bluuebunny/crossref_metadata_2025_split huggingface dataset:
A highly specific pathogen‐responsive promoter element from the immediate‐early activated CMPG1 gene in Petroselinum crispum
Authors: Kirsch Christoph , Logemann Elke , Lippok Bernadette , Schmelzer Elmon , Hahlbrock Klaus 
Published: March 2003

SummaryWithin the complex signalling network from pathogen‐derived elicitor perception to defense‐related gene activation, some immediate‐early responding genes may have pivotal roles in downstream transcriptional regulation. We have identified the parsley (Petroselinum crispum) ELI17 gene as a particularly fast‐responding gene possessing a new type of W box‐containing, elicitor‐responsive promoter element, E17. Highly selective E17‐mediated reporter gene expression at pathogen infection sites in transgenic Arabidopsis thaliana plants demonstrated the potential of this promoter element for designing new strategies in resistance breeding as well as for further analysis of the early components of defense‐related gene activation mechanisms. The protein encoded by the ELI17 gene exhibits various structural characteristics of established transcription factors and is designated as a CMPG protein according to the first four strictly conserved amino acids defining a newly emerging class of plant‐specific proteins.
Transcriptional activation by the sexual pheromone and wounding: a new gene family from Volvox encoding modular proteins with (hydroxy)proline‐rich and metalloproteinase homology domains
Authors: Hallmann Armin , Amon Peter , Godl Klaus , Heitzer Markus , Sumper Manfred 
Published: March 2003

SummaryThe green alga Volvox represents the simplest kind of multicellular organism: it is composed of only two cell types, somatic and reproductive, making it suitable as a model system. The sexual development of males and females of Volvox carteri is triggered by a sex‐inducing pheromone at a concentration of < 10−16 m. Early biochemical responses to the pheromone involve structural modifications within the extracellular matrix (ECM). By differential screenings of cDNA libraries made from mRNAs of pheromone‐treated Volvox, four novel genes were identified that encode four closely related Volvox metalloproteinases that we use to define a new protein family, the VMPs. The existence of several features common to matrix glycoproteins, such as signal peptides, a (hydroxy)proline content of 12–25%, and Ser(Pro)2−4 repeats, suggest an extracellular localization of the VMPs within the ECM. Synthesis of VMP cDNAs is triggered not only by the sex‐inducing pheromone, but also by wounding, and is restricted to the somatic cell type. Sequence comparisons suggest that the VMPs are members of the MB clan of zinc‐dependent matrix metalloproteinases, although the putative zinc binding site of all VMPs is QEXXHXXGXXH rather than HEXXHXXGXXH. The presence of glutamine instead of histidine in the zinc binding motif suggests a novel family, or even clan, of peptidases. Like the matrixin family of human collagenases, Volvox VMPs exhibit a modular structure: they possess a metalloproteinase homology domain and a (hydroxy)proline‐rich domain, and one of them, VMP4, also has two additional domains. Metalloproteinases seem to be crucial for biochemical modifications of the ECM during development or after wounding in the lower eukaryote Volvox with only two cell types, just as in higher organisms.
The protein kinases AtMAP3Kε1 and BnMAP3Kε1 are functional homologues of S. pombe cdc7p and may be involved in cell division
Authors: Jouannic Stefan , Champion Anthony , Segui‐Simarro José‐Maria , Salimova Ekaterina , Picaud Alain , Tregear James , Testillano Pilar , Risueño Maria‐Carmen , Simanis Viesturs , Kreis Martin , Henry Yves 
Published: March 2003

SummaryWe identified an Arabidopsis thaliana gene, AtMAP3Kε1, and a Brassica napus cDNA, BnMAP3Kε1, encoding functional protein serine/threonine kinases closely related to cdc7p and Cdc15p from Schizosaccharomyces pombe and Saccharomyces cerevisiae, respectively. This is the first report of cdc7‐related genes in non‐fungal eukaryotes; no such genes have as yet been identified in Metazoans. The B. napus protein is able to partially complement a cdc7 loss of function mutation in S. pombe. RT–PCR and in situ hybridisation revealed that the A. thaliana and B. napus genes are expressed in both the sporophytic and the gametophytic tissues of the respective plant species and revealed further that expression is highest in dividing cells. Moreover, AtMAP3Kε1 gene expression is cell cycle‐regulated, with higher expression in G2‐M phases. Our results strongly suggest that the plant cdc7p‐related protein kinases are involved in a signal transduction pathway similar to the SIN pathway, which positively regulates cytokinesis in S. pombe.
Inducible high‐level mRNA amplification system by viral replicase in transgenic plants
Authors: Mori Masashi , Fujihara Naoko , Mise Kazuyuki , Furusawa Iwao 
Published: March 2003

SummaryWe have constructed a new system for inducible high‐level expression of mRNA for foreign genes in transgenic plants by introducing a glucocorticoid‐inducible transcription system into the previously developed ‘mRNA amplification system’ where target mRNA can be amplified as a subgenomic RNA by the replicase of a plant tripartite RNA virus, Brome mosaic virus (BMV). In the new amplification system, the amplification of mRNA is tightly regulated by the expression of a subunit of the BMV replicase. Transgenic Nicotiana benthamiana plants (designated GVG1 × 2FR) were produced that contained cDNA of BMV RNA1 coding a subunit of replicase under the control of a tightly regulated, glucocorticoid‐inducible promoter. In addition GVG1 × 2FR plants contain cDNAs of BMV RNA2 coding another subunit of the replicase, and a replicable engineered BMV RNA3 derivative (FCP2IFN) carrying the human gamma interferon (IFN) gene under the control of the Cauliflower mosaic virus 35S promoter. When transgenic plants were treated with dexamethasone (DEX), a strong synthetic glucocorticoid, induction of replication and amplification of the 35S‐driven FCP2IFN and synthesis of subgenomic mRNA for IFN were observed. Accumulation levels of amplified FCP2IFN were over 300 times higher than those of the 35S‐driven FCP2IFN in the GVG1 × 2FR plant without the treatment and those of the mRNA for IFN were 30–230 times higher than in the previous, non‐inducible mRNA amplification system. Without DEX treatment, no subgenomic mRNA for IFN was detected in the GVG1 × 2FR plant. The advantages and potential uses of this system are also discussed.
Evidence for a role in growth and salt resistance of a plasma membrane H+‐ATPase in the root endodermis
Authors: Vitart Veronique , Baxter Ivan , Doerner Peter , Harper Jeffrey F. 
Published: March 2003

SummaryThe plasma membrane of plant cells is energized by an electrochemical gradient produced by P‐type H+‐ATPases (proton pumps). These pumps are encoded by at least 12 genes in Arabidopsis. Here we provide evidence that isoform AHA4 contributes to solute transport through the root endodermis. AHA4 is expressed most strongly in the root endodermis and flowers, as suggested by promoter‐GUS reporter assays. A disruption of this pump (aha4–1) was identified as a T‐DNA insertion in the middle of the gene (after VFP574). Truncated aha4–1 transcripts accumulate to approximately 50% of the level observed for AHA4 mRNA in wild‐type plants. Plants homozygous for aha4–1 (–/–) show a subtle reduction in root and shoot growth compared with wild‐type plants when grown under normal conditions. However, a mutant phenotype is very clear in plants grown under salt stress (e.g., 75 or 110 mm NaCl). In leaves of mutant plants subjected to Na stress, the ratio of Na to K increased 4–5‐fold. Interestingly, the aha4–1 mutation appears to be semidominant and was only partially complemented by the introduction of additional wild‐type copies of AHA4. These results are consistent with the hypothesis that aha4–1 may produce a dominant negative protein or RNA that partially disrupts the activity of other pumps or functions in the root endodermal tissue, thereby compromising the function of this cell layer in controlling ion homeostasis and nutrient transport.
Mapping genes on an integrated sorghum genetic and physical map using cDNA selection technology
Authors: Childs Kevin L. , Klein Robert R. , Klein Patricia E. , Morishige Daryl T. , Mullet John E. 
Published: March 2003

SummarySorghum is an important target of plant genomics. This cereal has unusual tolerance to adverse environments, a small genome (750 Mbp) relative to most other grasses, a diverse germplasm, and utility for comparative genomics with rice, maize and other grasses. In this study, a modified cDNA selection protocol was developed to aid the discovery and mapping of genes across an integrated genetic and physical map of the sorghum genome. BAC DNA from the sorghum genome map was isolated and covalently bound in arrayed tubes for efficient liquid handling. Amplifiable cDNA sequence tags were isolated by hybridization to individual sorghum BACs, cloned and sequenced. Analysis of a fully sequenced sorghum BAC indicated that about 80% of known or predicted genes were detected in the sequence tags, including multiple tags from different regions of individual genes. Data from cDNA selection using the fully sequenced BAC indicate that the occurrence of mislocated cDNA tags is very low. Analysis of 35 BACs (5.25 Mb) from sorghum linkage group B revealed (and therefore mapped) two sorghum genes and 58 sorghum ESTs. Additionally, 31 cDNA tags that had significant homologies to genes from other species were also isolated. The modified cDNA selection procedure described here will be useful for genome‐wide gene discovery and EST mapping in sorghum, and for comparative genomics of sorghum, rice, maize and other grasses.
The ubiquitin‐specific protease UBP14 is essential for early embryo development in Arabidopsis thaliana
Authors: Doelling Jed H. , Yan Ning , Kurepa Jasmina , Walker Joseph , Vierstra Richard D. 
Published: March 2003

SummaryThe ubiquitin/26S proteasome pathway is a major route for selectively degrading cytoplasmic and nuclear proteins in eukaryotes. In this pathway, chains of ubiquitins become attached to short‐lived proteins, signalling recognition and breakdown of the modified protein by the 26S proteasome. During or following target degradation, the attached multi‐ubiquitin chains are released and subsequently disassembled by ubiquitin‐specific proteases (UBPs) to regenerate free ubiquitin monomers for re‐use. Here, we describe Arabidopsis thaliana UBP14 that may participate in this recycling process. Its amino acid sequence is most similar to yeast UBP14 and its orthologues, human IsoT1‐3 and Dictyostelium UbpA, and it can functionally replace yeast UBP14 in a ubp14Δ mutant. Like its orthologues, AtUBP14 can disassemble multi‐ubiquitin chains linked internally via ε‐amino isopeptide bonds using Lys48 and can process some, but not all, translational fusions of ubiquitin linked via α‐amino peptide bonds. However, unlike its yeast and Dictyostelium orthologues, AtUBP14 is essential in Arabidopsis. T‐DNA insertion mutations in the single gene that encodes AtUBP14 cause an embryonic lethal phenotype, with the homozygous embryos arresting at the globular stage. The arrested seeds have substantially increased levels of multi‐ubiquitin chains, indicative of a defect in ubiquitin recycling. Taken together, the data demonstrate an essential role for the ubiquitin/26S proteasome pathway in general and for AtUBP14 in particular during early plant development.
N‐terminal domains of plant poly(ADP‐ribose) polymerases define their association with mitotic chromosomes
Authors: Babiychuk Elena , Van Montagu Marc , Kushnir Sergei 
Published: March 2003

SummaryPoly(ADP‐ribos)ylation is a reversible protein modification that in higher plants is catalyzed by two structurally different poly(ADP‐ribose) polymerases, App and Zap. In vivo imaging of green‐fluorescent protein (GPF) fusions showed that both Zap and App were associated with chromatin through the cell cycle progression. The in vivo behaviour of the App‐GFP protein fusions can be attributed to the activity of two NASA motifs that mediate protein–protein interactions and nucleic acid binding. Expression of Zap deletion variants revealed that both Zn fingers and helix‐turn‐helix domains contributed to the association with chromosomes, whereas the localization in the nucleoplasm was mostly determined by the Zn fingers. The results highlight novel properties of protein sequences found in plant poly(ADP‐ribose) polymerases and suggest important functions for this class of nuclear enzymes in chromosome dynamics.
Linear DNA intermediates of the Tto1 retrotransposon in Gag particles accumulated in stressed tobacco and Arabidopsis thaliana
Authors: Takeda Shin , Sugimoto Kazuhiko , Kakutani Tetsuji , Hirochika Hirohiko 
Published: March 2003

SummaryThe active transcription of some plant retrotransposons under diverse stress conditions suggests active transposition. However, transposition has been demonstrated only during tissue/cell culture. To examine whether transposition is activated under conditions other than tissue/cell culture, DNA intermediates for retrotransposition of the tobacco retrotransposon Tto1 were analysed. Using transgenic Arabidopsis callus expressing high levels of Tto1 RNA in a ddm1 hypomethylation mutant background, the existence of extrachromosomal Tto1 linear DNA molecules in a Gag‐particle fraction was demonstrated. By combination with ligation‐mediated PCR amplification, we detected Tto1 linear DNA molecules in particle fractions from callus and methyl jasmonate‐treated leaves of tobacco, but not from non‐stressed leaves. Tto1 DNA intermediates could not be detected in the tobacco corolla where Tto1 is expressed. These results indicate that the transcriptional activation of Tto1 by defence‐related stresses leads to the synthesis of DNA intermediates, whereas post‐transcriptional suppression of Tto1 activity is suggested in the corolla.
Low and high affinity amino acid H+‐cotransporters for cellular import of neutral and charged amino acids
Authors: Fischer Wolf‐N. , Loo Donald D. F. , Koch . Wolfgang , Ludewig Uwe , Boorer Kathryn J. , Tegeder Mechthild , Rentsch Doris , Wright Ernest M. , Frommer Wolf B. 
Published: March 2003

SummaryAmides and acidic amino acids represent the major long distance transport forms of organic nitrogen. Six amino acid permeases (AAPs) fromArabidopsismediating transport of a wide spectrum of amino acids were isolated. AAPs are distantly related to plasma membrane amino acid transport systems N and A and to vesicular transporters such as VGAT from mammals. A detailed comparison of the properties by electrophysiology after heterologous expression inXenopusoocytes shows that, although capable of recognizing and transporting a wide spectrum of amino acids, individual AAPs differ with respect to specificity. Apparent substrate affinities are influenced by structure and net charge and vary by three orders of magnitude. AAPs mediate cotransport of neutral amino acids with one proton. Uncharged forms of acidic and basic amino acids are cotransported with one proton. Since all AAPs are differentially expressed, different tissues may be supplied with a different spectrum of amino acids. AAP3 and AAP5 are the only transporters mediating efficient transport of the basic amino acids.In vivocompetition shows that the capability to transport basic amino acidsin plantamight be overruled by excess amides and acidic amino acids in the apoplasm. With the exception of AAP6, AAPs do not recognize aspartate; only AAP6 has an affinity for aspartate in the physiologically relevant range. This property is due to an overall higher affinity of AAP6 for neutral and acidic amino acids. Thus AAP6 may serve a different role either in cooperating with the lower affinity systems to acquire amino acids in the low concentration range, as a system responsible for aspartate transport or as an uptake system from the xylem. In agreement, a yeast mutant deficient in acidic amino acid uptake at low aspartate concentrations was complemented only by AAP6. Taken together, the AAPs transport neutral, acidic and cationic amino acids, including the major transport forms, i.e. glutamine, asparagine and glutamate. Increasing proton concentrations strongly activate transport of amino acids. Thus the actual apoplasmic concentration of amino acids and the pH will determine what is transportedin vivo, i.e. major amino acids such as glutamine, asparagine, and glutamate will be mobilized preferentially.
Synchronous Arabidopsis suspension cultures for analysis of cell‐cycle gene activity
Authors: Menges Margit , Murray James A.H. 
Published: March 2003

SummarySynchronized suspension cultures are powerful tools in plant cell‐cycle studies. However, few Arabidopsis cell cultures are available, and synchrony extending over several sequential phases of the cell cycle has not been reported. Here we describe the first useful synchrony in Arabidopsis, achieved by selecting the rapidly dividing Arabidopsis cell suspensions MM1 and MM2d. Synchrony may be achieved either by removing and re‐supplying sucrose to the growth media or by applying an aphidicolin block/release. Synchronization with aphidicolin produced up to 80% S‐phase cells and up to 92% G2 cells, together with clear separation of different cell‐cycle phases. These synchronization procedures can be used for analysis of gene expression and protein activity. We show that representatives of three CDK gene classes of Arabidopsis (CDKA, CDKB1 and CDKB2) show differential expression timing, and that three CDK inhibitor genes show strikingly different expression patterns during cell‐cycle re‐entry. We propose that ICK2 (KRP2) may have a specific role in this process.
hoc: an Arabidopsis mutant overproducing cytokinins and expressing high in vitro organogenic capacity
Authors: Catterou Manuella , Dubois Frédéric , Smets Raphael , Vaniet Sébastien , Kichey Thomas , Van Onckelen Harry , Sangwan‐Norreel Brigitte S. , Sangwan Rajbir S. 
Published: March 2003

SummaryA novel Arabidopsis thaliana mutant, named hoc, was found to have an high organogenic capacity for shoot regeneration. The HOC locus may be involved in cytokinin metabolism leading to cytokinin‐overproduction. In vitro, hoc root explants develop many shoots in the absence of exogenous growth regulators. The mutant displays a bushy phenotype with supernumerary rosettes and with normal phyllotaxy, resulting from precocious axillary meristem development. Genetic and molecular analyses show that the high shoot regeneration and the bushy phenotype are controlled by a recessive single gene, located on chromosome I, next to the GAPB CAPS marker. The mapping data and allelism tests reveal that the hoc mutant is not allelic to other reported Arabidopsis growth‐regulator mutants. In darkness the hoc mutant is de‐etiolated, with a short hypocotyl, opened cotyledons and true leaves. Growth regulator assays reveal that the mutant accumulates cytokinins at about two‐ and sevenfold the cytokinin level of wild‐type plants in its aerial parts and roots, respectively. Consequently, the elevated amounts of endogenous cytokinins in hoc plants are associated with high organogenic capacity and hence bushy phenotype. Thus hoc is the first cytokinin‐overproducing Arabidopsis mutant capable of auto‐regenerating shoots without exogenous growth regulators.
Storekeeper defines a new class of plant‐specific DNA‐binding proteins and is a putative regulator of patatin expression
Authors: Zourelidou Melina , De Torres‐Zabala Marta , Smith Caroline , Bevan Michael W. 
Published: March 2003

SummaryThe expression of class I patatin genes is restricted to potato tubers but can be induced in other tissues by exogenous sucrose. Here we show that tuber‐specific and sucrose‐inducible gene expression is reduced in transgenic potato plants by mutations in a conserved 10 base pair motif within the B‐box of the patatin promoter. In a southwestern screen, we have isolated a novel DNA‐binding protein designated Storekeeper (STK) that specifically recognises the B‐box motif in vitro. Gel shift experiments with an STK‐specific antibody suggest that STK is the B‐box binding protein found in tuber nuclei. We propose that STK, the defining member of a new class of DNA binding proteins, regulates patatin expression in potato tubers via the B‐box motif.
The deposition of suberin lamellae determines the magnitude of cytosolic Ca2+ elevations in root endodermal cells subjected to cooling
Authors: Moore Catherine A. , Bowen Helen C. , Scrase‐Field Sarah , Knight Marc R. , White Philip J. 
Published: March 2003

SummaryA transient increase in cytosolic Ca2+ concentration ([Ca2+]cyt) is thought to be a prerequisite for an appropriate physiological response to both chilling and salt stress. The [Ca2+]cyt is raised by Ca2+ influx to the cytosol from the apoplast and/or intracellular stores. It has been speculated that different signals mobilise Ca2+ from different stores, but little is known about the origin(s) of the Ca2+ entering the cytosol in response to specific environmental challenges. We have utilised the developmentally regulated suberisation of endodermal cells, which is thought to prevent Ca2+ influx from the apoplast, to ascertain whether Ca2+ influx is required to increase [Ca2+]cyt in response to chilling or salt stress. Perturbations in [Ca2+]cyt were studied in transgenic Arabidopsis thaliana, expressing aequorin fused to a modified yellow fluorescent protein solely in root endodermal cells, during slow cooling of plants from 20 to 0.5°C over 5 min and in response to an acute salt stress (0.333 m NaCl). Only in endodermal cells in the apical 4 mm of the Arabidopsis root did [Ca2+]cyt increase significantly during cooling, and the magnitude of the [Ca2+]cyt elevation elicited by cooling was inversely related to the extent of suberisation of the endodermal cell layer. No [Ca2+]cyt elevations were elicited by cooling in suberised endodermal cells. This is consistent with the hypothesis that suberin lamellae isolate the endodermal cell protoplast from the apoplast and, thereby, prevent Ca2+ influx. By contrast, acute salt stress increased [Ca2+]cyt in endodermal cells throughout the root. These results suggest that [Ca2+]cyt elevations, upon slow cooling, depend absolutely on Ca2+ influx across the plasma membrane, but [Ca2+]cyt elevations in response to acute salt stress do not. They also suggest that Ca2+ release from intracellular stores contributes significantly to increasing [Ca2+]cyt upon acute salt stress.