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1.
Distribution of small roots (diameter between 2 mm and 5 mm) was studied in 19 pits with a total of 72 m2 trench profile walls in pure stands of Fagus sylvatica and Picea abies. Root positions within the walls were marked and transformed into x-coordinates and y-coordinates. In a GIS-based evaluation, zones of potential influence around each root were calculated. The total potential
influence produced isoline maps of relative root influence zones, thus indicating small root clustering. The questions studied
were (1) whether there were marked clusters of small roots in the soil and (2) whether trees surrounding the pit (defined
as tree density) correlate with the root abundance and distribution on the trench profile walls. Small roots of both species
showed maximum abundance in the top 20 cm of the soil, where pronounced root clusters occurred next to areas with only low
root accumulation. The area of root clusters did not differ significantly between the two stands. Weighted clumping, WC, calculated
as a product of root class, and its area was used as an index of root clustering, which again did not differ between beech
and spruce stands. However, evaluations on a single root level showed that beech achieved the same degree of clustering with
lower number of roots. Regardless of soil properties related to root clusters, a significantly higher clustering acquired
per root for beech than for spruce suggests beech to be more efficient in belowground acquisition of space. Because none of
the parameters describing root clustering were correlated with tree density around the investigated soil profiles, clusters
of small roots are inherently present within the tree stands. 相似文献
2.
Phytochelatins (PCs) are post-translationally synthesized thiol reactive peptides that play important roles in detoxification
of heavy metal and metalloids in plants and other living organisms. The overall goal of this study is to develop transgenic
plants with increased tolerance for and accumulation of heavy metals and metalloids from soil by expressing an Arabidopsis
thaliana
AtPCS1 gene, encoding phytochelatin synthase (PCS), in Indian mustard (Brassica juncea L.). A FLAG-tagged AtPCS1 gDNA, under its native promoter, is expressed in Indian mustard, and transgenic pcs lines have been compared with wild-type
plants for tolerance to and accumulation of cadmium (Cd) and arsenic (As). Compared to wild type plants, transgenic plants
exhibit significantly higher tolerance to Cd and As. Shoots of Cd-treated pcs plants have significantly higher concentrations
of PCs and thiols than those of wild-type plants. Shoots of wild-type plants accumulated significantly more Cd than those
of transgenic plants, while accumulation of As in transgenic plants was similar to that in wild type plants. Although phytochelatin
synthase improves the ability of Indian mustard to tolerate higher levels of the heavy metal Cd and the metalloid As, it does
not increase the accumulation potential of these metals in the above ground tissues of Indian mustard plants. 相似文献
3.
The physiological responses to NaCl salinity were investigated in two floating aquatic macrophytes, Pistia stratiotes L. and Salvinia molesta L. With the increasing NaCl concentration a decrease in chlorophyll and carotenoid contents was recorded in Salvinia as compared to Pistia. Also a greater increase in H2O2 accumulation and lipid peroxidation was observed in the shoot and root tissues of Salvinia as compared to Pistia. The superoxide dismutase, glutathione reductase, catalase and guaiacol peroxidase activities, and ascorbate and glutathione contents increased in Salvinia and Pistia shoot and root tissues in response to NaCl. 相似文献
4.
Sazada Siddiqui Mukesh K. Meghvansi Mushtaq A. Wani Farah Jabee 《Acta Physiologiae Plantarum》2009,31(3):531-536
The effect of cadmium (Cd) was studied on root tips of Pisum sativum L. Seeds of P.
sativum were treated with a series of concentrations ranging from 0.125, 0.250, 0.500 and 1.000 mM for 6 h. The effect of Cd was
analyzed by studying the percentage seed germination, radicle length (RL), mitotic index (MI) and chromosomal aberrations
(CAs) in root tip. The results revealed that Cd had significant impeding effect on the root meristem activity of P.
sativum at 0.500 and 1.000 mM as noticed by reduction in seed germination percentage and RL compared to control. Furthermore, it
also reduced MI in dose-related manner compared to control. Additionally, the variation in the percentage of mitotic abnormalities
was observed. The overall percentage of aberrations generally increased with increasing concentrations of Cd. Among these
abnormalities laggards, bridges, stickiness, precocious separation and fragments were most common. The obtained results demonstrated
that the Cd treatment leads to a significant reduction in MI and increase in CAs. Overall results allow us to suggest that
the Cd has clastogenic effect on the crop. 相似文献
5.
Zuzana Vatehová Karin Kollárová Ivan Zelko Danica Richterová-Kučerová Marek Bujdoš Desana Lišková 《Biologia》2012,67(3):498-504
The objective of this study was to determine the effect of silicon (Si) and cadmium (Cd) on root and shoot growth and Cd uptake
in two hydroponically cultivated Brassica species (B. juncea (L.) Czern. cv. Vitasso and B. napus L. cv. Atlantic). Both species are potentially usable for phytoextraction. Inhibitory effects of Cd on root elongation were
diminished by the impact of Si. Primary roots elongation in the presence of Cd + Si compared with Cd was stronger and the
number of lateral roots was lower in B. juncea than in B. napus. Cd content per plant was higher in B. napus roots and shoots compared with B. juncea. Suberin lamellae were formed closer to the root apex in Cd + Si than in Cd treated plants and this effect was stronger in
B. napus than in B. juncea. Accelerated maturation of endodermis was associated with reduced Cd uptake. Cd decreased the content of chlorophylls and
carotenoids in both species, but Si addition positively influenced the content of photosynthetic pigments which was higher
in B. napus than in B. juncea. Si enhanced more substantially translocation of Cd into the shoot of B. napus than of B. juncea. Based on our results B. napus seems to be more suitable for Cd phytoextraction than B. juncea because these plants produce more biomass and accumulate
higher amount of Cd. The protective effect of Si on Cd treated Brassica plants could be attributed to more extensive development of suberin lamellae in endodermis. 相似文献
6.
It has been proposed that organic acid and nonprotein thiol are involved in the hyperaccumulation of metals. In this study,
Cd accumulation, organic acid, and nonprotein thiol production and their relationships in the leaves of Cd-hyperaccumulator
Rorippa globosa were examined and compared with a closely related species, Rorippa islandica. The results showed that there was no reduction in biomass of R. globosa when treated with 25 μg Cd g−1 (T2), despite Cd accumulation in the leaves was up to 158.2 μg g−1 DW. On the other hand, the growth of Cd-treated R. islandica was obviously inhibited as it accumulated more than 100 μg g−1 DW in the leaves. Therefore, R. islandica behaved as a Cd-accumulating plant. The Cd treatments could significantly induce the synthesis of acetic acid in both species,
suggesting that acetic acid, as the most abundant organic acid, might be related to the Cd accumulation. Significant positive
correlations between Cd concentrations and both tartaric and malic acid concentrations in the leaves of R. globosa were observed. There was a significant positive correlation between Cd concentrations and acetic acid concentrations in the
leaves of R. islandica. This trend of tartaric and malic acids in the leaves of R. globosa and acetic acid in the leaves of R. islandica might be related to Cd accumulation. In addition, a quadratic relationship was obviously observed for NP-SH contents and
total Cd concentrations in the leaves of R. globosa, indicating that NP-SH was significantly related to Cd accumulation and tolerance. 相似文献
7.
Meyer CL Peisker D Courbot M Craciun AR Cazalé AC Desgain D Schat H Clemens S Verbruggen N 《Planta》2011,234(1):83-95
The synthesis of phytochelatins (PC) represents a major metal and metalloid detoxification mechanism in various species. PC
most likely play a role in the distribution and accumulation of Cd and possibly other metals. However, to date, no studies
have investigated the phytochelatin synthase (PCS) genes and their expression in the Cd-hyperaccumulating species. We used functional screens in two yeast species to identify
genes expressed by two Cd hyperaccumulators (Arabidopsis halleri and Thlaspi caerulescens) and involved in cellular Cd tolerance. As a result of these screens, PCS genes were identified for both species. PCS1 was in each case the dominating cDNA isolated. The deduced sequences of AhPCS1 and TcPCS1 are very similar to AtPCS1 and
their identity is particularly high in the proposed catalytic N-terminal domain. We also identified in A. halleri and T. caerulescens orthologues of AtPCS2 that encode functional PCS. As compared to A. halleri and A. thaliana, T. caerulescens showed the lowest PCS expression. Furthermore, concentrations of PC in Cd-treated roots were the highest in A. thaliana, intermediate in A.
halleri and the lowest in T. caerulescens. This mirrors the known capacity of these species to translocate Cd to the shoot, with T. caerulescens being the best translocator. Very low or undetectable concentrations of PC were measured in A. halleri and T. caerulescens shoots, contrary to A. thaliana. These results suggest that extremely efficient alternative Cd sequestration pathways in leaves of Cd hyperaccumulators prevent
activation of PC synthase by Cd2+ ions. 相似文献
8.
The effect of excessive Cd on the growth and metal uptake by leafy vegetables Brassica chinensis L. (cv. Wuyueman) and Brassica pekinensis (Lour.) Rupr. (cv. Qingyan 87-114) were studied in hydroponic solution culture. The Cd concentration higher than 10 μM significantly
decreased the root elongation and leaf chlorophyll contents of both plant species. The shoots of B. pekinensis had significantly higher concentrations of total and water-soluble Cd than B. chinensis. The roots of both species accumulated more Cd than the shoots in all the Cd treatments. Most of the Cd in the roots was
found in the cell walls. The shoot/root ratio of Cd concentrations in B. pekinensis was always greater than that in B. chinensis. But, the concentration and proportion of Cd in the cell walls in B. chinensis were higher than that in B. pekinensis. Cadmium treatments also increased the concentrations of total non-protein thiols (NPT) in the shoots of the both species.
A significant correlation was found between the concentrations of soluble Cd and NPT in plant shoots. 相似文献
9.
Herbaceous Echinochloa crusgalli var. frumentacea is highly resistant to a wide range of heavy metal concentrations. However, its detoxification mechanism has not been reported
yet. We exposed plants to 100 μM CdCl2 for 7 days then examined cadmium accumulation and its subcellular distribution in binding to ligands. Cd concentration increased
over the exposure period to a saturation point at day 5 when its level reached 1,732.41 μg g−1 dry weight, an amount about 820 times greater than that found in the control. In the roots, most Cd was distributed in the
insoluble fraction, perhaps because of an absorption mechanism at the root surface. Our profile for distribution revealed
two Cd-binding ligand peaks: a high molecular weight of 60 kDa and a 2.5-kDa Cd-binding ligand. The latter increased with
time and had a typical phytochelatin (PC) amino acid composition of predominantly cysteine, glutamate, and glycine (16.5%,
16.6%, and 11.9%, respectively). The ratio of glutamate/cysteine/glycine was 1.4:1.4:1.0, which is similar to that for other
typical PCs. 相似文献
10.
11.
Atul Bhargava Sudhir Shukla Jatin Srivastava Nandita Singh Deepak Ohri 《Acta Physiologiae Plantarum》2008,30(1):111-120
Leaf samples were collected from 40 accessions of Chenopodium spp. and assessed for six heavy metals (Fe, Zn, Cu, Ni, Cr and Cd) accumulation to explore the use of Chenopodium for phytoextraction of heavy metals. The results suggest that Chenopodium spp. have the ability to accumulate large quantities of heavy metals in the leaf tissues even when they are present in low
concentrations in the soil. C. quinoa is a better accumulator of Ni, Cr and Cd than the rest of the species, while C. album accessions are good copper accumulators. Bioconcentration factor for chromium ranged from 0.36 (C. album “Chandanbathua”) to 6.57 (C. quinoa Ames 13719) with 13 accessions of C. quinoa scoring above the mean value. High heritability coupled with high genetic advance was recorded for Ni, Cr and Cd, which indicated
a major role of additive gene action in the inheritance of these characters. Zinc showed significant positive association
with iron (0.351**), nickel (0.659**), chromium (0.743**) and cadmium (0.288**). Nickel was significantly and negatively associated
with copper (−0.663**), while it was positively and significantly correlated with chromium (0.682**) and cadmium (0.461**).
Considering the accumulation efficiency of Chenopodium spp. with respect to heavy metals, this genus should be further explored for decontamination of metal polluted soils, with
plant breeding playing an important role in evolving new plant types with higher capacity of heavy metal accumulation. 相似文献
12.
13.
Aluminum (Al) toxicity is one of the major factors that limit plant growth in acid soils. Al-induced release of organic acids
into rhizosphere from the root apex has been identified as a major Al-tolerance mechanism in many plant species. In this study,
Al tolerance of Yuzu (Citrus Junos Sieb. ex Tanaka) was tested on the basis of root elongation and the results demonstrated that Yuzu was Al tolerant compared
with other plant species. Exposure to Al triggered the exudation of citrate from the Yuzu root. Thus, the mechanism of Al
tolerance in Yuzu involved an Al-inducible increase in citrate release. Aluminum also elicited an increase of citrate content
and increased the expression level of mitochondrial citrate synthase (CjCS) gene and enzyme activity in Yuzu. The CjCS gene was cloned from Yuzu and overexpressed in Nicotiana benthamiana using Agrobacterium tumefaciens-mediated methods. Increased expression level of the CjCS gene and enhanced enzyme activity were observed in transgenic plants compared with the wild-type plants. Root growth experiments
showed that transgenic plants have enhanced levels of Al tolerance. The transgenic Nicotiana plants showed increased levels of citrate in roots compared to wild-type plants. The exudation of citrate from roots of the
transgenic plants significantly increased when exposed to Al. The results with transgenic plants suggest that overexpression
of mitochondrial CS can be a useful tool to achieve Al tolerance. 相似文献
14.
Sayed Mehdi Hosseini Bahman Bahramnejad Hamed Douleti Baneh Aryo Emamifar Paul H. Goodwin 《World journal of microbiology & biotechnology》2017,33(4):67
Resveratrol is a polyphenolic compound produced in very low levels in grapes. To achieve high yield of resveratrol in wild grape, three Agrobacterium rhizogenes strains, Ar318, ArA4 and LBA9402, were used to induce hairy roots following infection of internodes, nodes or petioles of in vitro grown Vitis vinifera subsp. sylvesteris accessions W2 and W16, and cultivar Rasha. The effects of inoculation time, age of explants, bacterial concentration and co-cultivation times were examined on the efficiency of the production of hairy roots. Strains Ar318, ArA4 and LBA9402 all induced hairy roots in the tested genotypes, but the efficiency of ArA4 strain was higher than the other strains. The highest hairy root production was with using internodes as explants. The transformation of hairy roots lines was confirmed by PCR detection of rolB gene. Half Murashige and Skoog (MS) medium was better for biomass production compared with MS medium. HPLC analysis of resveratrol production in the hairy root cultures showed that all the genotypes produced higher amounts of resveratrol than control roots. The highest amount of resveratrol was produced from W16 internode cultures, which was 31-fold higher than that of control root. Furthermore, TLC analysis showed that treatments of hairy roots with sodium acetate and jasmonate elevated resveratrol levels both in hairy root tissue and excreted into the half MS medium. These results demonstrate that endogenous and exogenous factors can affect resveratrol production in hairy root culture of grape, and this strategy could be used to increase low resveratrol production in grapes. 相似文献
15.
Summary A heavy metal resistant bacterium, Bacillus circulans strain EB1 showed a high cadmium biosorption capacity coupled with a high tolerance to this metal when grown in its presence. Bacillus circulans EB1 cells grown in the presence of 28.1 mg cadmium/l were capable of removing cadmium with a specific biosorption capacity of 5.8 mg Cd/g dry wt biomass in the first 8 h. When the cells were pre-conditioned with low concentrations of cadmium in pre-grown medium, the uptake was increased to 6.7 mg Cd/g dry wt biomass. The maximum uptake of␣cadmium was during mid-logarithmic phase of growth. The resting cells (both wet and dry) of EB1 were also able to biosorb cadmium. Specific biosorption capacities of wet and dry biomass were 9.8 and 26.5 mg Cd/g dry wt biomass, respectively. Maximum cadmium removals by both wet and dry cells were at pH 7.0. The results showed that the cadmium removal capacity of resting cells was markedly higher than that of growing cells. Since both growing and resting cells had a high biosorption capacity for cadmium, EB1 cells could serve as an excellent biosorbent for removal of cadmium from natural environments. 相似文献
16.
Vânia L. Souza Alex-Alan F. de Almeida Stella G. C. Lima Júlio C. de M. Cascardo Delmira da C. Silva Pedro A. O. Mangabeira Fábio P. Gomes 《Biometals》2011,24(1):59-71
Cadmium (Cd) originating from atmospheric deposits, from industrial residues and from the application of phosphate fertilizers
may accumulate in high concentrations in soil, water and food, thus becoming highly toxic to plants, animals and human beings.
Once accumulated in an organism, Cd discharges and sets off a sequence of biochemical reactions and morphophysiological changes
which may cause cell death in several tissues and organs. In order to test the hypothesis that Cd interferes in the metabolism
of G. americana, a greenhouse experiment was conducted to measure eventual morphophysiological responses and cell death induced by Cd in
this species. The plants were exposed to Cd concentrations ranging from 0 to 16 mg l−1, in a nutritive solution. In TUNEL reaction, it was shown that Cd caused morphological changes in the cell nucleus of root
tip and leaf tissues, which are typical for apoptosis. Cadmium induced anatomical changes in roots and leaves, such as the
lignification of cell walls in root tissues and leaf main vein. In addition, the leaf mesophyll showed increase of the intercellular
spaces. On the other hand, Cd caused reductions in the net photosynthetic rate, stomatal conductance and leaf transpiration,
while the maximum potential quantum efficiency of PS2 (Fv/Fm) was unchanged. Cadmium accumulated in the root system in high concentrations, with low translocation for the shoot, and
promoted an increase of Ca and Zn levels in the roots and a decrease of K level in the leaves. High concentrations of Cd promoted
morphophysiological changes and caused cell death in roots and leaves tissues of G. americana. 相似文献
17.
Dandelion plants, the genus Taraxacum, are used in herbal medicine owing to their choleretic, diuretic and anti-carcinogenic activities and several medicinal compounds have been isolated from the roots of these plants. Metabolic manipulation of secondary metabolite biosynthesis is a potential strategy to improve the production of high-value secondary metabolites. The enzyme 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) is known to control a key regulatory step in the isoprenoid pathway. We report an efficient transformation protocol for stable introduction of HMGR into dandelion plants (Taraxacum platycarpum H. Dablstaed), which is essential for the biotechnological approach. The Agrobacterium tumefaciens strain EHA105 containing the binary vector, pCAMBIA1301, with GUS and HMGR genes, showed high transformation efficiency after 3–5 week hygromycin selection. Southern blotting, GUS staining and RT-PCR analyses demonstrated stable integration of one copy of the HMGR gene into the dandelion genome. Expression of the integrated genes was particularly eminent in root tissues of primary transformant plants. The establishment of an efficient transformation method may facilitate the improvement of medicinal plant in terms of the accumulation levels of secondary metabolites. 相似文献
18.
Phytochelatins (PCs) are heavy metal binding peptides that play an important role in sequestration and detoxification of heavy
metals in plants. In this study, our goal was to develop transgenic plants with increased tolerance for and accumulation of
heavy metals from soil by expressing an Arabidopsis
thaliana
AtPCS1 gene, encoding phytochelatin synthase (PCS), in Indian mustard (Brassica juncea L.). A 35S promoter fused to a FLAG–tagged AtPCS1 cDNA was expressed in Indian mustard, and transgenic lines, designated pc lines, were evaluated for tolerance to and accumulation
of Cd and Zn. Transgenic plants with moderate AtPCS1 expression levels showed significantly higher tolerance to Cd and Zn
stress, but accumulated significantly less Cd and Zn than wild type plants in both shoot and root tissues. However, transgenic
plants with highest expression of the transgene did not exhibit enhanced Cd and Zn tolerance. Shoots of Cd-treated pc plants
had significantly higher levels of phytochelatins and thiols than wild-type plants. Significantly lower concentrations of
gluthatione in Cd-treated shoot and root tissues of transgenic plants were observed. Moderate expression levels of phytochelatin
synthase improved the ability of Indian mustard to tolerate certain levels of heavy metals, but at the same time did not increase
the accumulation potential for Cd and Zn. 相似文献
19.
Telomerase activity was examined in two species of bat, Hipposideros armiger and Rousettus leschenaultia, which have similar body mass and lifespan but differ in use of hibernation. We found that telomerase activity was present
in all tissues sampled, but it was greater in metabolically active tissues such as liver, spleen, and kidney. Of special interest
is the raised activity found in the heterothermic bat H. armiger, and the hibernating bats having raised values for spleen, heart, and kidney. These findings show that maintenance of high
levels of telomerase is an essential part of the regulation of cellular activities during hibernation. 相似文献
20.
Karin Nuernberg Jaroslav Slamecka Jozef Mojto Jozef Gasparik Gerd Nuernberg 《European Journal of Wildlife Research》2011,57(4):795-803
The aim of this investigation was to characterise the fatty acid composition within intramuscular fat (IMF) of two muscles
(breast and thigh) from 28 pheasants, ten wild ducks and 27 black coots from Slovakia. A high variability for all single fatty
acids (FA) and the total fat concentration in muscles of wild birds was identified. Black coots deposited the highest fat
in breast muscle whereas wild ducks and pheasants accumulated more lipids in thigh muscle. In general, the content of polyunsaturated
fatty acids (PUFA) of the IMF in wild bird muscles was high, and the saturated FA concentration was lower compared with muscles
of domestic farm animals. The ratio between PUFA and saturated fatty acids (PSQ) ranked between 0.6 and 1.2, and the ratio
of n-6/n-3 fatty acid was favourably low in black coot and wild pheasants (3.2 and 2.9, respectively). Farmed pheasants had increased
IMF and more saturated and n-6 fatty acids deposited in thigh muscle but not in breast muscle. 相似文献