bluuebunny/crossref_metadata_2025_split huggingface dataset:
The GURKE gene is required for normal organization of the apical region in the Arabidopsis embryo
Authors: Torres‐Ruiz Ramón A. , Lohner Andrea , Jürgens Gerd 
Published: March 2003

SummaryDicot plant embryos undergo a transition from radial to bilateral symmetry. In Arabidopsis, this change reflects patterning within the apical region, resulting in the formation of the cotyledon and shoot meristem primordia. Mutations in the GURKE gene give seedlings with highly reduced or no cotyledons. Both strong and weak gurke alleles confer this phenotypic variability although strong alleles often eliminate the entire apex and sometimes also part of the hypocotyl. The root and the root meristem as well as the radial pattern of concentric tissue layers are essentially normal. The mutant seedling phenotype can be traced back to the triangular/early‐heart stage of embryogenesis when abnormal cell divisions occur within the apical region such that no or only rudimentary cotyledon primordia are established. The postembryonic development of gurke seedlings was examined in culture. In weak alleles, apical growth gave rise to abnormal leaves and stem‐like structures and, eventually, abnormal flowers. In strong alleles, the apical region often failed to grow but occasionally produced fused leaf‐like structures with no dorso‐ventral polarity and a totally unorganized vascular system while no stems developed. The observations suggest that the GURKE gene is involved primarily in the organization of the apical region in the embryo and may also play a role during postembryonic development.
Characterization of anther‐expressed genes encoding a major class of extracellular oleosin‐like proteins in the pollen coat of Brassicaceae†
Authors: Ross Joanne H.E. , Murphy Denis J. 
Published: March 2003

SummaryA large, heterogeneous, highly expressed gene family encoding oleosin‐like proteins is described in the Brassicaceae. íeven related cDNA sequences were isolated from Brassica napus anther mRNA using RACE‐PCR and compared with other recently described anther‐specific oleosin‐like genes from B. napus. The expression patterns of four representative members of this diverse gene family were analyzed by Northern blotting and in situ hybridization. In all cases, the genes were expressed specifically in the tapetum of 3–5 mm B. napus buds, which contained microspores at the late‐vacuolate and bicellular stages of development. The predicted protein products are ordered into subclasses, each of which has a characteristic C‐terminal domain, containing different amino acid motifs or repeated residues. Tryphine (pollen coat) fractions from mature B. napus pollen were found to be particularly enriched in polypeptides of apparent molecular weights 32–38 kDa, plus numerous less abundant polypeptides of less than 15 kDa. The N‐terminal 15–20 residues of three of these polypeptides (12, 32 and 38 kDa) were found by microsequencing to be identical to parts of the predicted amino acid sequences of three of the tapetal‐expressed oleosin‐like genes. This indicates the possibility of post‐translational modification of these proteins resulting in a cleavage of the primary translation products in order to generate the mature tryphine polypeptides. These data imply that a large and diverse group of oleosin‐like proteins is synthesized in the tapeturn of B. napus anthers and that following tapetal degradation, these proteins, possibly in modified form, then relocate to the developing microspores where they eventually constitute some of the major components of the extracellular tryphine of mature pollen grains. These proteins share a conserved 70 amino acid residue hydrophobic domain and are related structurally to the seed‐specific intracellular oleosins, although their biological function may be different.
Expression of ACC oxidase promoter—GUS fusions in tomato and Nicotiana plumbaginifolia regulated by developmental and environmental stimuli
Authors: Blume Beatrix , Grierson Donald 
Published: March 2003

SummaryThe enzyme ACC oxidase, catalysing the last step in the biosynthesis of the plant hormone ethylene, is encoded by a small multigene family in tomato, comprising three members, LEACO1, LEACO2 and LEACO3. LEACO1 is the major gene expressed during ripening, leaf senescence, and wounding (Barry et al., 1996). To investigate the transcriptional regulation of ACC oxidase gene expression, chimeric fusions between the β‐glucuronidase reporter gene and 97 bp of 5′ UTR plus 124, 396 and 1825 bp, respectively, of 5′ untranscribed LEACO1 sequence were constructed and introduced into Lycopersicon esculentum (Mill cv. Ailsa Craig) and Nicotiana plumbaginifolia. Analysis of transgenic tomatoes indicated that the region containing nucleotides −124 to +97 of the LEACO1 gene is sufficient to confer a marked increase in GUS activity during fruit ripening, albeit at very low levels. Fusion of 396 and 1825 bp of LEACO1 upstream sequence resulted in strong and specific induction of GUS expression in situations known to be accompanied by enhanced ethylene production. Reporter gene expression was similar to that of the endogenous LEACO1 gene, with major increases especially during fruit ripening, senescence and abscission of leaves and, to a lesser extent, of flowers. Analysis of transgenic N. plumbaginifolia plants confirmed the pattern of LEACO1 promoter activity detected in tomato leaves and flowers. Reporter gene expression was also induced following wounding, treatment with ethylene, and pathogen infection. Histochemical analysis illustrated localized GUS activity in the pericarp of ripening fruit, abscission zones of senescent petioles and unfertilized flowers, and at wound sites. These results demonstrate that ACC oxidase is regulated at the transcriptional level in a wide range of cell types at different developmental stages and in response to several external stimuli.
The maize actin‐depolymerizing factor, ZmADF3, redistributes to the growing tip of elongating root hairs and can be induced to translocate into the nucleus with actin
Authors: Jiang Chang‐Jie , Weeds Alan G. , Hussey Patrick J. 
Published: March 2003

SummaryThe maize actin depolymerizing factor, ZmADF3, binds G‐and F‐actin, and increases in vitro actin dynamics. Polyclonal antibodies have been raised against ZmADF3 and these detect a single band of approximately 17 kDa in all maize tissues examined, with the exception of pollen. In the development of root hairs, the distribution of ZmADF3 is related to actin reorganization. In the early stages of hair development, ZmADF3 is distributed throughout the cytoplasm. As the hair emerges and the microfilament bundles redirect to the outgrowth there is a simultaneous redistribution of ZmADF3 which now concentrates at the tip of the emerging hair and remains in this position as elongation proceeds. These observations show that ZmADF3 localizes to a region where actin is being remodelled during tip growth. After cytochalasin D treatment which disrupts actin filaments, short rods of ZmADF3 and actin appear in the nucleus suggesting that ZmADF3 may function by guiding actin to sites of actin polymerization.
Two different modes of early development and nitrogen assimilation in gymnosperm seedlings†
Authors: García‐Gutiérrez Angel , Dubois Frédéric , Cantón Francisco R. , Gallardo Fernando , Sangwan Rajbir S. , Cánovas Francisco M. 
Published: March 2003

SummaryLight‐independent chloroplast development and expression of genes encoding chloroplast proteins occur in many but not all species of gymnosperms. Early development in maritime pine (Pinus pinaster) seedlings was strongly light‐independent, whereas Ginkgo biloba seedlings exhibited a typical angiosperm‐like morphogenesis with differentiated patterns in light and dark. In pine, chloroplast polypeptides were undetectable in the seed embryo and accumulated in cotyledons of both light‐ and dark‐grown plants in good correlation with light‐independent chlorophyll synthesis. In contrast, chlorophyll and chloroplast proteins were only detected in light‐grown ginkgo. Pine cytosolic glutamine synthetase (GS) and ferredoxin glutamate synthase (Fd‐GOGAT) were present at low levels in the seeds and accumulated at comparable amounts in light‐ and dark‐grown seedlings. Fd‐GOGAT was also barely detectable in the seeds of ginkgo and only accumulated in green plants with mature chloroplasts. In G. biloba seeds and etiolated plants only cytosolic GS was identified, while in light‐grown seedlings this molecular form was present at low abundance and choroplastic GS was the predominant isoenzyme. The above results have been confirmed by immunolocalization of GS protein in pine and ginkgo plantlets. In pine, GS was present in the peripheral cytoplasm of mesophyll cells and also in the phloem region of the vascular bundle. Immunocytochemical analysis showed that the labelling of mesophyll and phloem cells was only cytoplasmic. In developing ginkgo, GS antigens were present in the chloroplasts of mesophyll parenchyma cells of leaflets and green cotyledons. In contrast, a weak labelling of GS was observed in the parenchyma and phloem cells of non‐green cotyledons enclosed in the seed coat. Taking all this into account, our data indicate the existence of two different modes of GS and GOGAT regulation in gymnosperms in close correlation with the differential response of plants to light. Furthermore, the results suggest that glutamine and glutamate biosynthesis is confined to the chloroplast of mesophyll cells in species with light‐dependent chloroplast, development whereas compartmentation would be required in species with light‐independent plastid development.
The action potential in Chara: Ca2+ release from internal stores visualized by Mn2+‐induced quenching of fura‐dextran
Authors: Plieth Christoph , Sattelmacher Burkhard , Hansen Ulf‐Peter , Thiel Gerhard 
Published: March 2003

SummaryThe action potential (AP) in Chara is associated with a transient elevation in the concentration of cytoplasmic‐free Ca2+ ([Ca2+]cyt). The quenching properties of the fluorescent Ca2+ indicator dye fura‐dextran, in combination with Mn2+, was used to investigate whether this [Ca2+]cyt transient is due to Ca2+ release from internal stores or to Ca2+ influx across the plasma membrane. Adding Mn2+ to the external medium or pre‐injection of Mn2+ into the vacuole caused no perceivable quenching of the fura fluorescence, during an AP. This makes it unlikely that Ca2+ influx across the plasma membrane or the tonoplast contributes significantly to the [Ca2+]cyt transient in an excited cell. When cells were pre‐incubated in external solutions containing Mn2+ from 25 to 30 mM APs evoked a transient quenching of fura fluorescence in Mn2+‐free solutions. Under these conditions, the quenching must be attributed to an AP‐associated release of Mn2+ from internal stores. Based on the finding that exposing cells to millimolar concentrations of Mn2+ caused a progressive quenching of the fura fluorescence in non‐excited cells, it can be assumed that some Mn2+ enters the cells during pre‐incubation and is loaded into internal stores. During excitation, this stored Mn2+ is released together with Ca2+.
Arginine decarboxylase (polyamine synthesis) mutants of Arabidopsis thaliana exhibit altered root growth
Authors: Watson Mark B. , Emory Kimberly K. , Piatak Ruth Marie , Malmberg Russell L. 
Published: March 2003

SummaryPutrescine and polyamines are produced by two alternative pathways in plants. One pathway starts with the enzyme arginine decarboxylase; the other with ornithine decarboxylase. The authors developed an in vivo screening strategy to identify mutants with low levels of arginine decarboxylase activity. The screen requires both a primary screen of the M2 generation and a secondary screen of the M3 generation. The method used was to screen 15 000 EMS‐mutagenized M2 seedlings for low levels of arginine decarboxylase (ADC) activity and identified seven mutants that fall into two complementation groups. These mutants have from 20% to 50% of wild‐type enzyme activity. Morphological alterations common among the mutants include increased levels of lateral root branching. The authors obtained a double mutant combining the alleles with the lowest activities from the two complementation groups; this has lower ADC enzyme activity and putrescine levels than either of the single mutants. The double mutant has highly kinked roots that form a tight cluster; it also has narrower leaves, sepals, and petals than either single mutant or wild‐type, and delayed flowering. These results suggest there may be more than one ADC gene in Arabidopsis, and that ADC and polyamine levels play roles in root meristem function and in lateral growth of leaf‐homolog organs.
Distinct patterns of pigment suppression are produced by allelic sense and antisense chalcone synthase transgenes in petunia flowers
Authors: Que Qiudeng , Wang Huai‐Yu , Jorgensen Richard A. 
Published: March 2003

SummaryA single‐copy sense Chalcone synthase (Chs) transgene driven by a strong promoter and producing a fully translatable transcript was converted to an allelic antisense Chs transgene by Cre‐lox‐mediated DNA recombination in petunia. The sense Chs allele suppressed flower pigmentation in a simple pattern determined by cells at the junctions between adjacent petals, as is typical of single‐copy sense Chs transgenes of this type, whereas the antisense Chs allele produced a different pattern of Chs suppression with white petal edges and reduced pigmentation throughout the petal limbs, as is typical of antisense Chs transgenes. In plants carrying a lox‐flanked Chs transgene, the presence of Cre protein can cause both sense‐specific and antisense‐specific patterns to be superimposed in the same flower, suggesting that sense and antisense suppression by single‐copy transgenes are mediated by different mechanisms or occur in different cellular or developmental compartments. The presence of Cre also causes the production of numerous, non‐clonal white spots, suggesting that the turnover state is not cell‐autonomous.
Chitinase in cucumber hypocotyls is induced by germinating fungal spores and by fungal elicitor in synergism with inducers of acquired resistance
Authors: Kästner Bärbel , Tenhaken Raimund , Kauss Heinrich 
Published: March 2003

SummaryAfter root pretreatment with 2,6‐dichloroisonicotinic acid (DCIA or INA), hypocotyls of etiolated cucumber seedlings acquired resistance to infection by Colletotrichum lagenarium caused by the failure of the fungus to penetrate epidermal cell walls. The hypocotyls contained only low levels of class III chitinase and its mRNA prior to infection. This pathogenesis‐related (PR) gene was expressed strongly upon infection but only in resistant hypocotyls and soon after germination of the fungal spores. Chitinase was also induced early by an albino mutant strain of C. lagenarium that can barely penetrate the epidermis. Thus, early recognition of the fungus implies signal compounds able to pass, or being generated in, the hydrophobic epidermal surface. As the apoplastic chitinase accumulates timely at the site of a subsequent attack, it may contribute to disease resistance. The mechanism behind the enhanced responsiveness of epidermal cells was studied by gently abrading the cuticle of susceptible hypocotyls to allow permeation of a water‐soluble polymeric fungal elicitor. Induction of chitinase occurred only when the elicitor was applied simultaneously with a resistance inducer such as DCIA, salicylic acid (SA) or a benzothiadiazole (BTH). In addition, long‐term root pretreatment with DCIA conditioned the hypocotyls for enhanced elicitor responses. These results demonstrate that the above inducers of acquired resistance can affect expression of the cucumber chitinase gene not only as direct inducers. They can also act synergistically with fungal elicitors and, in addition, condition the hypocotyls in a developmental manner for potentiated elicitation.
Salicylic acid has a dual role in the activation of defence‐related genes in parsley
Authors: Thulke Oliver , Conrath Uwe 
Published: March 2003

SummarySystemic acquired resistance is an inducible plant defence state, the activation of which depends mostly on the accumulation of salicylic acid (SA). During the past several years, it has been demonstrated that pretreatment of cultured parsley cells with SA potentiates the elicitation of several defence responses that are local in whole plants, including the accumulation of phenylpropanoid products. Here it is reported that while anionic peroxidase and mannitol dehydrogenase encoding genes are directly responsive to SA, pretreating parsley cells with SA not only enhances elicitation of the phenylpropanoid genes phenylalanine ammonia‐lyase and 4‐coumarate:CoA ligase but also of genes for PR‐10 and a hydroxyproline‐rich glycoprotein. Enhanced induction of these genes was seen at low levels of endogenous free SA. Enhancement of phenylalanine ammonia‐lyase gene activation was proportional to the length of SA pretreatment. Furthermore, the ability of SA analogues to both potentiate elicited and directly induce defence gene activation correlated with their biological activity to promote plant disease resistance. In summary, these results emphasize that SA has at least a dual role in plant defence gene activation.
Psl: a novel Spm‐like transposable element from Petunia hybrida
Authors: Snowden Kimberley C. , Napoli Carolyn A. 
Published: March 2003

SummaryThe identification of a spontaneous mutable Hf1 allele in Petunia hybrida provided an opportunity to isolate and characterize a novel transposable element. This 9.9 kb element has features in common with members of the Spm family, such as homologous terminal inverted repeats and a 3 bp target site direct duplication within the Hf1 gene. The element is named Petunia Spm‐like (Psl). The footprints left by excising elements have been isolated from several germinal revertants and sequence analysis shows similarities to those left by other Spm family members. Southern analysis shows that the transposon is present at low copy number in the genome of different inbred lines and species of Petunia. The germinal excision frequency of Psl was 21–33% in outcross populations. The element appears to be very mobile somatically in the inbred line V26, with 38% of plants from an inbred population showing new Psl‐hybridizing bands by Southern analysis. The high somatic and germinal excision frequency demonstrated by Psl suggests that this element may have utility for gene tagging in petunia.
A novel tomato gene that rapidly responds to wound‐ and pathogen‐related signals
Authors: O'Donnell Philip J. , Truesdale Mark R. , Calvert Caroline M. , Dorans Alison , Roberts Michael R. , Bowles Dianna J. 
Published: March 2003

SummaryThe expression of a novel defence‐related gene from tomato which responds rapidly to wound‐ and pathogen‐related signals has been characterised. The gene, which encodes a protein with homology to glucosyl transferase enzymes, is expressed within 15 min of mechanical damage to tomato leaves, and responds to signals which differ from those on the systemin/jasmonic acid pathway typical of well‐characterised wound‐induced genes of tomato. Furthermore, expression of the gene is also rapidly and specifically induced during a resistance response elicited by the application of Avr9 avirulence peptide to tomato plants carrying the corresponding Cf9 resistance gene. Whilst expression can also be induced by the application of exogenous salicylic acid and related analogues to tomato plants, several lines of evidence suggest that elevated salicylic acid is not a causal signal in planta during either the wound or pathogen resistance response.
An efficient screening for terminal deletions and translocations of barley chromosomes added to common wheat
Authors: Schubert Ingo , Shi Fang , Fuchs Jörg , Endo Takashi R. 
Published: March 2003

SummaryAs a prerequisite to determine physical gene distances in barley chromosomes by deletion mapping, a reliable, fast and inexpensive approach was developed to detect terminal deletions and translocations in individual barley chromosomes added to the chromosome complement of common wheat. A refined fluorescence in situ hybridization (FISH) technique subsequent to N‐banding made it possible to detect subtelomeric repeat sequences (HvT01) on all 14 chromosome arms of barley. Some chromosome arms could be distinguished individually based on the number of FISH signals or the intensity of terminal FISH signals. This allowed the detection and selection of deletions and translocations of barley chromosomes (exemplified by 7H and 4HL), which occurred in the progeny of the wheat lines containing a pair of individual barley chromosomes (or telosomes) and a single so‐called gametocidal chromosome (2C) of Aegilops cylindrica. This chromosome is known to cause chromosomal breakage in the gametes in which it is absent. Terminal deletions and translocations in barley chromosomes were easily recognized in metaphase and even in interphase nuclei by a decrease in the number of FISH signals specific to the subtelomeric repeat. These aberrations were verified by genomic in situ hybridization. The same approach can be applied to select deletions and translocations of other barley chromosomes in wheat lines that are monosomic for the Ae. cylindrica chromosome 2C.
Differential gene expression in Arabidopsis monitored using cDNA arrays
Authors: Desprez Thierry , Amselem Joëlle , Caboche Michel , Höfte Herman 
Published: March 2003

SummaryLarge numbers of genes are being discovered on a daily basis for a variety of organisms including Arabidopsis thaliana. To obtain more functional information on these genes, efficient expression monitoring methods need to be developed. In this report we studied the steady‐state mRNA levels of over 800 Arabidopsis genes in parallel using high‐density arrays of partially sequenced cDNA. The technology is simple and robust and reliably permits the detection of down to twofold variation in mRNA levels. The detection limit lies below 0.01% of the total mRNA population. The comparison of the profiles obtained for light‐grown and dark‐grown seedlings revealed significant variations in mRNA levels for about 16% of the cDNA investigated. This technology not only provides new functional information on anonymous genes, and thus may guide reverse‐genetics approaches, but also constitutes a powerful tool for global gene expression studies, with many potential applications in plant biology.