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1.
Visualization of a cytoskeleton-like FtsZ network in chloroplasts   总被引:20,自引:0,他引:20  
It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton. Recently, this belief was questioned by the finding that the bacterial cell division protein FtsZ resembles tubulin in sequence and structure and, thus, may be the progenitor of this major eukaryotic cytoskeletal element. Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure. Both their encoded proteins are imported into plastids and there, like in bacteria, they act on the division process in a dose-dependent manner. Whereas in bacteria FtsZ only transiently polymerizes to a ring-like structure, in chloroplasts we identified persistent, highly organized filamentous scaffolds that are most likely involved in the maintenance of plastid integrity and in plastid division. As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term "plastoskeleton" for this newly described subcellular structure.  相似文献
2.
A tool for understanding homologous recombination in plants   总被引:6,自引:0,他引:6  
Hohe A  Reski R 《Plant cell reports》2003,21(12):1135-1142
Attempts for establishing an efficient gene targeting (GT) system in seed plants have hitherto not been successful. In contrast, GT based on homologous recombination is highly efficient in Physcomitrella, making this moss a novel tool in reverse genetics. However, why homologous and illegitimate recombination are differently regulated between Physcomitrella and seed plants is still enigmatic. Here we update the state of the art of GT in Physcomitrella and discuss approaches to unravel this enigma. Identification of molecular factors significantly enhancing GT and their subsequent transfer to crop plants will have a great impact on plant biotechnology by enabling precise genetic engineering. Physcomitrella appears to be the most useful model system in this context.  相似文献
3.
The plant hormone auxin plays a major role in a variety of growth and developmental responses, even in the more ancient plants-for example, cell differentiation in mosses. Nevertheless, almost nothing is known about the distribution of auxin during moss development. To address this question, we characterised auxin distribution in the moss Physcomitrella patens using auxin-inducible reporter gene systems. Stable transgenic Physcomitrella plants were produced expressing the beta-glucuronidase (GUS) gene driven by the auxin-inducible promoters GH3 and DR5, respectively. Both fusions showed remarkable differences with respect to auxin-induced promoter strength and expression kinetics. A detailed characterisation of the GUS expression pattern in different developmental stages revealed that the highest auxin concentrations were in dividing and ontogenetic young cells.  相似文献
4.
The mechanisms plants use to adapt to abiotic stress have been widely studied in a number of seed plants. Major research has been focused on the isolation of stress-responsive genes as a means to understand the molecular events underlying the adaptation process. To study stress-related gene regulation in the moss Physcomitrella patens we have isolated two cDNAs showing homology to highly conserved small hydrophobic proteins from different seed plants. The corresponding genes are up-regulated by dehydration, salt, sorbitol, cold and the hormone abscisic acid, indicating overlapping pathways are involved in the control of these genes. Based on the molecular characterization of the moss homologs we propose that signaling pathways in response to abiotic stress may have been altered during the evolution of land plants.Abbreviation ABA Abscisic acid - EST Expressed sequence tag  相似文献
5.
Do we need another model plant?   总被引:1,自引:0,他引:1  
6.
Glyco-engineering of moss lacking plant-specific sugar residues   总被引:1,自引:0,他引:1  
The commercial production of complex pharmaceutical proteins from human origin in plants is currently limited through differences in protein N-glycosylation pattern between plants and humans. On the one hand, plant-specific alpha(1,3)-fucose and beta(1,2)-xylose residues were shown to bear strong immunogenic potential. On the other hand, terminal beta(1,4)-galactose, a sugar common on N-glycans of pharmaceutically relevant proteins, e.g., antibodies, is missing in plant N-glycan structures. For safe and flexible production of pharmaceutical proteins, the humanisation of plant protein N-glycosylation is essential. Here, we present an approach that combines avoidance of plant-specific and introduction of human glycan structures. Transgenic strains of the moss Physcomitrella patens were created in which the alpha(1,3)-fucosyltransferase and beta(1,2)-xylosyltransferase genes were knocked out by targeted insertion of the human beta(1,4)-galactosyltransferase coding sequence in both of the plant genes (knockin). The transgenics lacked alpha(1,3)-fucose and beta(1,2)-xylose residues, whereas beta(1,4)-galactose residues appeared on protein N-glycans. Despite these significant biochemical changes, the plants did not differ from wild type with regard to overall morphology under standard cultivation conditions. Furthermore, the glyco-engineered plants secreted a transiently expressed recombinant human protein, the vascular endothelial growth factor, in the same concentration as unmodified moss, indicating that the performed changes in glycosylation did not impair the secretory pathway of the moss. The combined knockout/knockin approach presented here, leads to a new generation of engineered moss and towards the safe and flexible production of correctly processed pharmaceutical proteins with humanised N-glycosylation profiles.  相似文献
7.
The moss Physcomitrella patens has become a powerful model system in modern plant biology. Highly standardized cell culture techniques, as well as the necessary tools for computational biology, functional genomics and proteomics have been established. Large EST collections are available and the complete moss genome will be released soon. A simple body plan and the small number of different cell types in Physcomitrella facilitate the study of developmental processes. In the filamentous juvenile moss tissue, developmental decisions rely on the differentiation of single cells. Developmental steps are controlled by distinct phytohormones and integration of environmental signals. Especially the phytohormones auxin, cytokinin, and abscisic acid have distinct effects on early moss development. In this article, we review current knowledge about phytohormone influences on early moss development in an attempt to fully unravel the complex regulatory signal transduction networks underlying the developmental decisions of single plant cells in a holistic systems biology approach.  相似文献
8.
9.
Gene targeting in the moss Physcomitrella patens has created a new platform for plant functional genomics. We produced a mutant collection of 73 329 Physcomitrella plants and evaluated the phenotype of each transformant in comparison to wild type Physcomitrella. Production parameters and morphological changes in 16 categories, such as plant structure, colour, coverage with gametophores, cell shape, etc., were listed and all data were compiled in a database (mossDB). Our mutant collection consists of at least 1804 auxotrophic mutants which showed growth defects on minimal Knop medium but were rescued on supplemented medium. 8129 haploid and 11 068 polyploid transformants had morphological alterations. 9 % of the haploid transformants had deviations in the leaf shape, 7 % developed less gametophores or had a different leaf cell shape. Other morphological deviations in plant structure, colour, and uniformity of leaves on a moss colony were less frequently observed. Preculture conditions of the plant material and the cDNA library (representing genes from either protonema, gametophore or sporophyte tissue) used to transform Physcomitrella had an effect on the number of transformants per transformation. We found correlations between ploidy level and plant morphology and growth rate on Knop medium. In haploid transformants correlations between the percentage of plants with specific phenotypes and the cDNA library used for transformation were detected. The number of different cDNAs present during transformation had no effect on the number of transformants per transformation, but it had an effect on the overall percentage of plants with phenotypic deviations. We conclude that by linking incoming molecular, proteome, and metabolome data of the transformants in the future, the database mossDB will be a valuable biological resource for systems biology.  相似文献
10.
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