bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the cucumber malate synthase gene promoter by transient expression and gel retardation assays
Authors: Graham Ian A. , Baker Christopher J. , Leaver Christopher J. 
Published: March 2003

SummaryRecently it has been demonstrated that the single‐copy malate synthase (MS) and isocitrate lyase (ICL) genes from cucumber are regulated by nutritional status in cucumber cell cultures. In this paper a new cucumber mesophyll protoplast transient expression system is described in which electroporated MS promoter—GUS reporter gene constructs exhibit the same pattern of expression as the endogenous MS gene. Both the electroporated MS—GUS constructs and the endogenous gene are expressed when protoplasts are cultured for 48 h on a non‐metabolizable carbon source such as mannitol or 3‐methylglucose, and repressed when cultured on a utilizable carbon source such as sucrose, glucose or fructose. A series of deletion mutants identified a region from position −248 to −125 relative to the start of transcription that is essential for expression of the MS—GUS construct under the different metabolic conditions. A 191 bp fragment spanning this region was fused, in both orientations, to the CaMV 35S core promoter. A pattern of metabolic regulation similar to that of the intact MS promoter was observed for these promoter fusion constructs which strongly suggests the presence of enhancer element(s) within this region. Comparison of the 191 bp region with other MS and ICL promoter sequences revealed a region of homology, designated RT. A gel retardation assay was used to assess binding of the 191 bp fragment to whole cell protein extracts from cell cultures expressing MS. Both the unlabelled 191 bp fragment and a synthetic oligonucleotide of RT compete specifically for the demonstrated binding activity.
GCAC1 recognizes the pH gradient across the plasma membrane: a pH‐sensitive and ATP‐dependent anion channel links guard cell membrane potential to acid and energy metabolism
Authors: Schulz‐Lessdorf Barbara , Lohse Gabi , Hedrich Rainer 
Published: March 2003

SummaryIon channels in the plasma membrane of guard cells provide key mechanisms in signal perception and volume regulation during stomatal movement. Recent studies have suggested that the strongly voltage‐dependent, inactivating guard cell anion channel (GCAC1) acts as a sensor of the ambient extracellular CO2 concentration and as a target of modulation by nucleotides and Ca2+ ions. Applying the patch‐clamp technique it is demonstrated here that GCAC1 is activated by cytoplasmic ATP in a pH‐dependent manner.When the apoplastic pH was buffered to 5.6 and the cytosolic pH dropped step‐wise from 7.8 to 5.6, the single‐channel activity increased as a function of proton concentration. This pH‐sensitivity is characterized by a titratable site with an apparent pK value around 6.9. While the steepness and direction of the transmembrane pH gradient did not affect the kinetics of activation, deactivation and fast inactivation of the whole‐cell anion current, the kinetics of slow inactivation and reactivation were strongly influenced. When at a constant intracellular proton concentration of pH 7.2 the external pH decreased from 7.2 to 5.6 the time constants of slow inactivation and the half‐times of reactivation increased two‐ and sevenfold, respectively.The mechanism of nucleotide activation of GCAC1 was quantitatively analysed on the level of single‐channel events. Using inside‐out, cell‐free membrane patches, GCAC1 half‐activated around 0.4 mM ATP. The sigmoidal dose‐dependence of anion channel activation could be well fitted with an apparent Hill coefficient of 3.6. This behaviour might indicate that the activation process involves a strongly cooperative interaction of four ATP‐binding sites. Neither ATP nor its non‐hydrolysable analogue AMP‐PMP, which also activated GCAC1, altered the voltage‐dependent gating. AMP‐PMP stimulation and the insensitivity of GCAC1 towards the phosphatase inhibitor, okadaic acid, and the kinase inhibitors, staurosporine and H‐7, provided evidence that nucleotide binding rather than phosphorylation caused channel activation.Since the time‐ and voltage‐dependent activity of GCAC1 is strongly modulated by ATP and protons, this channel is capable of sensing changes in the energy status, acid metabolism and the H+ ATPase activity of guard cells.
Correlation between activities of starch debranching enzyme and α‐polyglucan structure in endosperms of sugary‐1 mutants of rice
Authors: Nakamura Yasunori , Kubo Akiko , Shimamune Tomoyuki , Matsuda Toshiaki , Harada Kyuya , Satoh Hikaru 
Published: March 2003

SummaryThe biochemical lesion of the sugary‐1 mutation was examined in five different mutants of rice with varying phenotypes but with mutations at the same locus. The cells in the inner part of the endosperm of all mutants tested contained phytoglycogen instead of starch, while the cells located in the outer part of the endosperm tissue from some mutants were filled with numerous starch granules. The molecular size of phytoglycogen was markedly smaller than that of amylopectin as measured by Sephacryl S‐1000 chromatography. Analysis of the distribution of α‐1,4 chain lengths revealed that in phytoglycogen the number of A‐chains dramatically increased, while long B chains with DP ≥ 37 remarkably decreased or were almost absent, which resulted in the disappearance of the cluster structure. The results suggest that changes in the balance of enzymic activities induced by the mutations brought about a drastic alteration in polyglucan structure and the shape of the polyglucan granule. The greater the extent of phytoglycogen regions in su1 endosperm tissues became, the greater was the phytoglycogen content, and the greater the reduction in the activity of starch debranching enzyme, a type of enzyme referred to as R‐enzyme (RE), limit dextrinase or pullulanase. Immunoblot analysis showed that the reduction in RE activity was due to a decrease in the amount of RE protein, and that the reduction in RE was specific since proteins of starch‐branching enzymes I and IIa and ADP‐glucose pyrophosphorylase were not markedly affected by su1 mutations. The proportion of starch region to the whole endosperm tissue of various su1 mutants was correlated with the RE activity in these endosperms. The results strongly suggest that the reduction in RE activity is involved in the su1 phenotype and that the enzyme plays an essential role in determining the fine structure of the amylopectin molecule
Two TIP‐like genes encoding aquaporins are expressed in sunflower guard cells
Authors: Sarda X. , Tousch D. , Ferrare K. , Legrand E. , Dupuis J.M. , Casse‐Delbart F. , Lamaze T. 
Published: March 2003

SummarySunTIP7 and SunTIP20 are closely related sunflower cDNAs showing a deduced amino acid sequence homologous to proteins of the tonoplast intrinsic protein (TIP) family. Their expression in Xenopus oocytes caused a marked increase in osmotic water permeability (demonstrating that they are water channels) which was sensitive to mercury. In leaves, in situ hybridization revealed that both SunTIP7 and SunTIP20 mRNA accumulated in the guard cells. The possible involvement of SunTIPs in stomatal movement was examined by comparing the time course of transcript accumulation and leaf conductance during the daily cycle and following a water limitation. SunTIP7 mRNA fluctuations fitted changes occurring in leaf conductance. The transcript levels were markedly and systematically increased during stomatal closure. It is suggested that aquaporin SunTIP7 facilitates water exit associated with a decrease in guard cell volume. In the same conditions, the transcript level of SunTIP20 remained constant indicating that SunTIP genes are differentially regulated within the same cell.
AtLTP1 luciferase expression during carrot somatic embryogenesis
Authors: Toonen Marcel A.J. , Verhees John A. , Schmidt Ed D.L. , Van Kammen Ab , De Vries Sacco C. 
Published: March 2003

SummaryThe carrot (Daucus carota L.) EP2 gene encodes a Lipid Transfer Protein (LTP) which is expressed during protoderm formation in developing embryos. To develop a vital reporter system for gene expression during somatic embryo development a 1.1 kB fragment of the Arabidopsis thaliana LTP1 promoter was fused to the firefly luciferase (LUC) coding sequence. The AtLTP1 luciferase expression pattern in transformed carrot suspension cultures was identical to the expression pattern of the endogenous carrot EP2 gene. Cell tracking experiments revealed that all somatic embryos were derived from AtLTP1 luciferase expressing cell clusters. However, not all cell clusters that expressed the AtLTP1 luciferase reporter gene developed into a somatic embryo, suggesting that initiation of an embryogenic pathway in tissue culture does not always lead to development of a somatic embryo.
Drought‐ and wound‐induced expression in leaves of a gene encoding a chromoplast carotenoid‐associated protein
Authors: Chen Hsu‐Ching , Klein Annelyse , Xiang Minghui , Backhaus Ralph A. , Kuntz Marcel 
Published: March 2003

SummaryA study has been carried out to investigate the regulation of the fibrillin (fib) gene, along with two carotenoid biosynthesis genes, namely those encoding geranylgeranyl pyrophosphate synthase (ggpps) and capsanthin‐capsorubin synthase (ccs) from bell pepper (Capsicum annuum), whose expression is greatly induced during fruit ripening. A homologous transient expression assay has shown that high expression of these genes in pepper fruit is regulated essentially at the transcriptional level. Transcription of ccs is mainly fruit‐specific and that of ggpps is highly induced in fruits. Expression of fib is more complex: it is induced not only by a developmental process in fruits but also, in pepper and tobacco leaves, by diverse environmental factors such as drought and mechanical wounding. The wound‐induced transcriptional activation of fib is light‐ and oxygen‐dependent. Evidence is provided for the involvement of superoxide anion production within plastids in the signalling pathway leading to induction of this nuclear gene by environmental stresses. Specific activation of this promoter in roots, but not in leaves, was also observed upon exogenous abscisic acid treatment. Drought or wounding also leads to the accumulation of the fibrillin polypeptide in leaves. Furthermore, a low level of fibrillin has also been detected in the leaves of non‐stressed plants. Taken together, our data suggest a general role for fibrillin in various plastid types and in response to environmental stresses, in addition to its function in assembly of carotenoid‐containing fibrils in chromoplasts.
A response‐regulator homologue possibly involved in nitrogen signal transduction mediated by cytokinin in maize
Authors: Sakakibara Hitoshi , Suzuki Megumi , Takei Kentaro , Deji Atsushi , Taniguchi Mitsutaka , Sugiyama Tatsuo 
Published: March 2003

SummaryA cDNA clone, pZmCip1, encoding a maize (Zea mays) cytokinin‐inducible protein 1 was isolated utilizing the differential display technique, and studied using the expression of ZmCip1 in nitrogen‐starved maize plants. The cloned cDNA contained an open reading frame consisting of 157 amino acids with a predicted molecular mass of 16.7 kDa, which possesses similarity with the response‐regulators of bacterial two‐component signalling systems. In detached leaves, accumulation of ZmCip1 transcript by t‐zeatin was dose‐dependent in a range of 10–9 M to 10–7 M, and occurred within 30 min after treatment. The effect of t‐zeatin was replaceable by isopentenyladenosine or isopentenyl‐adenosine‐5′‐monophosphate. Pretreatment of detached leaves with cycloheximide did not inhibit the accumulation of the transcript. In whole plants, ZmCip1 transcript was transiently accumulated exclusively in leaves by supply of nitrate or ammonium ions to the roots, whereas the transcript was not accumulated in detached leaves by supply of the nitrogen nutrients. Both the cytokinin‐ and nitrate‐responsive accumulations of ZmCip1 transcript were accompanied by an increase in the immunotitratable protein. Isopentenyladenosine and/or its phosphorylated form(s) accumulated in roots 2 h after supply of nitrate to plants. These results, taken together, suggest that ZmCip1 is a primary response gene to cytokinins, and that it involves, at least in part, the nitrogen‐signal transduction mediated by cytokinin in maize.
Induced systemic resistance in wounded rice plants
Authors: Schweizer Patrick , Buchala Antony , Dudler Robert , Métraux Jean‐Pierre 
Published: March 2003

SummaryWounding of one leaf of young rice plants caused a strong and transient accumulation of non‐conjugated (–)‐JA, followed by induction of a number of pathogenesis‐related genes, in the treated leaf. The non‐treated leaf of wounded plants that emerged after the treatment was more resistant to challenge infection by the rice blast fungus Magnaporthe grisea (Hebert) Barr. The systemic leaf also showed a transient, but delayed accumulation of jasmonic acid. Unlike the wounded leaf, there was no accumulation of pathogenesis‐related mRNAs or proteins in the systemically protected leaf. Local application of jasmonic acid, the putative signal of the wound response, resulted in a similar degree of systemic disease resistance as wounding. The results suggest the operation of systemic, wound‐related signalling processes in rice that induce systemic disease resistance.
A YAC contig map of Arabidopsis thaliana chromosome 3
Authors: Camilleri Christine , Lafleuriel Jacqueline , Macadré Catherine , Varoquaux Fabrice , Parmentier Yves , Picard Georges , Caboche Michel , Bouchez David 
Published: March 2003

SummaryWe have constructed a YAC contig map of Arabidopsis thaliana chromosome 3. From an estimated total size of 25 Mb, about 21 Mb were covered by 148 clones arranged into nine YAC contigs, which represented most of the low‐copy regions of the chromosome. YAC clones were anchored with 259 molecular markers, including 111 for which linkage information was previously available. Most of the genetic map was included in the YAC coverage, and more than 60% of the genetic markers from the reference recombinant inbred line map were anchored, giving a high level of integration between the genetic and physical maps. The submetacentric structure of the chromosome was confirmed by physical data; 3R (the top arm of the linkage map) was about 12 Mb, and 3L (the bottom arm of the linkage map) was about 9 Mb. This YAC physical map will aid in chromosome walking experiments and provide a framework for large‐scale DNA sequencing of chromosome 3.
Association of γ‐tubulin with kinetochore/centromeric region of plant chromosomes
Authors: Binarová Pavla , Hause Bettina , Doležel Jaroslav , Dráber Pavel 
Published: March 2003

SummaryMonoclonal antibodies raised against a phylogenetically conserved peptide from the C‐terminal domain of γ‐tubulin molecule were used for immunofluorescence detection of γ‐tubulin in acentriolar mitotic spindles of plant cells. The antibodies stained kinetochore fibres along their whole length, including the close vicinity of kinetochores. After microtubule disassembly by the antimicrotubular drugs amiprophos‐methyl, oryzalin and colchicine, γ‐tubulin was found on remnants of kinetochore fibres attached to chromosomes. In cells recovering from the amiprophos‐methyl treatment, γ‐tubulin was localized with the re‐growing kinetochore microtubule fibres nucleated or captured by kinetochore/centromeric regions. On isolated chromosomes, γ‐tubulin co‐localized with α‐tubulin in the kinetochore/centromeric region. The data presented suggest that in acentriolar higher plant cells γ‐tubulin might be directly or indirectly involved in modulation and/or stabilization of kinetochore–microtubule interactions.
Expression of the Arabidopsisabi1–1mutant allele inhibits proteinase inhibitor wound‐induction in tomato
Authors: Carrera Esther , Prat Salomé 
Published: March 2003

Summary Abscisic acid (ABA) is an essential component in the wound signalling cascade. Increased levels of endogenous ABA were observed after wounding and shown to be a requisite for wound‐induced expression of the proteinase inhibitor II genes. We have taken advantage of the dominant character of the Arabidopsis

abi1–1

mutation, to investigate whether ABI1 has a function in ABA signalling in response to wounding. Transgenic tomato plants carrying copies of either the wild‐type

ABI1

or the mutant

abi1–1

alleles were obtained and assayed for wound‐induction of the

pin2

or

LAP

genes. While normal levels of gene induction were observed in the transgenic

ABI1

plants, the

abi1–1

transformants displayed a severe wilty phenotype and reduced seed dormancy. Expression of the

abi1–1

dominant mutation blocked accumulation of the drought‐induced

TAS14

and

LE25

mRNAs in response to ABA, as well as ABA‐ and wound‐induced expression of the defense‐associated

pin2

and

LAP

transcripts. MeJA‐induction of the

pin2

and

LAP

mRNAs, on the contrary, was not affected in the

abi1–1

transformants. These results indicate that

abi1–1

inhibits wound‐induced expression of the

pin2

and

LAP

transcripts by blocking ABA‐induction of these genes. This implicates ABI1 in wound‐signalling and suggests that a common early ABA signalling pathway may function in the responses to wounding and water stress.
Towards functional characterisation of the members of theR2R3‐MYBgene family fromArabidopsis thaliana
Authors: Kranz Harald D. , Denekamp Marten , Greco Raffaella , Jin Hailing , Leyva Antonio , Meissner Ruth C. , Petroni Katia , Urzainqui Ana , Bevan Michael , Martin Cathie , Smeekens Sjef , Tonelli Chiara , Paz‐Ares Javier , Weisshaar Bernd 
Published: March 2003

Summary Transcription factors containing a conserved DNA‐binding domain similar to that of the proto‐oncogene

c‐myb

have been identified in nearly all eukaryotes. MYB‐related proteins from plants generally contain two related helix‐turn‐helix motifs, the R2 and R3 repeats. It was estimated that

Arabidopsis thaliana

contains more than 100

R2R3‐MYB

genes. The few cases where functional data are available suggest an important role of these genes in the regulation of secondary metabolism, the control of cell shape, disease resistance, and hormone responses. To determine the full regulatory potential of this large family of regulatory genes, a systematic search for the function of all genes of this family was initiated

.

Sequence data for more than 90 different

A. thaliana R2R3‐MYB

genes have been obtained. Sequence comparison revealed conserved amino acid motifs shared by subgroups of

R2R3‐MYB

genes in addition to the characteristic DNA‐binding domain. No significant clustering of the genes was detected, although they are not uniformly distributed throughout the

A. thaliana

genome.

R2R3‐MYB

gene expression levels were determined under more than 20 different growth conditions including hormone treatment, infection with pathogens and various stress conditions.

MYB

genes are specifically expressed in different tissues and physiological conditions, indicating the potential for involvement in various regulatory processes. The sequence and expression data together with the map positions of nearly all

MYB

genes in

A. thaliana

provide a substantial basis for further studies of this important group of transcription factors.
Early post‐embryonic root formation is specifically affected in the maize mutantlrt1
Authors: Hochholdinger Frank , Feix Günter 
Published: March 2003

Summary The isolation and detailed characterisation of the maize mutant

lrt1

, which is completely deficient in the initiation of lateral roots at the primary and seminal lateral roots and of the crown roots at the coleoptilar node is described. The monogenic and recessive mutant was isolated from a segregating EMS mutagenised population, maps to the short arm of chromosome 2, and acts independently of the nodal root deficient

rtcs

locus. Histological analysis revealed that the mutation acts at a very early stage of root initiation, as indicated by the absence of primordia formation in the affected roots. At later stages of plant development lateral and crown root initiations recover leading to fertile plants. If grown in the dark, the mutant does not form an elongated mesocotyl, although the photomorphogenic response appears to be normal in the mutant. Furthermore, the wild‐type cannot be rescued from mutants by the application of auxin to germinating kernels. The gene impaired in

lrt1

seems to be of great importance for the general mechanism of early post‐embryonic root initiation, both from root and nodal tissues, since lateral and crown root initiation are both affected to the same extent and in the same transient time pattern.
NADH oxidase activity of soybean plasma membranes oscillates with a temperature compensated period of 24 min
Authors: Morré D. James , Morré Dorothy M. 
Published: March 2003

Summary The enzymatic activity of a hormone‐stimulated and growth‐related protein disulfide‐thiol oxidoreductase (NADH oxidase) with protein disulfide‐thiol interchange activity of etiolated hypocotyls of soybean oscillates with a period of about 24 min or 60 times per 24 h day. The oscillations were temperature compensated such that the period remained constant at about 24 min between 17 and 37°C, a temperature range over which enzymatic activity varied approximately fourfold (Q10 of 2). The oscillations were observed with intact tissue sections, with isolated plasma membrane vesicles, and with the detergent‐solubilized and partially purified enzyme. The oscillations were observed both with the oxidation of NADH and in the restoration of activity to scrambled ribonuclease used as a measure of the protein disulfide‐thiol interchange activity. The enzymatic activity which is located at the cell surface may represent a biochemical reaction with a potential function as an ultradian oscillator of circadian time keeping.
Low temperature regulation of theArabidopsisCBF family of AP2 transcriptional activators as an early step in cold‐inducedCORgene expression
Authors: Gilmour Sarah J. , Zarka Daniel G. , Stockinger Eric J. , Salazar Maite P. , Houghton Jaimie M. , Thomashow Michael F. 
Published: March 2003

Summary Cold‐induced expression of the

Arabidopsis COR

(cold‐regulated) genes is mediated by a DNA regulatory element termed the CRT (C‐repeat)/DRE (dehydration‐responsive element). Recently, we identified a transcriptional activator, CBF1, that binds to the CRT/DRE and demonstrated that its overexpression in transgenic

Arabidopsis
plants at non‐acclimating temperatures inducesCORgene expression and increases plant freezing tolerance. Here we report that CBF1 belongs to a small family of closely related proteins which includes CBF2 and CBF3. DNA sequencing of an 8.7 kb region of theArabidopsisgenome along with genetic mapping experiments indicated that the threeCBFgenes are organized in direct repeat on chromosome 4 at 72.8 cM, closely linked to molecular markers PG11 and m600. Like CBF1, both CBF2 and CBF3 activated expression of reporter genes in yeast that contained the CRT/DRE as an upstream activator sequence. The transcript levels for all threeCBFgenes increased within 15 min of transferring plants to low temperature, followed by accumulation ofCORgene transcripts at about 2 h.CBFtranscripts also accumulated rapidly in response to mechanical agitation. The promoter regions of theCBFgenes do not contain the CRT sequence, CCGAC, and overexpression ofCBF1did not have a detectable effect onCBF3transcript levels, suggesting that theCBFgene family is not subject to autoregulation. We propose that cold‐induced expression of CRT/DRE‐containingCORgenes involves a low temperaturestimulated signalling cascade in whichCBFgene induction is an early event.