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1.
The precision of extrachromosomal homologous recombination and gene targeting in plant cells was investigated. Recombination was directed to introns of selectable marker genes where potential changes could persist without affecting the function and therefore the selectability of the genes. Approximately 9 kb of crossover regions was rescued and sequenced. Changes were detected at a frequency below one point mutation per 1000 bp, indicating that extrachromosomal recombination and gene targeting both appear to occur with high fidelity. 相似文献
2.
Chloroplasts are bounded by a pair of outer membranes, the envelope, that is the only permanent membrane structure of the
different types of plastids. Chloroplasts have had a long and complex evolutionary past and integration of the envelope membranes
in cellular functions is the result of this evolution. Plastid envelope membranes contain a wide diversity of lipids and terpenoid
compounds serving numerous biochemical functions and the flexibility of their biosynthetic pathways allow plants to adapt
to fluctuating environmental conditions (for instance phosphate deprivation). A large body of knowledge has been generated
by proteomic studies targeted to envelope membranes, thus revealing an unexpected complexity of this membrane system. For
instance, new transport systems for metabolites and ions have been identified in envelope membranes and new routes for the
import of chloroplast-specific proteins have been identified. The picture emerging from our present understanding of plastid
envelope membranes is that of a key player in plastid biogenesis and the co-ordinated gene expression of plastid-specific
protein (owing to chlorophyll precursors), of a major hub for integration of metabolic and ionic networks in cell metabolism,
of a flexible system that can divide, produce dynamic extensions and interact with other cell constituents. Envelope membranes
are indeed one of the most complex and dynamic system within a plant cell. In this review, we present an overview of envelope
constituents together with recent insights into the major functions fulfilled by envelope membranes and their dynamics within
plant cells.
Special Issue of Photosynthesis Research in honor of Andrew A. Benson. 相似文献
3.
Xiuyan Ren Fang Liu Zhilong Bao Chunling Zhang Xiaojing Wu Lei Chen Ruoxue Liu Hansong Dong 《Plant Molecular Biology Reporter》2008,26(3):225-240
HrpNEa is a harpin protein from Erwinia amylovora, a bacterial pathogen that causes fire blight in rosaceous plants. Treating plants with HrpNEa stimulates ethylene and abscisic acid (ABA) to induce plant growth and drought tolerance, respectively. Herein, we report
that both growth hormones cooperate to mediate the role of HrpNEa in promoting root growth of Arabidopsis thaliana seedlings. Root growth is promoted coordinately with elevation in levels of ABA and ethylene subsequent to soaking of germinating
seeds of wild-type (WT) Arabidopsis in a solution of HrpNEa. However, these responses are arrested by inhibiting WT roots from synthesizing ethylene as well as sensing of ABA and ethylene.
The effects of HrpNEa on roots are also nullified in ethylene-insensitive etr1-1 and ein5-1 mutants and in the ABA-insensitive mutant abi2-1 of Arabidopsis. These results provide evidence for presence of a relationship between root growth enhancement and signaling by ABA and ethylene
in response to HrpNEa. Nevertheless, when HrpNEa is applied to leaves, ethylene signaling is active in the absence of ABA signaling to promote plant growth. This suggests
the presence of a different signaling mechanism in leaves from that in roots.
X. Ren and F. Liu contributed equally to this study and are regarded as joint first authors 相似文献
4.
D. Menzel 《Protoplasma》1986,134(1):30-42
Summary The cytoskeleton in the siphonous, marine green algaAcetabularia is visualized by immunocytochemistry using antibodies against plant alfa tubulin and animal smooth muscle actin. In the vegetative phase of the life cycle, when the cell grows a cylindrical stalk and until the reproductive cap is completed, actin forms continuous, parallel bundles that extend through the entire length of the stalk and cap rays respectively. Microtubules (MTs) cannot be detected until the primary nucleus, located in the rhizoid of the giant cell, divides to form thousands of secondary nuclei. MTs can then be seen radiating from each secondary nucleus that is encountered in the stalk on its migration upwards into the cap rays. They are oriented mostly parallel to the long axis of the cell. At arrival in the cap rays up to the white spot stage, when nuclei assume equidistant positions in the cap ray cytoplasm, a radiating system of MTs forms around each nucleus and dramatically increases until impressive radial arrays have developed. This phase coincides with a disappearance of actin bundles in the cap rays, but they are retained in the stalk cytoplasm. Shortly after that additional MTs appear around the disk like partitions of cap ray cytoplasm. Concomitantly, bundles of actin reappear colinearly with the circumferrential MTs eventually forming complete rings around each disk of cap ray cytoplasm. During this process the compartments of the future cysts are gradually bulging outwards and simultaneously the rings of actin sink inwards until domes are formed with the nuclei fixed in the top centers of the domes. At this stage the peripheral areas of the radiating MT systems around the nuclei start to break down, whereas the circumferrential MT systems remain intact. Subsequently, the rings of both actin and MTs decrease in diameter, and finally contract to a spot opposite the nucleus, while the cysts continue to develop their oval shape. After the cysts have become separated, they round up and enter several rounds of nuclear divisions. MTs form short radial arrays around each nucleus with minor changes due to a reduction of MTs during division followed by a reappearance after completion of each division. Actin is rearranged in the cysts to a cortical network of randomly oriented, short bundles, that is maintained until gamete formation sets in.These findings accentuate the involvement of Cytoskeletal elements in the key steps of morphogenesis inAcetabularia to an extent that is unknown in higher plants. 相似文献
5.
Growth promoting effect of a transgenic <Emphasis Type="Italic">Bacillus mucilaginosus</Emphasis> on tobacco planting 总被引:1,自引:0,他引:1
Li X Wu Z Li W Yan R Li L Li J Li Y Li M 《Applied microbiology and biotechnology》2007,74(5):1120-1125
In this study, we have investigated the plant growth promoting effect of Bacillus mucilaginosus strain D4B1, a rhizosphere soil organism, and its transgenic strain NKTS-3 on tobacco planting. The transgenic strain contains a phytase
expression cassette that can express high active phytase extracellularly and hydrolyze phytate in the soil to liberate inorganic
phosphorus for the growth of tobacco plants. Greenhouse study and field experiments showed that both wild-type B. mucilaginosus and the transgenic strain could promote tobacco plant growth. Moreover, the transgenic strain promoted tobacco plant growth
(235% more than control in pot experiments and 125% more than control in field experiments) was higher than the wild-type
B. mucilaginosus (183% more than control in pot experiments and 108% more than control in field experiments). In addition, the inoculation
with transgenic rhizobacteria could significantly improve root acquisition of phosphorus and increase the phosphorus content
of the plant. 相似文献
6.
The stoloniferous herb Trifolium repens was used to study the expression of induced systemic resistance (ISR) to the generalist caterpillar Spodoptera exigua in interconnected ramets of clonal fragments. The ISR was assessed as caterpillar preference in dual choice tests between control and systemically induced plants. The ISR was detected in young ramets, after inducing older sibling ramets on the same stolon by a controlled herbivore attack. However, older ramets did not receive a defense induction signal from younger ramets unless the predominant phloem flow was reversed by means of basal shading. This provides evidence for the notion that in T. repens the clone-internal expression of ISR is coupled to phloem transport and follows source–sink gradients. The inducibility of the genotypes was not linked to their constitutive ability to produce cyanide, implying the absence of a trade-off between these two defense traits. To our knowledge, this is the first study that explores ISR to herbivory in the context of physiological integration in potentially extensive clonal plant networks. 相似文献
7.
Thelander M Nilsson A Olsson T Johansson M Girod PA Schaefer DG Zrÿd JP Ronne H 《Plant molecular biology》2007,64(5):559-573
The yeast Snf1, animal AMPK, and plant SnRK1 protein kinases constitute a family of related proteins that have been proposed
to serve as metabolic sensors of the eukaryotic cell. We have previously reported the characterization of two redundant SnRK1
encoding genes (PpSNF1a and PpSNF1b) in the moss Physcomitrella patens. Phenotypic analysis of the snf1a snf1b double knockout mutant suggested that SnRK1 is important for the plant’s ability to recognize and adapt to conditions of
limited energy supply, and also suggested a possible role of SnRK1 in the control of plant development. We have now used a
yeast two-hybrid system to screen for PpSnf1a interacting proteins. Two new moss genes were found, PpSKI1 and PpSKI2, which encode highly similar proteins with homologues in vascular plants. Fusions of the two encoded proteins to the green
fluorescent protein localize to the nucleus. Knockout mutants for either gene have an excess of gametophores under low light
conditions, and exhibit reduced gametophore stem lengths. Possible functions of the new proteins and their connection to the
SnRK1 kinase are discussed. 相似文献
8.
Summary Juvenile plants ofPlantago lanceolata andP. major ssp.major were grown in a flowing solution system at 7.5 mM or 9.5 M NO3. The parameters investigated were: RGR, shoot weight percentage, leaf length, length of main root axis, shoot concentrations of major ions and organic N, and the specific uptake rate for NO3. At 9.5 M NO3 growth ofP. major was not hampered, whereas shoot growth and leaf length ofP. lanceolata were reduced. The NO3 concentration ofP. lanceolata decreased more than that ofP. major. The different performances of the species at 9.5 M NO3 were associated with different specific uptake rates. In both treatments the root system ofP. major was shorter than that ofP. lanceolata. P. lanceolata accumulated more NO3 in the leaves. The performance of thePlantago species is discussed in relation to the availability of nutrients in their habitats.Grassland Species Research Group. Publication no. 37. 相似文献
9.
A rhizobacterial population of 2430 Pseudomonas isolates, originating from one maize hybrid and from its parents, was screened for auxins production. Four hundred and twelve isolates were found to be auxin producers (aia+), and 27 of them were also part of a previously described PhlD+ sub-population. Interestingly, most part of the aia(+)-PhlD+ isolates came from the hybrid. This finding indicates that heterosis allows an increased colonisation by multi-beneficial PGPR strains. Furthermore, results on the abundance and genetic diversity of aia+ isolates gave evidence that maize root colonisation by aia+ Pseudomonas is an inherited trait regulated by heterosis. In fact, two times more aia+ isolates were obtained from the rhizosphere of the hybrid than from the rhizospheres of the parents, and an amplified rDNA restriction analysis showed that the hybrid increases the genetic diversity of aia+ populations when compared to its parents. 相似文献
10.
Ascomycota are among the fungi that cause serious willow diseases in all natural habitats worldwide. This study was conducted
to determine if basket willow used in green wall structures (GWS) built of willow stems were infected by potentially important
fungal diseases or their antagonists in urban areas of eastern Canada. In total, 13 different phenotypic genera belonging
to eight families of ascomycetous fungi were isolated and identified according to their sexual and/or asexual forms. Venturia pathogenic species complex were represented by three different anamorphs: Fusicladium, Fusicladium-Cladosporium, and Pollaccia as anamorph. They were responsible for the highest incidence value on leaves (IF > 15%). Cryptodiaporthe, Drepanopeziza, and Glomerella dominated on bark (IF > 5%). A significantly higher incidence value of fungal communities was found on first year than on
second year GWS. The correspondence analysis using χ2 distance showed that communities of potentially pathogenic species are closely related to diseased plants, while healthy
plants often contain biocontrol species such as Cladobotryum mycoparasite on healthy bark and Alternaria sp. antagonist on healthy leaves. The phylogenetic positions of the different fungal taxa and their relationship have been
revealed by use of PCR amplified internal transcriber spacer (ITS) region of rDNA. 相似文献