bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organ identity genes and modified patterns of flower development inGerbera hybrida(Asteraceae)
Authors: Yu Deyue , Kotilainen Mika , Pöllänen Eija , Mehto Merja , Elomaa Paula , Helariutta Yrjö , Albert Victor A. , Teeri Teemu H. 
Published: March 2003

Summary We have used

Gerbera hybrida

(the cultivated ornamental, gerbera) to investigate the molecular basis of flower development in Asteraceae, a family of flowering plants that have heteromorphic flowers and specialized floral organs. Flowers of the same genotype may differ in a number of parameters, including sex expression, symmetry, sympetaly and pigmentation. In order to study the role of organ identity determination in these phenomena we isolated and functionally analysed six MADS box genes from gerbera; these were shown by phylogenetic analysis to be orthologous to well characterized regulatory genes described from

Arabidopsis

and

Antirrhinum

. Expression analysis suggests that the two gerbera

agamous

orthologues, the

globosa

orthologue and one of the

deficiens

orthologues may have functional equivalency to their counterparts, participating in the C and B functions, respectively. However, the function of a second

deficiens

orthologue appears unrelated to the B function, and that of a

squamosa

orthologue seems distinct from

squamosa

as well as from the A function. The induction patterns of gerbera MADS box genes conform spatiotemporally to the multi‐flowered, head‐like inflorescence typical of Asteraceae. Furthermore, gerbera plants transgenic for the newly isolated MADS box genes shed light onto the mechanistic basis for some floral characteristics that are typical for Asteraceae. We can conclude, therefore, that the pappus bristles are sepals highly modified for seed dispersal, and that organ abortion in the female marginal flowers is dependent upon organ identity and not organ position when position is homeotically altered.
Dissection of the ozone‐induced calcium signature
Authors: Clayton Helen , Knight Marc R. , Knight Heather , McAinsh Martin R. , Hetherington Alistair M. 
Published: March 2003

Summary The cellular responses of plants to numerous extracellular stimuli are mediated by transient elevations in the concentration of cytosolic free calcium ([Ca2+]cyt). We have addressed the question of how cells can use this apparently ubiquitous system to initiate so many specific and appropriate end responses. We show that the pollutant gas ozone elicits a biphasic Ca2+ response in intact Arabidopsis plants and a subsequent increase in expression of the gene encoding the antioxidant defence enzyme glutathione‐
S
‐transferase (GST). The second of the two [Ca2+]cyt peaks, but not the first, could be eliminated either by pre‐treatment of plants with lanthanum chloride, or by reducing the duration of ozone fumigation. Under these conditions, ozone‐induced
GST
expression was abolished. These data provide a functional dissection of the ozone Ca2+ signalling pathway and indicate that the second ozone‐induced [Ca2+]cyt peak provides the necessary information to direct expression of
GST
.
Rice ENOD40: isolation and expression analysis in rice and transgenic soybean root nodules
Authors: Kouchi Hiroshi , Takane Ken‐ichi , So Rollando B.. , Ladha Jagdish K.. , Reddy Pallavolu M.. 
Published: March 2003

SummaryThe early nodulin ENOD40 has been proposed as playing a pivotal role in the organogenesis of legume root nodules. We have isolated the ENOD40 gene homologues ObENOD40 and OsENOD40 from the wild and cultivated rice genotypes Oryza brachyantha and Oryza sativa, respectively. Rice ENOD40s contain a sequence at the 5′ end (region I) for encoding an oligopeptide that is highly conserved in all legume ENOD40s. Furthermore, at the 3′ end (region II), the nucleotide sequence of rice ENOD40s exhibited a considerable homology to the corresponding region in legume ENOD40s. Among various organs of the rice plant, expression of OsENOD40 was detected only in stems. In situ hybridization studies revealed that, within the stem, transcription of OsENOD40 is confined to parenchyma cells surrounding the protoxylem during the early stages of development of lateral vascular bundles that conjoin an emerging leaf. Expression pattern of OsENOD40 promoter– GUS fusion in nodules developed on transgenic hairy roots of soybean was also found to be restricted to peripheral cells of nodule vascular bundles, thus evidencing that rice ENOD40 promoter activity is essentially the same as that of soybean ENOD40. Taken together, these results strongly suggest that OsENOD40 and legume ENOD40s share common, if not identical, functions in differentiation and/or function of vascular bundles.
The cell cycle dependent phosphorylation of histone H3 is correlated with the condensation of plant mitotic chromosomes
Authors: Houben Andreas , Wako Toshiyuki , Furushima‐Shimogawara Rieko , Presting Gernot , Künzel Gottfried , Schubert Ingo , Fukui Küchi 
Published: March 2003

SummaryMitotically dividing cells of Secale cereale, Hordeum vulgare and Vicia faba were studied by indirect immunofluorescence using an antibody recognizing phosphorylated histone H3. The study revealed the following features: (i) the H3 phosphorylation starts at prophase and ends at telophase in the pericentromeric chromatin, is associated with the condensation of mitotic chromosomes and is independent of the distribution of late replicating heterochromatin. (ii) Compared with other chromosome regions, the pericentromeric chromatin is histone H3 hyperphos‐ phorylated. (iii) The study of a semi‐dicentric chromo‐ some revealed that only at intact centromeres is the chromatin hyperphosphorylated at H3.
Signaling from the embryo conditions Vp1‐mediated repression of α‐amylase genes in the aleurone of developing maize seeds
Authors: Hoecker Ute , Vasil Indra K. , McCarty Donald R. 
Published: March 2003

SummaryThe VP1 transcription factor functions as both a repressor and an activator of gene expression in the developing aleurone. Vp1 activation of the anthocyanin pathway exhibits strict cell autonomy in aleurone. In contrast, Vp1‐mediated repression of hydrolase genes in aleurone cells during seed development is determined by a combination of cell autonomous and cell non‐autonomous signals. To analyze signaling between the embryo and aleurone during seed development, a T‐B3La chromosome translocation was used to create seed that has non‐concordant embryo and endosperm genotypes. We show that de‐repression of an Amy‐GUS reporter gene in developing vp1 mutant aleurone cells strongly depends on the presence of a viviparous embryo. Genetic ablation of the developing embryo in vp1 mutant and Vp1 seeds through the introduction of an early embryo mutation caused a similar enhancement of Amy‐GUS expression in the aleurone, suggesting that the quiescent embryo present in normal seed is a critical source of inhibitory signals. Analysis of an ABA deficient vp1 vp5 double mutant indicates that ABA synthesized in the embyro interacts additively with Vp1 to prevent precocious induction of α‐amylase genes in the aleurone of the developing seed. A lack of ABA synthesis, however, does not account for the strongly synergistic interaction between a viviparous vp1 embryo and mutant aleurone suggesting that a quiescent embyro is a source of other inhibitory signals.
Maize calreticulin localizes preferentially to plasmodesmata in root apex
Authors: Baluška František , Šamaj Jozef , Napier Richard , Volkmann Dieter 
Published: March 2003

SummaryUsing a polyclonal antibody raised against calreticulin purified and sequenced from maize, we performed an immunocytological study to characterize putative domain‐specific subcellular distributions of endoplasmic reticulum (ER)‐resident calreticulin in meristematic cells of maize root tip. At the light microscopy level, calreticulin was immunolocalized preferentially at cellular peripheries, in addition to nuclear envelopes and cytoplasmic structures. Punctate labelling at the longitudinal walls and continuous labelling at the transverse walls was characteristic. Immunogold electron microscopy revealed plasmodesmata as the most prominently labelled cell periphery structure. In order to further probe the ER‐domain‐specific distribution of maize calreticulin at plasmodesmata, root apices were exposed to mannitol‐induced osmotic stress. Plasmolysis was associated with prominent accumulations of calreticulin at callose‐enriched plasmodesmata and pit fields while the contracting protoplasts were depleted of calreticulin. In contrast, other ER‐resident proteins recognized by HDEL peptide and BiP antibodies localized exclusively to contracted protoplasts. This finding reveals that, in plasmolysed cells, calreticulin enriched ER domains at plasmodesmata and pit fields are depleted of other ER‐resident proteins containing the HDEL retention peptide.
Characterization of the unconventional myosin VIII in plant cells and its localization at the post‐cytokinetic cell wall
Authors: Reichelt Stefanie , Knight Alex E. , Hodge Tony P. , Baluska Frantisek , Samaj Jozef , Volkmann Dieter , Kendrick‐Jones John 
Published: March 2003

SummaryMyosins are a large superfamily of motor proteins which, in association with actin, are involved in intra‐ cellular motile processes. In addition to the conventional myosins involved in muscle contractility, there is, in animal cells, a wide range of unconventional myosins implicated in membrane‐associated processes, such as vesicle transport and membrane dynamics. In plant cells, however, very little is known about myosins. We have raised an antibody to the recombinant tail region ofArabidopsis thalianamyosin 1 (a class VIII myosin) and used it in immunofluorescence and EM studies on root cells from cress and maize. The plant myosin VIII is found to be concentrated at newly formed cross walls at the stage in which the phragmoplast cytoskeleton has depolymerized and the new cell plate is beginning to mature. These walls are rich in plasmodesmata and we show that they are the regions where the longitudinal actin cables appear to attach. Myosin VIII appears to be localized in these plasmodesmata and we suggest that this protein is involved in maturation of the cell plate and the re‐establishment of cytoplasmic actin cables at sites of intercellular communication.
Rapid isolation of plant Ty1‐copia group retrotransposon LTR sequences for molecular marker studies
Authors: Pearce Stephen R. , Stuart‐Rogers Caroline , Knox Maggie R. , Kumar Amar , Ellis T. H. Noel , Flavell Andrew J. 
Published: March 2003

SummaryThe terminal sequences of long‐terminal repeat (LTR) retrotransposons are a source of powerful molecular markers for linkage mapping and biodiversity studies. The major factor limiting the widespread application of LTR retrotransposon‐based molecular markers is the availability of new retrotransposon terminal sequences. We describe a PCR‐based method for the rapid isolation of LTR sequences of Ty1‐copia group retrotransposons from the genomic DNA of potentially any higher plant species. To demonstrate the utility of this technique, we have identified a variety of new retrotransposon LTR sequences from pea, broad bean and Norway spruce. Primers specific for three pea LTRs have been used to reveal polymorphisms associated with the correspond‐ ing retrotransposons within the Pisum genus.
Analysis of mRNA stabilities during pollen development and in BY2 cells
Authors: Ylstra Bauke , McCormick Sheila 
Published: March 2003

SummaryRNA stability is important in post‐transcriptional gene expression. However, its role during plant male gametophyte development has not been studied in detail, probably because of technical difficulties and because earlier work suggested that, in general, mRNAs expressed during late pollen development would be stable. We determined mRNA stabilities of 12 pollen‐expressed genes. We measured pollen mRNA decay during in planta development and in vitro maturation after transcriptional inhibition with ActinomycinD (ActD). Because five of these genes were also expressed in somatic cells we also measured RNA decay in BY2 cells after transcriptional inhibition with ActD. Ten of the mRNAs were highly stable during pollen development (t1/2 > 30 h), including all seven pollen‐specific mRNAs. However, two mRNAs showed a logarithmic decrease as pollen development proceeded, both in planta and in vitro. In fact, for one of these two, GUT8‐2b, the mRNA level decreased significantly within 3 h. Our results show that many pollen‐expressed mRNAs are indeed long‐lived but that at least some mRNAs undergo decay during pollen maturation. Thus, there is no overall cytoplasmic condition in pollen that stabilizes mRNAs and specific mRNA turnover mechanisms must exist. We detected reciprocal mRNA stabilities with two genes that are expressed in both BY2 cells and pollen. GUT15 mRNA, known to be unstable (t1/2 < 3 h) in BY2 cells, was highly stable in pollen. In contrast, GRP2 mRNA decayed in pollen but was highly stable in BY2 cells. Therefore, we conclude that mRNA stability can be tissue‐specific.
A rapid method for detection of plant gene transcripts from single epidermal, mesophyll and companion cells of intact leaves
Authors: Brandt Stephan , Kehr Julia , Walz Christina , Imlau Astrid , Willmitzer Lothar , Fisahn Joachim 
Published: March 2003

SummaryA protocol for the detection of gene transcripts from single plant cells in living, undamaged plant tissue is described. Samples of leaf epidermal, mesophyll and companion cells were extracted by using glass microcapillaries and directly subjected to RT–PCR without any purification steps nor time consuming construction of cDNA libraries. The procedure is not restricted to surface cells or outer cell layers. Even cells from the central region of leaves could be harvested. For identification, companion cells were labelled by expression of the green fluorescent protein under control of a companion cell specific promoter. The described method is applicable to a wide range of plants and genes with different expression levels.
A heat shock transcription factor in pea is differentially controlled by heat and virus replication
Authors: Aranda Miguel A. , Escaler Margarita , Thomas Carole L. , Maule Andrew J. 
Published: March 2003

SummarySince some heat‐inducible genes [heat shock (hs) genes] can be induced by virus infection in pea [e.g. Hsp70;Aranda et al. 1996, Proc. Natl Acad. Sci. USA 93, 15289–15293], we have investigated the effect that heat and virus replication may have on the expression of a heat‐shock transcription factor gene (Hsf). We have characterized what appears to be the only member of the Hsf family in pea, PsHsfA. Similar to Hsp70, PsHsfA is heat‐inducible in vegetative and embryonic tissues, which is concordant with the presence of heat shock elements (HSEs) and stress responsive elements (STREs) on its promoter sequence. The expression of PsHsfA during virus replication was studied in pea cotyledons and leaves, and compared to that of Hsp70. In situ hybridization experiments showed that whereas Hsp70 is induced, there is no detectable increased accumulation of PsHsfA RNA associated with the replication of pea seed‐borne mosaic potyvirus (PSbMV). These experiments indicate that there is a selective control of virus‐induced hs gene expression, and suggest that different regulatory pathways control hs gene expression during heat shock and virus replication.
Light perception and the role of the xanthophyll cycle in blue‐light‐dependent chloroplast movements in Lemna trisulca L.
Authors: Tlałka Monika , Runquist Mårten , Fricker Mark 
Published: March 2003

SummaryIn most higher plants, chloroplasts move towards the periclinal cell walls in weak blue light (WBL) to increase light harvesting for photosynthesis, and towards the anticlinal walls as an escape reaction, thus avoiding photo‐damage in strong blue light (SBL). The photo‐ receptor(s) triggering these responses have not yet been identified. In this study, the role of zeaxanthin as a blue‐light photoreceptor in chloroplast movements was investigated. Time‐lapse 3D confocal imaging in Lemna trisulca showed that individual chloroplasts responded to local illumination when one half of the cell was treated with light of different intensity or spectral quality to that received by the other half, or was maintained in darkness. Thus the complete signal perception, transduction and effector system has a high degree of spatial resolution and is consistent with localization of part of the transduction chain in the chloroplasts. Turnover of xanthophylls was determined using HPLC, and a parallel increase was observed between zeaxanthin and chloroplast movements in SBL. Ascorbate stimulated both a transient increase in zeaxanthin levels and chloroplast movement to profile in physiological darkness. Conversely, dithiothreitol blocked zeaxanthin production and responses to SBL and, to a lesser extent, WBL. Norflurazon preferentially inhibited SBL‐dependent chloroplast movements. Increases in zeaxanthin were also observed in strong red light (SRL) when no directional chloroplast movements occurred. Thus it appears that a combination of zeaxanthin and blue light is required to trigger responses. Blue light can cause cis–trans isomerization of xanthophylls, thus photo‐isomerization may be a critical link in the signal transduction pathway.
Spatio‐temporal analysis of mitotic activity with a labile cyclin–GUS fusion protein
Authors: Colón‐Carmona Adán , You Ratha , Haimovitch‐Gal Tal , Doerner Peter 
Published: March 2003

SummaryPlant growth responds rapidly to developmental and environmental signals, but the underlying changes in cell division activity are poorly understood. A labile cyclin‐GUS reporter was developed to facilitate the spatio‐temporal analysis of cell division patterns. The chimeric reporter protein is turned over every cell cycle and hence its histochemical activity accurately reports individual mitotic cells. Using Arabidopsis plants transformed with cyclin‐GUS, we visualized patterns of mitotic activity in wounded leaves which suggest a role for cell division in structural reinforcement.
Characterization of salicylic acid‐responsive, Arabidopsis Dof domain proteins: overexpression of OBP3 leads to growth defects
Authors: Kang Hong‐Gu , Singh Karam B. 
Published: March 2003

SummaryDof proteins are unique to plants and contain a single zinc finger DNA‐binding domain called the Dof domain. OBP1, an Arabidopsis Dof protein, was previously isolated through an interaction with OBF4, an ocs element‐binding protein. Two additional Dof proteins, called OBP2 and OBP3, were isolated through homologous screening. All three OBP proteins contain transcriptional activation domains in their C‐terminal region. While no significant differences were found between the OBP proteins in terms of their DNA and protein‐binding properties, tissue‐specific RNA expression patterns were found. The RNA expression levels of all three OBP proteins increased following treatment with auxin, salicylic acid (SA) or cycloheximide, although the level of induction varied among the different proteins and in the tissues tested. These results suggest that even though they have similar DNA binding and protein–protein interaction properties, the different OBP proteins are likely to have distinct functions in specific parts of the plant. There is a good correlation between the expression of the OBP proteins and the ocs element, a stress‐response element which is also induced by auxin, SA and cycloheximide. To begin to analyze the function of the OBP proteins, transgenic lines overexpressing OBP3 were generated. These plants showed a severe growth defect with altered root development and yellowish leaves. The severity of the growth defects correlated with OBP3 expression levels and in some cases led to death, suggesting that some Dof proteins play important roles in plant growth and development.
A bifunctional epimerase‐reductase acts downstream of the MUR1 gene product and completes the de novo synthesis of GDP‐L‐fucose in Arabidopsis
Authors: Bonin Christopher P. , Reiter Wolf‐Dieter 
Published: March 2003

SummaryL‐Fucose is a monosaccharide found as a component of glycoproteins and cell wall polysaccharides in higher plants. The MUR1 gene of Arabidopsis thaliana encodes a GDP‐
d‐mannose 4,6‐dehydratase catalyzing the first step in the de novo synthesis of GDP‐
l‐fucose from GDP‐
d‐mannose (
Bonin et al. 1997
, Proc. Natl Acad. Sci. USA, 94, 2085–2090). Plant genes encoding the subsequent steps in
l‐fucose synthesis (3,5‐epimerization and 4‐reduction) have not been described previously. Based on sequence similarities to a bacterial gene involved in capsule synthesis we have cloned a gene from Arabidopsis, now designated GER1, which encodes a bifunctional 3,5‐epimerase‐4‐reductase in
l‐fucose synthesis. The combined action of the MUR1 and GER1 gene products converts GDP‐
d‐mannose to GDP‐
l‐fucose in vitro demonstrating that this entire nucleotide–sugar interconversion pathway could be reconstituted using plant genes expressed in Escherichia coli. In vitro assays indicated that the GER1 protein does not act as a GDP‐
d‐mannose 3,5‐epimerase, an enzymatic activity involved in the de novo synthesis of GDP‐
l‐galactose and
l‐ascorbic acid. Similarly,
l‐ascorbate levels in GER1 antisense plants were unchanged indicating that GDP‐
d‐mannose 3,5‐epimerase is encoded by a separate gene.
In vivo analysis of plant promoters and transcription factors by agroinfiltration of tobacco leaves
Authors: Yang Yinong , Li Rugang , Qi Min 
Published: March 2003

SummaryA convenient, Agrobacterium‐mediated transient expression assay has been evaluated for rapid analysis of plant promoters and transcription factors in vivo. By simple infiltration of Agrobacterium cells carrying appropriate plasmid constructs into tobacco leaves in planta, reproducible expression assays could be conducted in as little as 2–3 days without using expensive equipment (e.g. biolistic gun or electroporation apparatus) or complicated procedures (e.g. preparation of protoplasts). Biotic and abiotic treatments could be applied to the intact plant to examine their influence on promoter activity and gene expression. Using this method, we have tested the stress‐responsive as‐1 and heat shock elements, yeast GAL4 transactivation system, two promoters of pathogenesis‐related (PR) genes as well as a heat shock promoter. Through deletion analyses of tobacco PR1a promoter and a novel myb1 promoter, we have also successfully identified the cis‐regulatory regions in these promoters that are responsive to salicylic acid treatment or tobacco mosaic virus infection. Together, our results demonstrate that Agrobacterium‐mediated transient expression is a simple and efficient method for in vivo assays of plant promoters and transcription factors.
Efficient insertion mutagenesis of Arabidopsis by tissue culture‐induced activation of the tobacco retrotransposon Tto1
Authors: Okamoto Hiroyuki , Hirochika Hirohiko 
Published: March 2003

SummaryThe tobacco retrotransposon Tto1 is one of a few active retrotransposons in plants. Its transposition is activated by tissue culture and is primarily regulated at the transcriptional level. Here we demonstrate that Tto1 introduced in Arabidopsis is also activated by tissue culture. Transcription of Tto1 was induced by tissue culture and driven by its LTR promoter. Transposed copies of Tto1 were observed in almost all of the plants regenerated from the explants cultured for only 1 week. A total of 255 independent regenerated lines have been produced, and the average copy number of transposed Tto1 in these lines is estimated to be 3.2. Sequences flanking Tto1 were amplified by thermal asymmetric interlaced (TAIL)‐PCR. Of 165 independent amplified products, 123 showed significant homology to known genes or hypothetical protein genes. The insertion sites of Tto1 are spread over all chromosomes and the target site sequence shows moderate consensus. Taken together, these results indicate that Tto1 can be used as a tool for efficient insertion mutagenesis of Arabidopsis which is especially suitable as a reverse genetics system.