phonon hole, which were assigned to a sum of phonon and pseudo-phonon side bands. The shapes of these extra holes
are identical to the shapes of the holes revealed in the fluorescence line narrowing experiment. On the basis of the low-burning
intensity experiment we estimated the upper limit of the electron-phonon coupling strength for LHCII, characterized by a Huang-Rhys
factor of 1.5. 相似文献
10.
Treatment of tomato seedlings (Lycopersicon esculentum Mill. cv. 63/5 F1) with increasing CdCl2 concentrations in the culture medium resulted in Cd accumulation more important in roots than in leaves. Biomass production
was severely inhibited, even at low Cd concentration. Cd reduced chlorophyll content in leaves and enhanced lipid peroxidation.
An increase in antioxidative enzyme (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase)
activities was more pronounced in leaves than in roots, while catalase activity increased only in roots. In addition, changes
in isoenzyme composition were observed using the non-denaturing polyacrylamid gel electrophoresis. 相似文献
11.
Ethylene production and growth of callus cultures of lavandin (Lavandula offidnalis Cham x Lavandula latifolia Villars) cv.
Grosso were examined. Callus lines, derived from various kinds of primary expiants (shoot tip, leaf and calyx), exhibited
differences in ethylene production patterns independent of callus growth. Moreover these differences could not be ascribed
to the expiant source. Within a line, ethylene pattern paralleled callus growth curve. Variations in ethylene evolution were
induced in shoot tip callus by means of ACC, AVG and varied amounts of 2,4-D in the culture medium. Following all these treatments
callus growth was not altered. Hie decrease in 2,4-D concentration caused changes in Chl a and water content of the tissues. 相似文献
12.
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
13.
In transgenic (TG) tomato (Lycopersicon esculentum Mill.) overexpressed ω-3 fatty acid desaturase gene (LeFAD7) was identified, which was controlled by the cauliflower mosaic virus 35S promoter and induced increased contents of unsaturated
fatty acids in thylakoid membrane. Under chilling stress at low irradiance (4 °C, 100 μmol m−2 s−1) TG plants with higher linolenic acids (18: 3) content maintained a higher O2 evolution rate, oxidizable P700 content, and maximal photochemical efficiency (Fv/Fm) than wild type (WT) plants. Low temperature treatment for 6 h resulted in extensive changes of chloroplast ultrastructure:
in WT plants most chloroplasts became circular, the number of amyloids increased, appressed granum stacks were dissolved,
grana disappeared, and the number of grana decreased, while only a few grana were found in leaves of TG plants. Hence the
overexpression of LeFAD7 could increase the content of 18: 3 in thylakoid membrane, and this increase alleviated the photoinhibition of photosystem
(PS) 1 and PS2 under chilling at low irradiance. 相似文献
14.
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
15.
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
16.
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
17.
18.
In 7-d-old seedlings of Brassica juncea chromium (VI) promoted photosystem 2 (PS 2) mediated photoreactions. The increase in PS 2 activity in the thylakoids from
Cr-treated seedlings, in the presence of uncoupler (5 mM NH4Cl), was similar to that recorded with the control thylakoids. Thus Cr enhanced PS 2 activity was not due to uncoupling of
electron transport from photophosphorylation. Photon saturation kinetics revealed that the PS 2 activity of thylakoids from
Cr-treated seedlings was significantly higher at almost all irradiances in comparison to that of controls. PS 2 activity of
thylakoids from Cr-treated plants at 25 % of the saturating irradiance was in par with the PS 2 activity of the thylakoids from control plants at saturating irradiance. Thylakoids from both control and Cr-treated
seedlings exhibited maximum PS 2 activity at pH 7.5. The PS 2 activity of thylakoids from Cr-treated plants remained high
even at pH 8.0 and 8.5, demonstrating Cr enhances tolerance of PS 2 to alkaline pH. 相似文献
19.
20.
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