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At least 793 records · Page 44Linked to original sources
PubMed1992

The function of vacuolar beta-1,3-glucanase investigated by antisense transformation. Susceptibility of transgenic Nicotiana sylvestris plants to Cercospora nicotianae infection.

Vacuolar class I beta-1,3-glucanases (EC 3.2.1.39) are believed to be important in the induced defense reaction of plants to fungal infection. We used antisense transformation to test this hypothesis and to identify other possible physiological functions of this enzyme. Nicotiana sylvestris plants were transformed with antisense constructions containing the region from position 27 to 608 of the coding sequence of the basic, vacuolar beta-1,3-glucanase gene GLA of tobacco regulated by cauliflower mosaic virus 35S RNA expression signals. Plants homozygous for this transgene showed a marked, ca. 20-fold reduction in the constitutive expression of class I beta-1,3-glucanase antigen in their leaves. RNA blot analysis indicated that the antisense plants expressed low levels of the sense transcript of the host beta-1,3-glucanase gene and the antisense transcript of the transgene. Immune blot analysis of plant extracts indicated that only expression of the N. sylvestris homologue of class I tobacco beta-1,3-glucanase and not the acidic, class II isoforms of the enzyme was blocked in the antisense plants. Class I isoforms of beta-1,3-glucanase and chitinase were coordinately induced in leaves of untransformed and empty-vector-transformed N. sylvestris plants treated with ethylene or infected with the fungal leaf pathogen Cercospora nicotianae. In antisense plants, chitinase but not beta-1,3-glucanase was induced under these conditions indicating that antisense transformation effectively blocks constitutive as well as induced expression of class I beta-1,3-glucanase. Under greenhouse conditions, antisense plants developed normally and were fertile. The plants did not exhibit increased susceptibility to C. nicotianae infection. These results suggest that expression of the beta-1,3-glucanase isoform blocked by antisense transformation is not necessary for 'housekeeping' functions of N. sylvestris nor defense against the fungal pathogen tested.

Blotting, Northern↗
PubMed1995

A two-element Enhancer-Inhibitor transposon system in Arabidopsis thaliana.

The Enhancer-Inhibitor (En-I), also known as Suppressor-mutator (Spm-dSpm), transposable element system of maize was modified and introduced into Arabidopsis by Agrobacterium tumefaciens transformation. A stable En/Spm transposase source under control of the CaMV 35S promoter mediated frequent transposition of I/dSpm elements. Transposition occurred continuously throughout plant development over at least seven consecutive plant generations after transformation. New insertions were found at both linked and unlinked positions relative to a transposon donor site. The independent transposition frequency was defined as a transposition parameter, which quantified the rate of unique insertion events and ranged from 7.8% to 29.2% in different populations. An increase as well as a decrease in I/dSpm element copy number was seen at the individual plant level, but not at the population level after several plant generations. The continuous, frequent transposition observed for this transposon system makes it an attractive tool for use in gene tagging in Arabidopsis.

Arabidopsis↗
PubMed2001

Developmentally regulated expression of a cyclic nucleotide-gated ion channel from Arabidopsis indicates its involvement in programmed cell death.

Cyclic nucleotide-gated ion channels have been identified in animals and plants. However, the physiological role of these ion channels in plant cells and in non-receptor cells of animals is still unknown. Here, we focused on one member of the large gene family of cyclic nucleotide-gated ion channels from Arabidopsis thaliana (L.) Heynh., AtCNGC2. The analysis of the transcriptional regulation revealed that expression of AtCNGC2 is low in etiolated seedlings but increases substantially during de etiolation. The use of promoter::GUS plants revealed that expression of AtCNGC2 in seedlings is highest in cotyledons after release of the developmental arrest by light. Expression of AtCNGC2 was also observed in later stages of plant development. Investigations using the promoter::GUS plants demonstrated that AtCNGC2 is expressed in flowers during organ senescence and in the dehiscence zone of siliques. Furthermore, expression of AtCNGC2 was transiently induced during leaf and cell culture senescence. These results indicate a potential function for AtCNGC2 in the initiation of developmentally regulated cell death programs.

Animals↗
PubMed1989

Genetic mosaics and cell lineage analysis in plants.

The use of genetic mosaics for cell lineage analysis has revealed several important features of plant development. All multicellular organs in higher plants are polyclonal in origin. Although primordial cell lineages have fairly regular fates, the fate of any given cell within these lineages cannot be accurately predicted. Cell fate appears to be determined by the final location of a cell rather than by its history.

Chimera↗
PubMed1998

Protein transport within the plant cell endomembrane system: an update.

The secretory pathway plays a central role in plant development and morphogenesis. Storage protein deposition, plant cell division and the expansion of the plasma membrane and extracellular matrix all require the synthesis and trafficking of membranes, proteins and polysaccharides through this network of organelles. Increasing evidence demonstrates that the plant secretory pathway is more complex than previously appreciated and that its formation and maintenance are guided/regulated by many different mechanisms.

Biological Transport↗
PubMed2001

Multiple pathways for Cre/lox-mediated recombination in plastids.

Plastid transformation technology involves the insertion by homologous recombination and subsequent amplification of plastid transgenes to approximately 10 000 genome copies per leaf cell. Selection of transformed genomes is achieved using a selectable antibiotic resistance marker that has no subsequent role in the transformed line. We report here a feasibility study in the model plant tobacco, to test the heterologous Cre/lox recombination system for antibiotic marker gene removal from plastids. To study its efficiency, a green fluorescent protein reporter gene activation assay was utilized that allowed visual observation of marker excision after delivery of Cre to plastids. Using a combination of in vivo fluorescence activation and molecular assays, we show that transgene excision occurs completely from all plastid genomes early in plant development. Selectable marker-free transplastomic plants are obtained in the first seed generation, indicating a potential application of the Cre/lox system in plastid transformation technology. In addition to the predicted transgene excision event, two alternative pathways of Cre-mediated recombination were also observed. In one alternative pathway, the presence of Cre in plastids stimulated homologous recombination between a 117 bp transgene expression element and its cognate sequence in the plastid genome. The other alternative pathway uncovered a plastid genome 'hot spot' of recombination composed of multiple direct repeats of a 5 bp sequence motif, which recombined with lox independent of sequence homology. Both recombination pathways result in plastid genome deletions. However, the resultant plastid mutations are silent, and their study provides the first insights into tRNA accumulation and trans-splicing events in higher plant plastids.

Arabidopsis↗
PubMed1998

Is blue light good or bad for plants?

Blue photons are energetically expensive so the most energy-efficient lamps contain the least blue light. Blue photons are not used efficiently in photosynthesis, but blue light has dramatic effects on plant development. We studied the growth and development of soybean, wheat, and lettuce plants under high-pressure sodium and metal halide lamps with yellow filters creating five fractions of blue light (0.5%, 3.5%, 6%, 1 8%, and 26% blue) at 500 micromoles m-2 s-1 and (< 0.1%, 1.7%, 6%, 12%, and 26%) at 200 mol m-2 s-1. The response was species dependent. Lettuce was highly sensitive to blue light fraction and had an optimum dry weight and leaf area at about 6% blue, but results were complicated by sensitivity to lamp type. Wheat and soybean were less sensitive to blue light, but dry mass and leaf area decreased steadily with increasing blue light. Blue light fraction significantly affected specific leaf area (SLA, m2 kg-1) and chlorophyll in lettuce, but had no significant effect on wheat and soybeans. The data suggest that lettuce benefits from some added blue light, but soybean and wheat may not.

Biomass↗
PubMed2004

Cloning of LjCYC1 gene and nuclear localization of LjCYC1 protein in Lotus japonicus.

The LjCYC1 (Lotus japonicus Cycloidea-like 1) gene, a homolog of CYC (Cycloidea) belonging to the TCP [TB1(teosinte branched 1), CYC, PCFs (PCF1 and PCF2)] gene family and encoding a predicted transcription factor and being proposed controlling different aspects of plant development, was isolated from the papilionaceous plant Lotus japonicus by screening the genomic DNA library, in order to test the functional conservation and divarication of CYC-like genes in legume. Sequence analyses indicate that LjCYC1 gene contains two exons and one intron and encodes a 370-AA peptide LjCYC1. The putative protein, LjCYC1, contains a TCP domain and an R domain, being a member of the CYC/TB1 subfamily of TCP family, and has 39.0% identity with and 42.6% similarity to CYC. LjCYC1-cDNA was cloned through RT-PCR. Different regions of the LjCYC1-cDNA were fused with the report gene GUS and then the fused constructs were transiently expressed in the onion epidermal cells through particle bombardment. Results of GUS and DAPI staining showed that the chimeric proteins with TCP domain were localized within the nucleus, confirming that LjCYC1 may act as a transcription factor. But the TCP domain itself could not confer the nuclear localization because the chimeric proteins with TCP domain alone were dispersed all over the transformed cells.

Amino Acid Sequence↗
PubMed1998

Oligosaccharide signaling of plant cells.

A variety of oligosaccharide signals have been identified that function in the regulation of plant development, defense, and other interactions of plants with the environment. Some of these oligosaccharides are produced by various pathogens or symbionts, whereas others are synthesized by the plant itself. This mini-review summarizes our present state of information on these oligosaccharide signals and provides an overview of approaches being used to identify receptors for these signals and gain an understanding of the mechanism(s) by which these signals activate downstream events. Possible biotechnological applications of future work in this field are also considered.

Carbohydrate Sequence↗
PubMed2005

RNA interference identifies a calcium-dependent protein kinase involved in Medicago truncatula root development.

Changes in cellular or subcellular Ca2+ concentrations play essential roles in plant development and in the responses of plants to their environment. However, the mechanisms through which Ca2+ acts, the downstream signaling components, as well as the relationships among the various Ca2+-dependent processes remain largely unknown. Using an RNA interference-based screen for gene function in Medicago truncatula, we identified a gene that is involved in root development. Silencing Ca2+-dependent protein kinase1 (CDPK1), which is predicted to encode a Ca2+-dependent protein kinase, resulted in significantly reduced root hair and root cell lengths. Inactivation of CDPK1 is also associated with significant diminution of both rhizobial and mycorrhizal symbiotic colonization. Additionally, microarray analysis revealed that silencing CDPK1 alters cell wall and defense-related gene expression. We propose that M. truncatula CDPK1 is a key component of one or more signaling pathways that directly or indirectly modulates cell expansion or cell wall synthesis, possibly altering defense gene expression and symbiotic interactions.

Arabidopsis Proteins↗
PubMed2005

A possible role for NDPK2 in the regulation of auxin-mediated responses for plant growth and development.

Auxin plays many crucial roles in the course of plant growth and development, such as hook opening, leaf expansion and inhibition of mesocotyl elongation. Although its mechanism of action has not been clarified at the molecular level, recent studies have indicated that auxin triggers the induction of a number of genes known as primary auxin-responsive genes. Hence, the identification of the regulatory components in auxin-mediated cellular responses would help to elucidate the mechanism of the action of this hormone in plant growth and development. NDPK2 encodes a nucleoside diphosphate kinase 2 (NDPK2) in Arabidopsis. We aim to elucidate the possible role of NDPK2 in auxin-related cellular processes, in view of the finding that a ndpk2 mutant displays developmental defects associated with auxin. Interestingly, the ndpk2 mutant exhibits defects in cotyledon development and increased sensitivity to an inhibitor of polar auxin transport (naphthylphthalamic acid; NPA). Consistent with this phenotype, the transcript levels of specific auxin-responsive genes were reduced in the ndpk2 mutant plants treated with auxin. The amount of auxin transported from the shoot apex to the shoot/root transition zone of ndpk2 mutant plants was increased, compared with that in the wild-type plants. These results collectively suggest that NDPK2 appears to participate in auxin-regulated processes, partly through the modulation of auxin transport.

Gene Expression↗
PubMed2005

The control of leaf development.

The formation of a leaf is a basic aspect of plant development. This review provides an overview of our present understanding of the process from initiation to the final form of the leaf. Molecular genetic and cell biology approaches have yielded significant advances in this area, adding not only to our knowledge of leaf development but also to fundamental principles in plant biology. These principles will be highlighted, as well as areas where our understanding is still incomplete, in particular the problem of coordinating the multifaceted steps involved in the generation of the leaf structure.

Cell Differentiation↗
PubMed2005

Quantitative modeling of Arabidopsis development.

We present an empirical model of Arabidopsis (Arabidopsis thaliana), intended as a framework for quantitative understanding of plant development. The model simulates and realistically visualizes development of aerial parts of the plant from seedling to maturity. It integrates thousands of measurements, taken from several plants at frequent time intervals. These data are used to infer growth curves, allometric relations, and progression of shapes over time, which are incorporated into the final three-dimensional model. Through the process of model construction, we identify the key attributes required to characterize the development of Arabidopsis plant form over time. The model provides a basis for integrating experimental data and constructing mechanistic models.

Arabidopsis↗
PubMed2005

Is a physiological perspective relevant in a 'genocentric' age?

Currently, the major thrust of plant physiology research is to identify and understand the regulation of genes that might be relevant in plant development and growth. The dominance of a genocentric view of plant behaviour has, unfortunately, resulted in the development of major disconnects in the classical view of plant physiology as a partnership between fundamental and practical research contributing to improved plant production. One disconnect is that much of the genocentric research appears to be organized and executed without regard to the practical needs of enhancing plant performance under applied conditions. Although practical benefits from genocentric research are often claimed, basic assumptions guiding much research and the experimental protocols used are commonly not relevant for real-world plant production. A second disconnect is a failure fully to appreciate the lessons learned in 40 years of classical plant physiology research concerning the role of physiological processes in altering whole plant performance. Regulation of plant systems has proved to be complex and redundant. Alteration of a single physiological process is compensated or dampened so that commonly very little change in plant growth and yield results from modification of a single physiological process. Based on a few successful projects employing classical plant physiology to achieve crop yield increase, key characteristics for research projects that truly seek to increase plant performance in production systems are identified. Basically, the partnership between the fundamental and practical research long espoused for plant physiology needs to be re-established in an intimate and meaningful way.

Crops, Agricultural↗
PubMed2002

Analysis of the NRT2 nitrate transporter family in Arabidopsis. Structure and gene expression.

Nitrate is an essential element for plant growth, both as a primary nutrient in the nitrogen assimilation pathway and as an important signal for plant development. The uptake of nitrate from the soil and its translocation throughout the plant has been the subject of intensive physiological and molecular studies. Using a reverse genetic approach, the AtNRT2.1 gene has been shown to be involved in the inducible component of the high-affinity nitrate transport system in Arabidopsis. The Arabidopsis Genome Initiative has released nearly the whole genome sequence of Arabidopsis, allowing the identification of a small NRT2 multigene family in this species. Thus, we investigated the phylogenetic relationship between NRT2 proteins belonging to several kingdoms and compared the structure of the different members of the Arabidopsis family. We analyzed, by semiquantitative reverse transcriptase-polymerase chain reaction, the expression pattern of each gene depending on plant organ and development or nutritional status, and compared the relative level of each gene by real-time polymerase chain reaction. We also evaluated the significance of each paralog on the basis of the relative levels of gene expression. The results are discussed in relation with distinct roles for the individual members of the AtNRT2 family.

Anion Transport Proteins↗
PubMed2006

Gamma-tubulin is essential for microtubule organization and development in Arabidopsis.

The process of microtubule nucleation in plant cells is still a major question in plant cell biology. gamma-Tubulin is known as one of the key molecular players for microtubule nucleation in animal and fungal cells. Here, we provide genetic evidence that in Arabidopsis thaliana, gamma-tubulin is required for the formation of spindle, phragmoplast, and cortical microtubule arrays. We used a reverse genetics approach to investigate the role of the two Arabidopsis gamma-tubulin genes in plant development and in the formation of microtubule arrays. Isolation of mutants in each gene and analysis of two combinations of gamma-tubulin double mutants showed that the two genes have redundant functions. The first combination is lethal at the gametophytic stage. Disruption of both gamma-tubulin genes causes aberrant spindle and phragmoplast structures and alters nuclear division in gametophytes. The second combination of gamma-tubulin alleles affects late seedling development, ultimately leading to lethality 3 weeks after germination. This partially viable mutant combination enabled us to follow dynamically the effects of gamma-tubulin depletion on microtubule arrays in dividing cells using a green fluorescent protein marker. These results establish the central role of gamma-tubulin in the formation and organization of microtubule arrays in Arabidopsis.

Arabidopsis↗
PubMed2000

The evolution of nodulation.

In this review we will first describe the different steps leading to nodule formation, and these will be compared with processes of non-symbiotic plant development and growth. In general, aspects of both actinorhizal as well as rhizobial symbiosis are described, but in several cases, the emphasis will be on the Rhizobium-legume symbiosis because more knowledge of this system is available. Subsequently, the phylogeny of nodulating plants is described and a comparison is made between several aspects of legume and actinorhizal nodulation. At the end of this paper the relationship between nodule symbiosis and endomycorrhizal symbiosis is described, and it is discussed to what extent the development of root nodules involves unique properties, or whether processes and genes have been recruited from common plant development and the endomycorrhizal symbiosis.

Actinomycetales↗