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At least 415 records · Page 23Linked to original sources
PubMed2001

[Growth and development of plants in a row of generations under the conditions of space flight (experiment Greenhouse-5)].

Results of the experiment aimed at harvesting a second space generation of wheat var. Apogee in Mir greenhouse Svet (experiment GREENHOUSE-5) are presented. In space flight, germination rate of space seeds from the first crop made up 89% against 100% of the ground seeds. The full biological ripeness was observed in 20 plants grown from the ground seeds and one plant grown from the space seeds following 80- to 90-d vegetation. The plant of the second space generation was morphologically different neither from the species in the first space crop nor from the ground controls. To study the biological characteristics of Apogee seeds gathered in the first and second crops in spaceflight experiment GREENHOUSE-5, the seeds were planted on their return to the laboratory. Morphometric analysis showed that they were essentially similar to the controls. Hence, the space experiments in Mir greenhouse Svet performed during 1998-1999 gave proof that plants cultivated in microgravity can pass the ontogenetic cycle more than once. However, initial results of the investigations into growth and development of plants through several generations are still in-sufficient to speak of possible delayed effects of the spaceflight factors (microgravity, multicomponent radiation, harmful trace contaminants etc.).

Aerospace Medicine↗
PubMed2005

An indole-3-acetic acid carboxyl methyltransferase regulates Arabidopsis leaf development.

Auxin is central to many aspects of plant development; accordingly, plants have evolved several mechanisms to regulate auxin levels, including de novo auxin biosynthesis, degradation, and conjugation to sugars and amino acids. Here, we report the characterization of an Arabidopsis thaliana mutant, IAA carboxyl methyltransferase1-dominant (iamt1-D), which displayed dramatic hyponastic leaf phenotypes caused by increased expression levels of the IAMT1 gene. IAMT1 encodes an indole-3-acetic acid (IAA) carboxyl methyltransferase that converts IAA to methyl-IAA ester (MeIAA) in vitro, suggesting that methylation of IAA plays an important role in regulating plant development and auxin homeostasis. Whereas both exogenous IAA and MeIAA inhibited primary root and hypocotyl elongation, MeIAA was much more potent than IAA in a hypocotyl elongation assay, indicating that IAA activities could be effectively regulated by methylation. IAMT1 was spatially and temporally regulated during the development of both rosette and cauline leaves. Changing expression patterns and/or levels of IAMT1 often led to dramatic leaf curvature phenotypes. In iamt1-D, the decreased expression levels of TCP genes, which are known to regulate leaf curvature, may partially account for the curly leaf phenotype. The identification of IAMT1 and the elucidation of its role in Arabidopsis leaf development have broad implications for auxin-regulated developmental process.

Arabidopsis↗
PubMed2003

Roles of OsCKI1, a rice casein kinase I, in root development and plant hormone sensitivity.

Casein kinases are critical in cell division and differentiation across species. A rice cDNA fragment encoding a putative casein kinase I (CKI) was identified via cDNA macroarray under brassinosteroid (BR) treatment, and a 1939-bp full-length cDNA, OsCKI1, was isolated and found to encode a putative 463-aa protein. RT-PCR and Northern blot analysis indicated that OsCKI1 was constitutively expressed in various rice tissues and upregulated by treatments with BR and abscisic acid (ABA). Enzymatic assay of recombinant OsCKI1 proteins expressed in Escherichia coli showed that the protein was capable of phosphorylating casein. The physiological roles of OsCKI1 were studied through antisense transgenic approaches, and homozygous transgenic plants showed abnormal root development, including fewer lateral and adventitious roots, and shortened primary roots as a result of reduced cell elongation. Treatment of wild-type plants with CKI-7, a specific inhibitor of CKI, also confirmed these functions of OsCKI1. Interestingly, in transgenic and CKI-7-treated plants, exogenously supplied IAA could restore normal root development, and measurement of free IAA content in CKI-deficient primary and adventitious roots revealed altered auxin content, indicating that OsCKI1 is involved in auxin metabolism or that it may affect auxin levels. Transgenic plants were less sensitive than control plants to ABA or BR treatment during germination, suggesting that OsCKI1 may be involved in various hormone-signaling pathways. OsCKI1-GFP fusion studies revealed the localization of OsCKI1 to the nucleus, suggesting a possible involvement in regulation of gene expression. In OsCKI1-deficient plants, differential gene expression was investigated using cDNA chip technology, and results indicated that genes related to signal transduction and hormone metabolism were indeed with altered expression.

Amino Acid Sequence↗
PubMed1999

The maize rough sheath2 gene and leaf development programs in monocot and dicot plants.

Leaves of higher plants develop in a sequential manner from the shoot apical meristem. Previously it was determined that perturbed leaf development in maize rough sheath2 (rs2) mutant plants results from ectopic expression of knotted1-like (knox) homeobox genes. Here, the rs2 gene sequence was found to be similar to the Antirrhinum PHANTASTICA (PHAN) gene sequence, which encodes a Myb-like transcription factor. RS2 and PHAN are both required to prevent the accumulation of knox gene products in maize and Antirrhinum leaves, respectively. However, rs2 and phan mutant phenotypes differ, highlighting fundamental differences in monocot and dicot leaf development programs.

Amino Acid Sequence↗
PubMed2006

Repression of the LEAFY COTYLEDON 1/B3 regulatory network in plant embryo development by VP1/ABSCISIC ACID INSENSITIVE 3-LIKE B3 genes.

Plant embryo development is regulated by a network of transcription factors that include LEAFY COTYLEDON 1 (LEC1), LEC1-LIKE (L1L), and B3 domain factors, LEAFY COTYLEDON 2 (LEC2), FUSCA3 (FUS3), and ABSCISIC ACID INSENSITIVE 3 (ABI3) of Arabidopsis (Arabidopsis thaliana). Interactions of these genes result in temporal progression of overlapping B3 gene expression culminating in maturation and desiccation of the seed. Three VP1/ABI3-LIKE (VAL) genes encode B3 proteins that include plant homeodomain-like and CW domains associated with chromatin factors. Whereas val monogenic mutants have phenotypes similar to wild type, val1 val2 double-mutant seedlings form no leaves and develop embryo-like proliferations in root and apical meristem regions. In a val1 background, val2 and val3 condition a dominant variegated leaf phenotype revealing a VAL function in vegetative development. Reminiscent of the pickle (pkl) mutant, inhibition of gibberellin biosynthesis during germination induces embryonic phenotypes in val1 seedlings. Consistent with the embryonic seedling phenotype, LEC1, L1L, ABI3, and FUS3 are up-regulated in val1 val2 seedlings in association with a global shift in gene expression to a profile resembling late-torpedo-stage embryogenesis. Hence, VAL factors function as global repressors of the LEC1/B3 gene system. The consensus binding site of the ABI3/FUS3/LEC2 B3 DNA-binding domain (Sph/RY) is strongly enriched in the promoters and first introns of VAL-repressed genes, including the early acting LEC1 and L1L genes. We suggest that VAL targets Sph/RY-containing genes in the network for chromatin-mediated repression in conjunction with the PKL-related CHD3 chromatin-remodeling factors.

Arabidopsis↗
PubMedDate not supplied

[The effect of soil inoculation with microbial pesticide destructors on plant growth and development].

Soil inoculation with liquid cultures of Bacillus megaterium 501 and Exophiala nigrum A-29 capable of degrading several organophosphorus pesticides accelerated growth and development of experimental plants, formation of their generative organs, and improved their productivity. This was particularly observed under stress plant growth conditions on phytotoxic peach substrates. The microorganisms inoculated can probably degrade phytotoxins present in soils, thereby favoring the plant development.

Bacillus megaterium↗
PubMedDate not supplied

Regulation of rDNA transcription in plastids of higher plants.

Plastid rDNA expression changes with plastid differentiation, plant development and plant growth conditions. Plastid rDNA operons are preceded by different promoter structures that are recognised by different types of RNA polymerase in a species-specific and development-dependent manner. Present knowledge on regulation of rDNA transcription obtained with plant material corresponding to different developmental stages and/or different plant species is summarised. Results indicate the creation of new and unique transcriptional regulatory mechanisms during the evolutionary integration process of the cyanobacterial ancestor into the present-day multi-cellular organism.

Base Sequence↗
PubMed2005

Regulation of meristem activity by chromatin remodelling.

The continuity and plasticity of plant development rely on the regulation of meristem activity in response to endogenous and environmental signals. Many plant development regulators involved in meristem function are transcription factors or signalling molecules. In the past few years, the role of chromatin remodelling in programming, maintaining or resetting specific gene expression profiles in subsequent cell generations has been shown to be crucial in plant development. Here, we summarize plant chromatin-remodelling factors required to regulate shoot apical meristem activity, particularly its maintenance during organogenesis and transitions between distinct developmental phases.

Chromatin↗
PubMed1991

Light-emitting diodes as a radiation source for plants.

Development of a more effective radiation source for use in plant-growing facilities would be of significant benefit for both research and commercial crop production applications. An array of light-emitting diodes (LEDs) that produce red radiation, supplemented with a photosynthetic photon flux (PPF) of 30 micromoles s-1 m-2 in the 400- to 500-nm spectral range from blue fluorescent lamps, was used effectively as a radiation source for growing plants. Growth of lettuce (Lactuca sativa L. Grand Rapids') plants maintained under the LED irradiation system at a total PPF of 325 micromoles s-1 m-2 for 21 days was equivalent to that reported in the literature for plants grown for the same time under cool-white fluorescent and incandescent radiation sources. Characteristics of the plants, such as leaf shape, color, and texture, were not different from those found with plants grown under cool-white fluorescent lamps. Estimations of the electrical energy conversion efficiency of a LED system for plant irradiation suggest that it may be as much as twice that published for fluorescent systems.

Environment, Controlled↗
PubMed2001

[Growth and development of plants in a sequence of generations under the conditions of space flight (experiment Greenhouse-3)].

The purpose was to study characteristic features of growth and development of several plant generations in space flight in experiment GREENHOUSE-3 as a part of the Russian-US space research program MIR/NASA in 1997. The experiment consisted of cultivation of Brassica rapa L. in board greenhouse Svet. Two vegetative cycles were fully completed and the third vegetation was terminated on day 13 on the phase of budding. The total duration of the space experiment was 122 days, i.e. same as in the ground controls. In the experiment with Brassica rapa L. viable seeds produced by the first crop were planted in space flight and yielded next crop. Crops raised from the ground and space seeds were found to differ in height and number of buds. Both parameters were lowered in the plants grown from the space seeds. The prime course for smaller size and reduced organogenic potential of plantTs reproductive system seems to be a less content of nutrients in seeds that had matured in the space flight. Experiment GREENHOUSE-3 demonstrated principle feasibility of plant reproduction in space greenhouse from seeds developed in microgravity.

Brassica rapa↗
PubMed2004

[Quantitative analysis of active substances in St. John's wort (Hypericum perforatum L.) by the high performance liquid chromatography method].

The flavonoids (rutin, quercetin, and isoquercetin) and hypericin are the main active substances of St. John's wort (Hypericum perforatum). They support regeneration of human body cells, provide disinfection, and act as antidepressant, antiviral, and anti-inflammation tools. Such large spectrum of the applicable functions depends on the quantity of each substance. The objective of this paper is to determine the regularities of the quantitative variation of rutin, quercetin, isoquercetin and hypericin in flowers and leaves of St. John's wort in different habitats and different plant development phases. Plant material for the quantitative analysis was collected in 1998-1999. The high performance liquid chromatography (HPLC) was applied for the quantitative analysis of the active substances in St. John's wort. The flavonoids (rutin, quercetin, and isoquercetin) were identified under the UV waves of 254 nm, and hypericin - under the waves of 590 nm. Larger quantities of rutin were found in leaves, while those of quercetin, isoquercetin and hypericin - in flowers of St. John's wort. The highest accumulation of active substances was observed during the development of flowering buds and in flowering time. The quantitative variation of active substances in different habitats allows the selection of the best plant samples for their cultivation and conservation in field collections.

Anthracenes↗
PubMed2000

Characterizing the interaction between fire ants (Hymenoptera: Formicidae) and developing soybean plants.

This research characterizes the interaction between the fire ants Solenopsis invicta Buren and developing soybean plants. Phagostimulant studies showed that fire ant foraging on soybean seeds increased once the seeds imbibed water. During seedling development over a 5-d germination period, fire ant foraging shifted from the stem/cotyledons to the roots, despite continual increases in fresh weights for each region, and the fact that stem/cotyledon tissue contained the majority of food reserves. Carbohydrate analysis showed that although 2-d-old seedlings had higher concentrations of phagostimulant carbohydrates, especially sucrose, than tissues of mature plants, all tissues analyzed had enough of these sugars to induce a phagostimulant response. Fire ant association with seeds/seedlings germinated in soil resulted in reduced seedling vigor, as determined by a doubling of seedling emergence time, a threefold increase in malformed seedlings, and visible damage to cotyledons. Seeds germinated and grown to mature plants in association with fire ants, allocated 43% more assimilate into pods, but produced 28% less root dry matter, 11% less total dry matter, and there was an 81% reduction in the number of root nodules compared with control plants. We propose that reduced root development and inhibitions of nodule formation would be major yield limiting factors under field conditions. This work demonstrates that fire ant damage to soybeans is not limited to seedling establishment and that more research should be directed at the subterranean activities of the fire ant.

Animals↗
PubMed1995

Calcium and the generation of plant form.

The involvement of mechanical signals (tension and compression) in the determination of the form of living organisms has been speculated upon for many years. These mechanical signals (both environmental and those generated within the plant itself) have significant effects on plant development and thus morphology. Plants respond to externally applied mechanical signals (touch and wind) by an immediate elevation of cytosolic calcium concentration ([Ca2+]eyt) in stimulated cells. This response requires the movement of plant tissues to cause tension and compression. Some of the more longer-term responses to mechanical signals, e.g. TCH gene expression and reduction in hypocotyl growth, show a calcium-dependency. It seems likely, therefore, that the effects of mechanical signals on plant development are mediated by the second messenger, calcium. This raises the exciting possibility that this simple ion plays a central role in the determination of plant form itself.

Calcium↗
PubMed2002

Indole-3-acetic acid metabolism in Lemna gibba undergoes dynamic changes in response to growth temperature.

Auxin is the mobile signal controlling the rate of growth and specific aspects of the development of plants. It has been known for over a century that auxins act as the messenger linking plant development to specific environmental changes. An often overlooked aspect of how this is accomplished is the effect of the environment on metabolism of the major plant auxin, indole-3-acetic acid (IAA). We have studied the metabolism of IAA in relation to one environmental variable, growth temperature. The model system used was an inbred line of the aquatic monocot Lemna gibba G-3, 3F7-11 grown at temperatures ranging from 5 degrees C to 35 degrees C. IAA levels, the rate of IAA turnover, and the patterns of label incorporation from IAA precursors were measured using stable isotope-mass spectrometric techniques and were evaluated relative to growth at the experimental temperatures. IAA levels exhibited unusually high variability in plants grown at 15 degrees C and 20 degrees C. Turnover rates were quite rapid throughout the range of experimental temperatures except at 25 degrees C, where IAA turnover was notably slower. These results suggest that a transition occurred over these temperatures for some aspect of IAA metabolism. Analysis of [(15)N]anthranilate and [(2)H(5)]tryptophan (Trp) incorporation into IAA showed that Trp-dependent biosynthesis predominated at 15 degrees C; however, Trp-independent biosynthesis of IAA was the major route to IAA at 30 degrees C. The effects of growth temperature on auxin levels have been reported previously, but no prior studies correlated these effects with which pathway becomes the primary one for IAA production.

Carbon Radioisotopes↗
PubMed2005

Viral-like symptoms induced by the ectopic expression of the p23 gene of Citrus tristeza virus are citrus specific and do not correlate with the pathogenicity of the virus strain.

Ectopic expression of the p23 gene from a severe (T36) strain of Citrus tristeza virus (CTV) induces viral-like symptoms in Mexican lime. Here, we report that expressing the same gene from a mild strain induced similar symptoms that correlated with accumulation of p23 protein irrespective of the source strain. CTV inoculation of transgenic limes showing CTV-like leaf symptoms and high p23 accumulation did not modify symptoms initially, with the virus titer being as in inoculated nontransgenic controls; however, at later stages, symptoms became attenuated. Transformation with p23-T36 of CTV-susceptible sweet and sour orange and CTV-resistant trifoliate orange also led to CTV-like leaf symptoms that did not develop when plants were transformed with a truncated p23 version. In transgenic citrus species and relatives other than Mexican lime, p23 was barely detectable, although symptom intensity correlated with levels of p23 transcripts. The lower accumulation of p23 in sweet and sour orange compared with Mexican lime also was observed in nontransgenic plants inoculated with CTV, suggesting that minimal p23 levels cause deleterious effects in the first two species. Conversely, transgenic expression of p23 in CTV nonhost Nicotiana spp. led to accumulation of p23 without phenotypic aberrations, indicating that p23 interferes with plant development only in citrus species and relatives.

Amino Acid Sequence↗
PubMedDate not supplied

[Differences in growth and ontogenetic development of plants grown in the Earth gravitational field in the natural and inverse orientation].

Wheat plants Triticum aestivum L., Apogee cultivar, were grown in the natural and inverse orientation of the Earth gravitational field. Special vegetation containers with double bottom were used for the cultivation. The upper bottom made of porous titanium served as a hydrophilic porous membrane stabilizing aquatic potential in the root-inhabited zone at a given level. Normal plants yielding viable seeds were obtained for both natural and inverse orientation. In our experiments, the inverse orientation induced dry weight accumulation by the plants as well as development of productive tillering shoots and increased the shoot-root dry weight ratio.

Earth, Planet↗
PubMed2005

The last reaction producing brassinolide is catalyzed by cytochrome P-450s, CYP85A3 in tomato and CYP85A2 in Arabidopsis.

Brassinosteroids are steroidal hormones essential for the growth and development of plants. Brassinolide, the most biologically active brassinosteroid, has a seven-membered lactone ring that is formed by a Baeyer-Villiger oxidation of its immediate precursor castasterone. Despite its potential key role in controlling plant development, brassinolide synthase has not been identified. Previous work has shown that the formation of castasterone from 6-deoxocastasterone is catalyzed by members of the CYP85A family of cytochrome P-450 monooxygenases. A null mutation in the tomato Dwarf (CYP85A1) gene, extreme dwarf (d(x)), causes severe dwarfism due to brassinosteroid deficiency, but the d(x) mutant still produces fruits. Here, we show that d(x) fruits contain brassinolide at a higher level than wild-type fruits and that a new CYP85A gene, CYP85A3, is preferentially expressed in tomato fruits. Tomato CYP85A3 catalyzed the Baeyer-Villiger oxidation to produce brassinolide from castasterone in yeast, in addition to the conversion of 6-deoxocastasterone to castasterone. We also show that Arabidopsis CYP85A2, which was initially characterized as castasterone synthase, also has brassinolide synthase activity. Exogenous application of castasterone and brassinolide to the Arabidopsis cyp85a1/cyp85a2 double mutant suggests that castasterone can function as an active brassinosteroid but that its conversion into brassinolide is necessary for normal vegetative development in Arabidopsis. We postulate that castasterone is the major active brassinosteroid during vegetative growth in tomato, whereas brassinolide may play an organ-specific role in fruit development in this species.

Arabidopsis↗