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Arabidopsis Thaliana Plants (arabidopsi + thaliana_plant)
Selected AbstractsHighly efficient targeting and accumulation of a Fab fragment within the secretory pathway and apoplast of Arabidopsis thalianaFEBS JOURNAL, Issue 15 2001Koen Peeters To further improve antibody production in plants, constructs were designed to minimize transgene silencing and to retain a Fab fragment within the secretory pathway of transgenic Arabidopsis thaliana plants. The levels of antibody accumulation suggest that placing the sequences that encode Fd and light chain under the control of nonidentical 3, regions reduces susceptibility to post-transcriptional gene silencing compared with when the individual polypeptide-encoding sequences are placed under the control of identical 3, regions. High levels of accumulation (up to 6% of total soluble protein) were found for both secreted and intracellularly targeted antibody fragments. Immunofluorescence microscopic analysis showed that Fab fragments devoid of any additional C-terminal sequence were efficiently secreted, whereas retention of Fab fragments within the endomembrane system of the secretory pathway was achieved by C-terminal fusion of the DIKDEL sequence to the antibody light chain. Furthermore, analysis by immunoprecipitation and ELISA showed that intracellular retention of antibody fragments did not affect antigen-binding activity, and more than 80% of the isolated antibody fragments were found to bind antigen. Taken together, our results provide improvements to the technology of recombinant antibody production in transgenic plants. [source] Lipopolysaccharide mobility in leaf tissue of Arabidopsis thalianaMOLECULAR PLANT PATHOLOGY, Issue 6 2010DANA ZEIDLER SUMMARY Bacterial lipopolysaccharides (LPS) are triggers of defence responses in plants, and induce local as well as systemic acquired resistance. Arabidopsis thaliana plants pretreated with LPS show an increased resistance to the virulent bacterial plant pathogen Pseudomonas syringae pv. tomato DC3000. To investigate the mobilization and transport of LPS in Arabidopsis leaves, fluorescently labelled LPS (Alexa Fluor® 488 conjugate) from Salmonella minnesota was used. Leaves were pressure infiltrated with fluorescein-labelled LPS and fluorescence microscopy was used to follow the movement and localization of LPS as a function of time. The observation of leaves 1 h after supplementation with fluorescein-labelled LPS revealed a fluorescent signal in the intercellular space. Capillary zone electrophoresis was used for the detection and analysis of the labelled LPS in directly treated leaves and systemic leaves. In addition, gel electrophoresis was used to confirm LPS mobilization. The results indicated that LPS mobilization/translocation occurs through the xylem from local, treated leaves to systemic, untreated leaves. Consequently, care should be taken when ascribing the observed biochemical responses and induced resistance from LPS perception as being uniquely local or systemic, as these responses might overlap because of the mobility of LPS in the plant vascular system. [source] Arabidopsis thaliana acyl-CoA-binding protein ACBP2 interacts with heavy-metal-binding farnesylated protein AtFP6NEW PHYTOLOGIST, Issue 1 2009Wei Gao Summary ,,Arabidopsis thaliana acyl-CoA-binding protein 2 (ACBP2) was observed to interact with farnesylated protein 6 (AtFP6), which has a metal-binding motif (M/LXCXXC). Their interaction and expression in response to heavy metals were investigated. ,,Yeast two-hybrid analysis and in vitro assays showed that an ACBP2 derivative lacking ankyrin repeats did not interact with AtFP6, indicating that the ankyrin repeats mediate protein,protein interaction. Autofluorescence-tagged ACBP2 and AtFP6 transiently co-expressed in tobacco (Nicotiana tabacum) were both targeted to the plasma membrane. ,,Reverse transcriptase polymerase chain reaction and northern blot analyses revealed that AtFP6 mRNA was induced by cadmium (Cd(II)) in A. thaliana roots. Assays using metal-chelate affinity chromatography demonstrated that in vitro translated ACBP2 and AtFP6 bound lead (Pb(II)), Cd(II) and copper (Cu(II)). Consistently, assays using fluorescence analysis confirmed that (His)6 -AtFP6 bound Pb(II), like (His)6 -ACBP2. ,,Arabidopsis thaliana plants overexpressing ACBP2 or AtFP6 were more tolerant to Cd(II) than wild-type plants. Plasma membrane-localized ACBP2 and AtFP6 probably mediate Pb(II), Cd(II) and Cu(II) transport in A. thaliana roots. Also, (His)6 -ACBP2 binds [14C]linoleoyl-CoA and [14C]linolenoyl-CoA, the precursors for phospholipid repair following lipid peroxidation under heavy metal stress at the plasma membrane. ACBP2 -overexpressing plants were more tolerant to hydrogen peroxide than wild-type plants, further supporting a role for ACBP2 in post-stress membrane repair. [source] A role for protein kinase CK2 in plant development: evidence obtained using a dominant-negative mutantTHE PLANT JOURNAL, Issue 1 2008Jordi Moreno-Romero Summary Protein kinase CK2 is an evolutionary conserved Ser/Thr phosphotransferase composed of two distinct subunits, , (catalytic) and , (regulatory), that combine to form a tetrameric complex. Plant genomes contain multiple genes for each subunit, the expression of which gives rise to different active holoenzymes. In order to study the effects of loss of function of CK2 on plant development, we have undertaken a dominant-negative mutant approach. We generated an inactive catalytic subunit by site-directed mutagenesis of an essential lysine residue. The mutated open reading frame was cloned downstream of an inducible promoter, and stably transformed Arabidopsis thaliana plants and tobacco BY2 cells were isolated. Continuous expression of the CK2 kinase-inactive subunit did not prevent seed germination, but seedlings exhibited a strong phenotype, affecting chloroplast development, cotyledon expansion, and root and shoot growth. Prolonged induction of the transgene was lethal. Moreover, dark-germinated seedlings exhibited an apparent de-etiolated phenotype that was not caused by disruption of the light-signalling pathways. Short-term induction of the CK2 kinase-inactive subunit allowed plant survival, but root growth and lateral root formation were significantly affected. The expression pattern of CYCB1;1::GFP in the root meristems of mutant plants demonstrated an important decrease of mitotic activity, and expression of the CK2 kinase-inactive subunit in stably transformed BY2 cells provoked perturbation of the G1/S and G2 phases of the cell cycle. Our results are consistent with a model in which CK2 plays a key role in cell division and cell expansion, with compelling effects on Arabidopsis development. [source] Cuticular defects lead to full immunity to a major plant pathogenTHE PLANT JOURNAL, Issue 6 2007Céline Chassot Summary In addition to its role as a barrier, the cuticle is also a source of signals perceived by invading fungi. Cuticular breakdown products have been shown previously to be potent inducers of cutinase or developmental processes in fungal pathogens. Here the question was addressed as to whether plants themselves can perceive modifications of the cuticle. This was studied using Arabidopsis thaliana plants with altered cuticular structure. The expression of a cell wall-targeted fungal cutinase in A. thaliana was found to provide total immunity to Botrytis cinerea. The response observed in such cutinase-expressing plants is independent of signal transduction pathways involving salicylic acid, ethylene or jasmonic acid. It is accompanied by the release of a fungitoxic activity and increased expression of members of the lipid transfer protein, peroxidase and protein inhibitor gene families that provide resistance when overexpressed in wild-type plants. The same experiments were made in the bodyguard (bdg) mutant of A. thaliana. This mutant exhibits cuticular defects and remained free of symptoms after inoculation with B. cinerea. The expression of resistance was accompanied by the release of a fungitoxic activity and increased expression of the same genes as observed in cutinase-expressing plants. Structural defects of the cuticle can thus be converted into an effective multi-factorial defence, and reveal a hitherto hidden aspect of the innate immune response of plants. [source] Maize Rabl7 overexpression in Arabidopsis plants promotes osmotic stress toleranceANNALS OF APPLIED BIOLOGY, Issue 3 2004M FIGUERAS Summary Rabl7 is a Late Embryogenesis Abundant (LEA) protein from maize, which accumulates largely during embryogenesis and also in vegetative tissues when subjected to stress conditions. We have analysed the effect of Rab 17 expression under a constitutive promoter in vegetative tissues of transgenic Arabidopsis thaliana plants. These transgenic plants have higher sugar and proline contents, and also higher water loss rate under water stress. In addition, these plants are more tolerant than non-transformed controls to high salinity and recover faster from mannitol treatment. Our results point to a protective effect of Rabl7 protein in vegetative tissues under osmotic stress conditions. [source] | ||||||||||