bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transgenic tobacco plants expressing yeast‐derived invertase in either the cytosol, vacuole or apoplast: a powerful tool for studying sucrose metabolism and sink/source interactions
Authors: Sonnewald Uwe , Brauer Monika , von Schaewen Antje , Stitt Mark , Willmitzer Lothar 
Published: February 2005

SummaryIn higher plants sucrose plays a central role with respect to both short‐term storage and distribution of photoassimilates formed in the leaf. Sucrose is synthesized in the cytosol, transiently stored in the vacuole and exported via the apoplast. In order to elucidate the role of the different compartments with respect to sucrose metabolism, a yeast‐derived invertase was directed into the cytosol and vacuole of transgenic tobacco plants. This was in addition to the targeting of yeast‐derived invertase into the apoplast described previously. Vacuolar targeting was achieved by fusing an N‐terminal portion (146 amino acids long) of the vacuolar protein patatin to the coding region of the mature invertase protein.Transgenic tobacco plants expressing the yeast‐derived invertase in different subcellular compartments displayed dramatic phenotypic differences when compared to wild‐type plants. All transgenic plants showed stunted growth accompanied by reduced root formation. Starch and soluble sugars accumulated in leaves indicating that the distribution of sucrose was impaired in all cases. Expression of cytosolic yeast invertase resulted in the accumulation of starch and soluble sugars in both very young (sink) and older (source) leaves. The leaves were curved, indicating a more rapid cell expansion or cell division at the upper side of the leaf. Light‐green sectors with reduced photosynthetic activity were evenly distributed over the leaf surface. With the apoplastic and vacuolar invertase, the phenotypical changes induced only appear in older (source) leaves. The development of bleached and/or necrotic sectors was linked to the source state of a leaf. Bleaching followed the sink to source transition, starting at the rim of the leaf and moving to the base. The bleaching was paralleled by the inhibition of photosynthesis.
Characterization and localization of laccase forms in stem and cell cultures of sycamore
Authors: Driouich Azeddine , Lainé Anne‐Catherine , Vian Brigitte , Faye Loic 
Published: February 2005

SummaryA laccase‐type polyphenoloxidase (EC 1.10.3.2.), abundantly secreted by suspension‐cultured sycamore (Acer pseudoplatanus) cells was purified to homogeneity. This laccase form is a glycoprotein (molecular weight 110000) with high mannose and complex glycans. The polypeptide moiety has a molecular weight of 66 000, indicating that the glycoprotein is 40% carbohydrate. Laccase is abundantly present in both the cell wall and the culture medium of suspension‐cultured sycamore cells, but it is not detected in the cytoplasm, indicating that this large protein is efficiently secreted by the cells. Polyclonal rabbit antiserum was raised against the deglycosylated protein and was used to probe extracts of sycamore stem tissues. A second laccase form (molecular weight 56 000), antigenically related to laccase from cell cultures, is abundant in the epidermis of sycamore stems. In addition, this 56 kDa laccase form co‐localizes with lignin precursors on tissue prints from sycamore stems. A polypeptide (molecular weight 50 000‐56 000), antigenically related to sycamore laccase, was also immunodetected in most plant organs previously described in the literature as polyphenoloxidase‐rich.
Comparison of homologous recombination frequencies in somatic cells of petunia and tobacco suggest two distinct recombination pathways
Authors: Engels Peter , Meyer Peter 
Published: February 2005

SummaryHomologous recombination in plants was studied using an extrachromosomal recombination assay in which intermolecular homologous recombination between two complementary plasmids restored a selectable marker gene. Several vectors containing an insertion into or deletions within the coding region of the neomycin phosphotransferase (NPT‐II) gene were designed. Plasmids were introduced, in pairwise combinations, into protoplasts and homologous recombination events were measured by counting the number of NPT‐ll‐resistant colonies. A 10‐fold increase in recombination frequency was observed in Petunia hybrids RL01 compared to Nicotiana tabacum SRI. This difference occurred when one or both of the co‐transferred recombination plasmids was offered in a circular form. Apart from such specific differences between two cultivars from different species, a two‐to fivefold increase in recombination frequencies was observed when the genomic TBS (transformation booster sequence) fragment from P. hybrids was added onto one of the transferred plasmids. TBS‐specific stimulation of recombination was observed in Petunia RL01. These data suggest that two different recombination pathways may be present in plants.
Behaviour of the maize transposable element Ac in Arabidopsis thaliana
Authors: Dean Caroline , Sjodin Christina , Page Tania , Jones Jonathan , Lister Clare 
Published: February 2005

SummaryThe somatic and germinal activity of the maize transposable element, Ac, has been analysed in progeny of 43 transformants of A. thaliana using a streptomycin resistance assay to monitor Ac excision. The ability to assay somatic activity enabled, for the first time, a detailed analysis of Ac activity in individual A. thaliana seedlings to be made. The effects of T‐DNA copy number, generation, dosage at each locus, flanking sequences and orientation of the element were compared. The most striking observation was the variability in Ac activity in genotypically identical individuals and the poor penetrance of the variegated phenotype. In general, increasing Ac dosage increased both somatic and germinal excision frequencies. The majority of families from individuals selected as inheriting an excision event carried transposed Ac elements re‐integrated in different positions in the genome.
Parallel pathways for intracellular Ca2+ release from the vacuole of higher plants
Authors: Johannes Eva , Brosnan James M. , Sanders Dale 
Published: February 2005

SummaryA novel pathway for intracellular Ca2+ release via a voltage‐gated channel has been diered in the tonoplast of Beta vulgaris (sugar beet) tap roots. The channel is characterized electrophysiologically in isolated vacuoles and radiometrically in tonoplast‐enriched microsomes. Single channel properties were studied in excised membrane patches. With 5‐20 mM Ca2+ as a charge carrier on the vacuolar side, the unitary current saturates to a maximal value of 0.59 ± 0.05 pA as membrane voltage approaches +30 to +50 mV. The maximal slope conductance at non‐saturating voltages is 12.45 ± 1.06 pS. Open‐state probability increases markedly with positive‐going voltage changes in the physiological range. Channel activity is also increased by vacuolar, but not by cytosolic Ca2+. The lanthanide Gd3+ is alone among a large range of Ca2+ channel antagonists in acting as an effective inhibitor of the channel, primarily as a result of a dramatic effect on the open‐state probability. We conclude that this voltage‐gated channel could constitute an alternative, inositol (1,4,5)‐trisphosphate‐independent pathway for vacuolar Ca2+ release during signal transduction in plants.
In‐situ localization of chalcone synthase mRNA in pea root nodule development
Authors: Yang Wei‐Cai , Cramers Hayo C.J. Canter , Hogendijk Peter , Katinakis Panagiotis , Wijffelman Carel A. , Franssen Henk , Van Kammen Albert , Bisseling Ton 
Published: February 2005

SummaryIn this paper studies on the role of flavonoids in pea root nodule development are reported. Flavonoid synthesis was followed by localizing chalcone synthase (CHS) mRNA in infected pea roots and in root nodules. In a nodule primordium, CHS mRNA is present in all cells of the primordium. Therefore it is hypothesized that the Rhizobium Nod factor induces cell division in the root cortex by stimulating the production of flavonoids that function as auxin transport inhibitors. In nodules CHS mRNA is predominantly present in a region at the apex of the nodule consisting of meristematic and cortical cells. These cells are not infected by Rhizobium. Therefore it is postulated that CHS plays a role in nodule development rather than in a defence response. In roots CHS mRNA is located at a similar position as in nodules, suggesting that CHS has the same function in both root and nodule development.When nodules are formed by mutants of Rhizobium leguminosarum bv. viciae that are unable to secrete β(1‐2) glucan and to synthesize the O‐antigen containing LPS I, CHS genes are also expressed in regions of the nodule that are infected by Rhizobium. It is postulated that the impaired development of nodules formed by these mutants is due to an induction of a plant defence response.
Characterization of a shoot‐specific, GA3‐ and ABA‐Regulated gene from tomato
Authors: Shi Lifang , Gast Robert T. , Gopalraj Manjula , Olszewski Neil E. 
Published: February 2005

SummaryA tomato (Lycopersicon esculentum) gene (GAST1) that encodes an RNA whose abundance increases > 20‐fold in shoots of the GA‐deficient gib 1 mutant following spraying with GA3 has been characterized. An increase in GAST1 RNA levels is detectable 2 h after treatment and levels continue to increase for at least an additional 10 h. Between 12 and 24 h following treatment, the amount of GAST1 RNA begins to decline and at 48 h the level is nearly equivalent to that of water‐treated control plants. Nuclear runoff analysis indicates that 8 h after treatment with GA3, transcription of the GAST1 gene has increased only threefold, suggesting that GA acts both transcriptionally and post‐transcriptionally. ABA partially inhibits the GA‐mediated increase in GAST1 RNA abundance while ethephon, kinetin, and 2, 4‐D have little effect. GAST1 RNA is detectable in untreated leaves, stems, petioles and flowers, but not in roots. The GAST1 gene encodes a 0.7 kb transcript. The sequence of the GAST1 cDNA and genomic clones indicates that the gene is interrupted by three introns and potentially encodes a 112 amino acid protein of unknown function.
Cold‐plaque screening: a simple technique for the isolation of low abundance, differentially expressed transcripts from conventional cDNA libraries
Authors: Hodge Rachel , Paul Wyatt , Draper John , Scott Rod 
Published: February 2005

SummaryWe report here a simple method for obtaining organ‐or tissue‐specific clones from a cDNA library which are represented at low or medium abundance in the mRNA pool. An anther cDNA library has been screened for anther‐specific clones using a new technique we have called cold‐plaque screening. Using cold‐plaque screening we have confirmed the prediction that a large proportion (40%) of unique transcripts in the anther are organ‐specific but that the majority are of low abundance and therefore not identified by conventional differential screening.
Biochemical characterization of transgenic tomato plants in which carotenoid synthesis has been inhibited through the expression of antisense RNA to pTOM5
Authors: Bramley Peter , Teulieres Chantal , Blain Ian , Bird Colin , Schuch Wolfgang 
Published: February 2005

SummaryTransgenic tomato plants expressing antisense RNA to a ripening‐related cDNA clone (pTOM5) had yellow ripening fruit and pale coloured flowers. Carotenoid levels in fruit of these plants were reduced by up to 97%. In order to determine the step of carotenoid biosynthesis which was blocked, a cell‐free system active in the synthesis of carotenoid intermediates was prepared. Incubations with radiolabelled carotenoid precursors led to the identification of the block between GGDP and phytoene.Analysis of carotenoids in different tissues of transgenic and control plants indicated that although ripe fruit and flower carotenoid levels were reduced in the modified plants, leaf carotenoid levels were not decreased. This implies that the pTOM5 gene product is not involved in carotenoid synthesis in the leaf.
Bean homologs of the mammalian glucose‐regulated proteins: induction by tunicamycin and interaction with newly synthesized seed storage proteins in the endoplasmic reticulum
Authors: D'Amico Leone , Valsasina Barbara , Daminati M. Gloria , Fabbrini M. Serena , Nitti Gianpaolo , Bollini Roberto , Ceriotti Aldo , Vitale Alessandro 
Published: February 2005

SummaryTreatment of developing bean cotyledons with the inhibitor of N ‐glycosylation tunicamycin enhanced the synthesis of at least two polypeptides with molecular mass 78 kDa and 97 kDa. Pulse‐chase experiments and subcellular fractionation indicated that these are endoplasmic reticulum (ER) residents. The 78 kDa protein is a major component of the ER protein fraction and, by N‐terminal sequencing, was identified as a bean homolog of the mammalian 78 kDa glucose‐regulated protein (GRP78). This is a molecular chaperone that is probably involved in the folding and oligomerization of several animal and yeast proteins in the ER. When newly synthesized storage glyco‐proteins phaseolin, phytohemagglutinin or α‐amylase inhibitor were immunoprecipitated from an ER preparation of tunicamycin‐treated tissue, the GRP78 homolog was always co‐precipitated. Bound GRP78 homolog could be released by ATP treatment. These results suggest that, at least when glycosylation is inhibited, this protein plays a role in the early stages of the synthesis of vacuolar storage proteins.
Lotus japonicus, an autogamous, diploid legume species for classical and molecular genetics
Authors: Handberg Kurt , Stougaard Jens 
Published: February 2005

SummaryIn the Leguminosae plant family, few of the individual plant species have been used for plant molecular biology research. Among the species investigated no obvious representative ‘model’ legume has emerged. Here a member of the tribe Loteae, Lotus japonicus (Regel) Larsen is proposed as a candidate. L. japonicus is a diploid, autogamous species, with a good seed set, and a generation time of approximately 3 months. The haploid genome consists of six chromosomes and the genome size was estimated to be relatively small (0.5 pg per haploid complement). L. japonicus is susceptible to Agrobacterium tumefaciens and transgenic plants can be regenerated after hygromycin or kanamycin selection. Tissue culture conditions and procedures for transformation and regeneration are described. Stable transformation is demonstrated by segregation of the hygromycin selectable marker after selfing of transgenic plants or test crosses. The possibility of mapping polymorphic DNA markers inbred lines of L. japonicus is also discussed.
PEPC‐mediated carbon fixation in transmitting tract cells reflects style–pollen tube interactions
Authors: Jansen Marcel A.K. , Sessa Guido , Malkin Shmuel , Fluhr Robert 
Published: February 2005

SummaryStyles nurture and guide pollen tubes to the ovules. The styles of Nicotiana tabacum, a C3 plant, contain a concentric strand of transmitting tract cells replete with well‐developed chloroplasts. It is shown that the chloroplasts have normal ultrastructure and electron transport ability. However, they were found to be devoid of Rubisco, the key enzyme responsible for carbon fixation in C3 plants. Nevertheless, non‐invasive fluorescence techniques showed a light‐driven photosynthetic flux. Carbon fixation via phosphoenol pyruvate carboxylase (PEPC) into malate was demonstrated, the latter accumulating during stylar development. Characterization of stylar PEPC in vitro and in vivo revealed apparent Km values consistent with bicarbonate as a rate limiting factor for photosynthetic flux. Presumably, in the closed confines of the intact style, respired CO2 is the source of carbonate. Enhanced photosynthetic flux was detected following pollination, suggesting utilization of the additional respired bicarbonate and underlining metabolic interactions between the style and the elongating pollen tube.
RFLP markers for sugar beet breeding: chromosomal linkage maps and location of major genes for rhizomania resistance, monogermy and hypocotyl colour
Authors: Barzen E. , Mechelke W. , Ritter E. , Seitzer J. F. , Salamini F. 
Published: February 2005

SummaryAn RFLP linkage map for the nine chromosomes of sugar beet (Beta vulgaris L. ssp. vulgaris var. altissima Doell) was constructed by using a segregating population from a cross between two plants which were heterozygous for several agronomically interesting characters. One hundred and eleven RFLP loci have been mapped to nine linkage groups using 92 genomic markers. The current RFLP map covers a total length of 540 cM. Evidence for the existence of a major gene for rhizomania resistance (Rr1) is given, together with its map position on linkage group IV in the interval between loci GS44 and GS28a. The presence of an RFLP fragment at the GS3d locus is, until now, the best molecular marker for rhizomania‐resistant genotypes in segregating populations of sugar beet; GS3d is linked to Rr1 with 6.7 cM. The gene MM, controlling the polygerm/monogerm seed type, has been mapped on linkage group IX in a distal position at 4.2 cM from the locus GS7. The gene R controlling the hypocotyl colour maps to linkage group VII and does not recombine with the RFLP locus GS42. The inheritance of a group of RFLP loci revealed the possible presence of a translocation in the population used to establish the map. The data presented are discussed in relation to the possibility of using RFLP markers in sugar beet breeding.
Transformation of cereals via Agrobacterium and the pollen pathway: a critical assessment
Authors: Langridge Peter , Brettschneider Reinhold , Lazzeri Paul , Lörz Horst 
Published: February 2005

SummaryIt has been proposed that transgenic plants of cereals can be generated by inoculating florets with Agrobacterium at or near anthesis. This procedure is shown to lead to the production of embryos of wheat and barley with enhanced resistance to antibiotic selection. It has also been possible to recover plants of wheat, barley and maize that gave positive hybridization signals with probes produced from within the T‐DNA of the Agrobacterium vector. However, no evidence was found for transmission of the bands detected by hybridization in the progeny of the putative transgenic plants nor could enzyme activity associated with the resistance genes be found in plant extracts. Furthermore, undigested genomic DNA from the plants that were positive when probed with the T‐DNA, showed hybridization to bands smaller than the genomic DNA. It is suggested that the apparent transformation is an artifact of the procedure and does not reflect transformation of the plant nuclear genome.
Isolation of a maize bZIP protein subfamily: candidates for the ocs‐element transcription factor
Authors: Foley Rhonda C. , Grossman Carol , Ellis Jeff G. , Llewellyn Danny J. , Dennis Elizabeth S. , Peacock W. James , Singh Karam B. 
Published: February 2005

SummaryOcs‐elements, a family of 20 bp DNA sequences, are components of a number of promoters active in plants. In the maize BMS cell line the dominant ocs‐element binding activity is the ocs‐element transcription factor complex called OTF. The isolation of cDNA clones from a BMS cDNA expression library for two bZIP (basic region‐leucine zipper) proteins that bind the ocs‐element sequence and are good candidates for forming at least part of OTF is described. The two ocs‐element binding proteins, called OBF3.1 and OBF3.2, are closely related, with the OBF3.1 protein sharing 95.8% amino acid homology with part of the OBF3.2 protein although there were significant differences in the 3′ untranslated regions. Genomic Southern blot analysis revealed a small gene family with a minimum of two OBF3 loci mapping to chromosomes 3L 105 and 8L075. The OBF3.1 protein shared considerable homology with the wheat HBP1b protein (80% amino acid identity) and to a lesser extent with the tobacco TGA1a protein. OBF3.1 like HBP1b was able to bind well to the Hex sequence but poorly to G‐box/ABRE sequences. Interestingly, OBF3.1 bound eightfold more efficiently to an ocs‐element sequence than TGA1a, raising the possibility that OBF3.1 and TGA1a may be distinct members of an OBF3/TGA subfamily.
Construction of integrated genetic linkage maps by means of a new computer package: Join Map
Authors: Stam Piet 
Published: February 2005

SummaryA computerized procedure to construct integrated genetic maps is presented. The computer program (Join Map) can handle raw data from F2s, backcrosses and recombinant inbred lines, as well as listed pair‐wise recombination frequencies. The procedure is useful for combining linkage data that have been collected in different experiments; the result is a mathematical alignment of the distinct genetic maps. Data from single experiments can be dealt with as well. In view of the fast growing amount of linkage information for molecular markers, which is often being generated by different research groups, integrated maps provide useful information on the map position of genes and DNA markers.The procedure performs a sequential build‐up of the map and, at each step, a numerical search for the best fitting order of markers. Weighted least squares is used for the estimation of map distances.
Substrate‐dependent negative selection in plants using a bacterial cytosine deaminase gene
Authors: Stougaard Jens 
Published: February 2005

SummaryThe inability of many higher eukaryotes to convert 5‐fluorocytosine to cytotoxic 5‐fluorouracil presents the possibility of using the bacterial cytosine deaminase codA gene for negative selection. In transformed plant callus, expression of codA results in cell death on 5‐fluorocytosine. In transgenic tobacco and Lotus japonicus plants the substrate‐dependent negative marker segregates as a single dominant gene, and on 5‐fluorocytosine CodA+ seedlings stop growing at the early seedling stage. Positive selection of CodA+ tobacco on the pyrimidine biosynthetic inhibitor N‐(phosphonacetyl)‐l‐aspartate was obtained, by pyrimidine salvage from external cytosine. Activity of cytosine deaminase was determined by conversion of labelled cytosine to uracil followed by separation in thin layer chromatography. The codA marker therefore provides substrate‐dependent negative and positive selection, together with cytosine deaminase reporter activity.
Differential expression of the rol A plant oncogene and its effect on tobacco development
Authors: Carneiro Mauro , Vilaine Françoise 
Published: February 2005

SummaryThe rolA gene not only provokes the abnormal traits of wrinkled leaves, shortened internodes, and deficient root growth in tobacco, but also induction of roots in leaf disks in hormone‐free medium. The rolA mRNA is most abundant in the stem of transgenic tobacco, accumulating at fivefold and 50‐fold lower levels in the leaf and the root, respectively. Promoter deletion mutants were constructed and the rolA‐induced abnormal traits were exploited to identify promoter regulatory regions. The removal of specific promoter domains provokes the appearance of new patterns of rolA transcripts in leaves, stems and roots. These new patterns are correlated with the disappearance of specific abnormal trait, thereby identifying three functional domains. Domain A includes a mosaic motif composed of a putative GT‐2 binding site and DUE‐NDE elements. This domain positively regulates rolA gene expression in the leaf and negatively regulates it in the stem and root. Domains B and C, which contain sequences homologous to the OCS enhancer and to ASF‐1 binding sites, respectively, generally activate the rolA gene expression in all tissues. The possible function of these elements on the regulation of the rolA gene is discussed.