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Model Plant Arabidopsis Thaliana (model + plant_arabidopsi_thaliana)
Selected AbstractsThe Arabidopsis class VIII myosin ATM2 is involved in endocytosisCYTOSKELETON, Issue 6 2008Amirali Sattarzadeh Abstract Members of the class XI of the myosin superfamily comprising higher plant, actin-based molecular motors have been shown to be involved in peroxisome and Golgi vesicle trafficking comparable to yeast and animal class V myosins. The tasks of the second class of myosins of higher plants, class VIII, are unclear. In this study the class VIII myosin ATM2 from the model plant Arabidopsis thaliana was selected for the examination of cargo specificity in vivo. Fluorescent protein-fusion plasmid constructs with fragments of the ATM2 cDNA were generated and used for Agrobacterium tumefaciens -based transient transformation of Nicotiana benthamiana leaves. The resulting subcellular localization patterns were recorded by live imaging with confocal laser scanning microscopy (CLSM) in epidermal leaf cells. Expression of a nearly full-length construct displayed labeling of filaments and vesicles, a head + neck fragment led to decoration of filaments only. However, expression of fluorescent protein-tagged C-terminal tail domain constructs labeled vesicular structures of different appearance. Most importantly, coexpression of different RFP/YFP-ATM2 tail fusion proteins showed colocalization and, hence, binding to the same type of vesicular target. Further coexpression experiments of RFP/YFP-ATM2 tail fusion proteins with the endosomal marker FYVE and the endosomal tracer FM4-64 demonstrated colocalization with endosomes. Colocalization was also detected by expression of the CFP-tagged membrane receptor BRI1 as marker, which is constantly recycled via endosomes. Occasionally the ATM2 tail targeted to sites at the plasma membrane closely resembling the pattern obtained upon expression of the YFP-ATM1 C-terminal tail. ATM1 is known for its localization at the plasma membrane at sites of plasmodesmata. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Developing transgenic arabidopsis plants to be metal-specific bioindicatorsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Beth A. Krizek Abstract Deoxyribonucleic acid (DNA) microarrays provide a means to assess genome-wide expression patterns after exposure of an organism to different xenobiotics. Potential uses for this technology include identification of unknown toxicants, assessment of toxicity of new compounds, and characterization of the cellular mechanisms of toxicant action. Here we describe another use of DNA microarrays in toxicant-specific gene discovery. Combining results from two DNA microarray experiments, we have identified genes from the model plant Arabidopsis thaliana that are induced in response to one but not other heavy metals. The promoters of these genes should be useful in developing metal-specific transgenic biomonitors. To test this idea, we have fused the promoter of one of the newly identified Ni-inducible genes (AHB1) to the ,-glucuronidase (GUS) reporter gene. Arabidopsis plants containing the AHB1::GUS transgene show reporter gene activity when they are grown on media containing Ni but not when grown on media containing Cd, Cu, Zn, or without added metals. Thus, this approach has resulted in the creation of a transgenic strain of Arabidopsis that can report on the presence and concentration of Ni in plant growth media. Such transgenic models can serve as cheap and efficient biomonitors of bioavailable heavy metal contamination in soils and sediments. [source] Arabidopsis pathology breathes new life into the necrotrophs-vs.-biotrophs classification of fungal pathogensMOLECULAR PLANT PATHOLOGY, Issue 4 2004RICHARD P. OLIVER SUMMARY Fungal plant pathologists have for many decades attempted to classify pathogens into groups called necrotrophs, biotrophs and, more recently, hemibiotrophs. Although these terms are well known and frequently used, disagreements about which pathogens fall into which classes, as well as the precise definition of these terms, has conspired to limit their usefulness. Dogmas concerning the properties of the classes have been progressively eroded. However, the genetic analysis of disease resistance, particularly in the model plant Arabidopsis thaliana, has provided a biologically meaningful division based on whether defence against fungal pathogens is controlled via the salicylate or jasmonate/ethylene pathways. This mode-of-defence division distinguishes necrotrophs and biotrophs but it limits the biotroph class to pathogens that possess haustoria. The small number and limited range of pathogens that infect Arabidopsis means that several interesting questions are still unanswered. Do hemibiotrophs represents a distinct class or a subclass of the necrotrophs? Does the division apply to other plant families and particularly to cereals? and does this classification help us understand the intricacies of either fungal pathogenicity or plant defence? [source] Cold stress and acclimation , what is important for metabolic adjustment?PLANT BIOLOGY, Issue 3 2010A. Janská Abstract As sessile organisms, plants are unable to escape from the many abiotic and biotic factors that cause a departure from optimal conditions of growth and development. Low temperature represents one of the most harmful abiotic stresses affecting temperate plants. These species have adapted to seasonal variations in temperature by adjusting their metabolism during autumn, increasing their content of a range of cryo-protective compounds to maximise their cold tolerance. Some of these molecules are synthesised de novo. The down-regulation of some gene products represents an additional important regulatory mechanism. Ways in which plants cope with cold stress are described, and the current state of the art with respect to both the model plant Arabidopsis thaliana and crop plants in the area of gene expression and metabolic pathways during low-temperature stress are discussed. [source] Oxygen control of ethylene biosynthesis during seed development in Arabidopsis thaliana (L.) HeynhPLANT CELL & ENVIRONMENT, Issue 6 2002K. M. Ramonell Abstract An unforeseen side-effect on plant growth in reduced oxygen is the loss of seed production at concentrations around 25% atmospheric (50 mmol mol,1 O2). In this study, the model plant Arabidopsis thaliana (L.) Heynh. cv. ,Columbia' was used to investigate the effect of low oxygen on ethylene biosynthesis during seed development. Plants were grown in a range of oxygen concentrations (210 [equal to ambient], 160, 100, 50 and 25 mmol mol,1) with 0·35 mmol mol,1 CO2 in N2. Ethylene in full-sized siliques was sampled using gas chromatography, and viable seed production was determined at maturity. Molecular analysis of ethylene biosynthesis was accomplished using cDNAs encoding 1-aminocyclopropane -1-carboxylic acid (ACC) synthase and ACC oxidase in ribonuclease protection assays and in situ hybridizations. No ethylene was detected in siliques from plants grown at 50 and 25 mmol mol,1 O2. At the same time, silique ACC oxidase mRNA increased three-fold comparing plants grown under the lowest oxygen with ambient controls, whereas ACC synthase mRNA was unaffected. As O2 decreased, tissue-specific patterning of ACC oxidase and ACC synthase gene expression shifted from the embryo to the silique wall. These data demonstrate how low O2 modulates the activity and expression of the ethylene biosynthetic pathway during seed development in Arabidopsis. [source] Proteomics reveal tissue-specific features of the cress (Lepidium sativum L.) endosperm cap proteome and its hormone-induced changes during seed germinationPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2010Kerstin Müller Abstract Mature angiosperm seeds consist of an embryo surrounded by the endosperm and the testa. The endosperm cap that covers the radicle plays a regulatory role during germination and is a major target of abscisic acidinduced inhibition of germination. Cress (Lepidium sativum) is a close relative of the model plant Arabidopsis thaliana (Arabidopsis). Cress seeds offer the unique possibility of performing tissue-specific proteomics due to their larger size while benefiting the genomic tools available for Arabidopsis. This work provides the first description of endosperm cap proteomics during seed germination. An analysis of the proteome of the cress endosperm cap at key stages during germination and after radicle protrusion in the presence and absence of abscisic acid led to the identification of 144 proteins, which were clustered by the changes in their abundances and categorized by function. Proteins with a function in energy production, protein stability and stress response were overrepresented among the identified endosperm cap proteins. This strongly suggests that the cress endosperm cap is not a storage tissue as the cereal endosperm but a metabolically very active tissue regulating the rate of radicle protrusion. [source] Heteromeric K+ channels in plantsTHE PLANT JOURNAL, Issue 6 2008Anne Lebaudy Summary Voltage-gated potassium channels of plants are multimeric proteins built of four ,-subunits. In the model plant Arabidopsis thaliana, nine genes coding for K+ channel ,-subunits have been identified. When co-expressed in heterologous expression systems, most of them display the ability to form heteromeric K+ channels. Till now it was not clear whether plants use this potential of heteromerization to increase the functional diversity of potassium channels. Here, we designed an experimental approach employing different transgenic plant lines that allowed us to prove the existence of heteromeric K+ channels in plants. The chosen strategy might also be useful for investigating the activity and function of other multimeric channel proteins like, for instance, cyclic-nucleotide gated channels, tandem-pore K+ channels and glutamate receptor channels. [source] Expression, purification and preliminary X-ray diffraction studies of VERNALIZATION1208,341 from Arabidopsis thalianaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2009Gordon King VERNALIZATION1 (VRN1) is required in the model plant Arabidopsis thaliana for the epigenetic suppression of the floral repressor FLC by prolonged cold treatment. Stable suppression of FLC accelerates flowering, a physiological process known as vernalization. VRN1 is a 341-residue DNA-binding protein that contains two plant-specific B3 domains (B3a and B3b), a putative nuclear localization sequence (NLS) and two putative PEST domains. VRN1208,341 includes the second B3 domain and a region upstream that is highly conserved in the VRN1 orthologues of other dicotyledonous plants. VRN1208,341 was crystallized by the hanging-drop method in 0.05,M sodium acetate pH 6.0 containing 1.0,M NaCl and 18%(w/v) PEG 3350. Preliminary X-ray diffraction data analysis revealed that the VRN1208,341 crystal diffracted to 2.1,Å and belonged to space group C2, with unit-cell parameters a = 105.2, b = 47.9, c = 61.2,Å, , = 90.0, , = 115.4, , = 90.0°. Assuming that two molecules occupy the asymmetric unit, a Matthews coefficient of 2.05,Å3,Da,1 and a solvent content of 40.1% were calculated. [source] Identification of novel hrp -regulated genes through functional genomic analysis of the Pseudomonas syringae pv. tomato DC3000 genomeMOLECULAR MICROBIOLOGY, Issue 5 2002Julie Zwiesler-Vollick Summary Pseudomonas syringae pv. tomato ( Pst ) strain DC3000 infects the model plants Arabidopsis thaliana and tomato, causing disease symptoms characterized by necrotic lesions surrounded by chlorosis. One mechanism used by Pst DC3000 to infect host plants is the type III protein secretion system, which is thought to deliver multiple effector proteins to the plant cell. The exact number of type III effectors in Pst DC3000 or any other plant pathogenic bacterium is not known. All known type III effector genes of P. syringae are regulated by HrpS, an NtrC family protein, and the HrpL alternative sigma factor, which presumably binds to a conserved cis element (called the ,hrp box') in the promoters of type III secretion-associated genes. In this study, we designed a search motif based on the promoter sequences conserved in 12 published hrp operons and putative effector genes in Pst DC3000. Seventy-three predicted genes were retrieved from the January 2001 release of the Pst DC3000 genome sequence, which had 95% genome coverage. The expression of the 73 genes was analysed by microarray and Northern blotting, revealing 24 genes/operons (including eight novel genes), the expression of which was consistently higher in hrp -inducing minimal medium than in nutrient-rich Luria,Bertani broth. Expression of all eight genes was dependent on the hrpS gene. Most were also dependent on the hrpL gene, but at least one was dependent on the hrpS gene, but not on the hrpL gene. An AvrRpt2-based type III translocation assay provides evidence that some of the hrpS -regulated novel genes encode putative effector proteins. [source] | |||||||||||||