PubMed Central (PMC3 - NLM DTD)
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Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Mostrando recursos 101 - 120 de 50,776
101.
The Arabidopsis Plastidic Methionine Sulfoxide Reductase B Proteins. Sequence and Activity Characteristics, Comparison of the Expression with Plastidic Methionine Sulfoxide Reductase A, and Induction by Photooxidative Stress - Dos Santos, Christina Vieira; Cuiné, Stéphan; Rouhier, Nicolas; Rey, Pascal
Two types of methionine (Met) sulfoxide reductases (Msr) catalyze the reduction of Met sulfoxide (MetSO) back to Met. MsrA, well characterized in plants, exhibits an activity restricted to the Met-S-SO-enantiomer. Recently, a new type of Msr enzyme, called MsrB, has been identified in various organisms and shown to catalytically reduce the R-enantiomer of MetSO. In plants, very little information is available about MsrB and we focused our attention on Arabidopsis (Arabidopsis thaliana) MsrB proteins. Searching Arabidopsis genome databases, we have identified nine open reading frames encoding proteins closely related to MsrB proteins from bacteria and animal cells. We then analyzed...
102.
Local Coexpression Domains of Two to Four Genes in the Genome of Arabidopsis1[w] - Ren, Xin-Ying; Fiers, Mark W.E.J.; Stiekema, Willem J.; Nap, Jan-Peter
Expression of genes in eukaryotic genomes is known to cluster, but cluster size is generally loosely defined and highly variable. We have here taken a very strict definition of cluster as sets of physically adjacent genes that are highly coexpressed and form so-called local coexpression domains. The Arabidopsis (Arabidopsis thaliana) genome was analyzed for the presence of such local coexpression domains to elucidate its functional characteristics. We used expression data sets that cover different experimental conditions, organs, tissues, and cells from the Massively Parallel Signature Sequencing repository and microarray data (Affymetrix) from a detailed root analysis. With these expression data,...
103.
Computational Identification of 69 Retroposons in Arabidopsis1[w] - Zhang, Yujun; Wu, Yongrui; Liu, Yilei; Han, Bin
Retroposition is a shot-gun strategy of the genome to achieve evolutionary diversities by mixing and matching coding sequences with novel regulatory elements. We have identified 69 retroposons in the Arabidopsis (Arabidopsis thaliana) genome by a computational approach. Most of them were derivatives of mature mRNAs, and 20 genes contained relics of the reverse transcription process, such as truncations, deletions, and extra sequence additions. Of them, 22 are processed pseudogenes, and 52 genes are likely to be actively transcribed, especially in tissues from apical meristems (roots and flowers). Functional compositions of these retroposon parental genes imply that not the mRNA itself...
104.
Two Homologous ATP-Binding Cassette Transporter Proteins, AtMDR1 and AtPGP1, Regulate Arabidopsis Photomorphogenesis and Root Development by Mediating Polar Auxin Transport1 - Lin, Rongcheng; Wang, Haiyang
Light and auxin control many aspects of plant growth and development in an overlapping manner. We report here functional characterization of two closely related ABC (ATP-binding cassette) transporter genes, AtMDR1 and AtPGP1, in light and auxin responses. We showed that loss-of-function atmdr1 and atpgp1 mutants display hypersensitivity to far-red, red, and blue-light inhibition of hypocotyl elongation, reduced chlorophyll and anthocyanin accumulation, and abnormal expression of several light-responsive genes, including CAB3, RBCS, CHS, and PORA, under both darkness and far-red light conditions. In addition, we showed that the atmdr1-100 and atmdr1-100/atpgp1-100 mutants are defective in multiple aspects of root development, including...
105.
The AtRAD51C Gene Is Required for Normal Meiotic Chromosome Synapsis and Double-Stranded Break Repair in Arabidopsis1 - Li, Wuxing; Yang, Xiaohui; Lin, Zhenguo; Timofejeva, Ljudmilla; Xiao, Rong; Makaroff, Christopher A.; Ma, Hong
Meiotic prophase I is a complex process involving homologous chromosome (homolog) pairing, synapsis, and recombination. The budding yeast (Saccharomyces cerevisiae) RAD51 gene is known to be important for recombination and DNA repair in the mitotic cell cycle. In addition, RAD51 is required for meiosis and its Arabidopsis (Arabidopsis thaliana) ortholog is important for normal meiotic homolog pairing, synapsis, and repair of double-stranded breaks. In vertebrate cell cultures, the RAD51 paralog RAD51C is also important for mitotic homologous recombination and maintenance of genome integrity. However, the function of RAD51C in meiosis is not well understood. Here we describe the identification and...
106.
Genome-Wide Identification of Genes Expressed in Arabidopsis Pistils Specifically along the Path of Pollen Tube Growth1[w] - Tung, Chih-Wei; Dwyer, Kathleen G.; Nasrallah, Mikhail E.; Nasrallah, June B.
Plant reproductive development is dependent on successful pollen-pistil interactions. In crucifers, the pollen tube must breach the stigma surface and burrow through the extracellular matrix of the stigma epidermal cells and transmitting tract cells before reaching its ovule targets. The high degree of specificity in pollen-pistil interactions and the precision of directional pollen tube growth suggest that signals are continually being exchanged between pollen/pollen tubes and cells of the pistil that line their path. However, with few exceptions, little is known about the genes that control these interactions. The specialized functions of stigma epidermal cells and transmitting tract cells are...
107.
Rapid Array Mapping of Circadian Clock and Developmental Mutations in Arabidopsis1 - Hazen, Samuel P.; Borevitz, Justin O.; Harmon, Frank G.; Pruneda-Paz, Jose L.; Schultz, Thomas F.; Yanovsky, Marcelo J.; Liljegren, Sarah J.; Ecker, Joseph R.; Kay, Steve A.
Classical forward genetics, the identification of genes responsible for mutant phenotypes, remains an important part of functional characterization of the genome. With the advent of extensive genome sequence, phenotyping and genotyping remain the critical limiting variables in the process of map-based cloning. Here, we reduce the genotyping problem by hybridizing labeled genomic DNA to the Affymetrix Arabidopsis (Arabidopsis thaliana) ATH1 GeneChip. Genotyping was carried out on the scale of detecting greater than 8,000 single feature polymorphisms from over 200,000 loci in a single assay. By combining this technique with bulk segregant analysis, several high heritability development and circadian clock traits...
108.
Root Border-Like Cells of Arabidopsis. Microscopical Characterization and Role in the Interaction with Rhizobacteria1[w] - Vicré, Maïté; Santaella, Catherine; Blanchet, Sandrine; Gateau, Aurélien; Driouich, Azeddine
Plant roots of many species produce thousands of cells that are released daily into the rhizosphere. These cells are commonly termed border cells because of their major role in constituting a biotic boundary layer between the root surface and the soil. In this study, we investigated the occurrence and ultrastructure of such cells in Arabidopsis (Arabidopsis thaliana) using light and electron microscopy coupled to high-pressure freezing. The secretion of cell wall molecules including pectic polysaccharides and arabinogalactan-proteins (AGPs) was examined also using immunofluorescence microscopy and a set of anticarbohydrate antibodies. We show that root tips of Arabidopsis seedlings released cell...
109.
Electrophysiological Characterization of the Arabidopsis avrRpt2-Specific Hypersensitive Response in the Absence of Other Bacterial Signals1 - Pike, Sharon M.; Zhang, Xue-Cheng; Gassmann, Walter
The hypersensitive response (HR) is defined as rapid cell collapse at the infection site and often accompanies plant resistance. The physiological processes leading to HR are not well understood. Here, we report an electrophysiological characterization of bacterial HR caused by a single avirulence gene in the absence of other bacterial signals. We used dexamethasone (dex)-inducible transgenic Arabidopsis (Arabidopsis thaliana) plants containing the avrRpt2 gene from Pseudomonas syringae pv tomato. Membrane depolarization in these plants began 1 to 1.5 h after dex application, hours before electrolyte leakage. Progressive depolarization was a sensitive early indicator of HR that occurred only in Arabidopsis...
110.
Regulation of Plant Disease Resistance, Stress Responses, Cell Death, and Ethylene Signaling in Arabidopsis by the EDR1 Protein Kinase1 - Tang, Dingzhong; Christiansen, Katy M.; Innes, Roger W.
ENHANCED DISEASE RESISTANCE 1 (EDR1) encodes a CTR1-like kinase and was previously reported to function as a negative regulator of disease resistance and ethylene-induced senescence. Here, we report that the edr1 mutant displays enhanced stress responses and spontaneous necrotic lesions under drought conditions in the absence of pathogen, suggesting that EDR1 is also involved in stress response signaling and cell death regulation. Double mutant analysis revealed that these drought-induced phenotypes require salicylic acid but not ethylene signaling pathways. In addition, the edr1-mediated ethylene-induced senescence phenotype was suppressed by mutations in EIN2, but not by mutations in SID2, PAD4, EDS1, or...
111.
Loss-of-Function Mutations in Chitin Responsive Genes Show Increased Susceptibility to the Powdery Mildew Pathogen Erysiphe cichoracearum1[w] - Ramonell, Katrina; Berrocal-Lobo, Marta; Koh, Serry; Wan, Jinrong; Edwards, Herb; Stacey, Gary; Somerville, Shauna
Chitin is a major component of fungal walls and insect exoskeletons. Plants produce chitinases upon pathogen attack and chito-oligomers induce defense responses in plants, though the exact mechanism behind this response is unknown. Using the ATH1 Affymetrix microarrays consisting of about 23,000 genes, we examined the response of Arabidopsis (Arabidopsis thaliana) seedlings to chito-octamers and hydrolyzed chitin after 30 min of treatment. The expression patterns elicited by the chito-octamer and hydrolyzed chitin were similar. Microarray expression profiles for several genes were verified via northern analysis or quantitative reverse transcription-PCR. We characterized T-DNA insertion mutants for nine chito-oligomer responsive genes. Three...
112.
The Role of Salicylic Acid in the Induction of Cell Death in Arabidopsis acd111 - Brodersen, Peter; Malinovsky, Frederikke Gro; Hématy, Kian; Newman, Mari-Anne; Mundy, John
Salicylic acid (SA) is implicated in the induction of programmed cell death (PCD) associated with pathogen defense responses because SA levels increase in response to PCD-inducing infections, and PCD development can be inhibited by expression of salicylate hydroxylase encoded by the bacterial nahG gene. The acd11 mutant of Arabidopsis (Arabidopsis thaliana L. Heynh.) activates PCD and defense responses that are fully suppressed by nahG. To further study the role of SA in PCD induction, we compared phenotypes of acd11/nahG with those of acd11/eds5-1 and acd11/sid2-2 mutants deficient in a putative transporter and isochorismate synthase required for SA biosynthesis. We show...
113.
Tripeptidyl Peptidase II. An Oligomeric Protease Complex from Arabidopsis1 - Book, Adam J.; Yang, Peizhen; Scalf, Mark; Smith, Lloyd M.; Vierstra, Richard D.
The breakdown of most nuclear and cytoplasmic proteins involves their partial cleavage by the 26S proteasome followed by further disassembly to free amino acids by the combined action of endo- and exopeptidases. In animals, one important intermediate exopeptidase is tripeptidyl peptidase (TPP)II, which digests peptide products of the 26S proteasome and other endopeptidases into tripeptides. Here, we describe the purification and characterization of TPPII from Arabidopsis (Arabidopsis thaliana). Like its animal counterparts, Arabidopsis TPPII exists as a soluble, approximately 5- to 9-MD complex. Two related species of 153 and 142 kD are present in the purified preparations that are derived...
114.
Structural Complexity, Differential Response to Infection, and Tissue Specificity of Indolic and Phenylpropanoid Secondary Metabolism in Arabidopsis Roots1[w] - Bednarek, Pawe?; Schneider, Bernd; Svato, Ale; Oldham, Neil J.; Hahlbrock, Klaus
Levels of indolic and phenylpropanoid secondary metabolites in Arabidopsis (Arabidopsis thaliana) leaves undergo rapid and drastic changes during pathogen defense, yet little is known about this process in roots. Using Arabidopsis wild-type and mutant root cultures as an experimental system, and the root-pathogenic oomycete, Pythium sylvaticum, for infections, we analyzed the aromatic metabolite profiles in soluble extracts from uninfected and infected roots, as well as from the surrounding medium. A total of 16 indolic, one heterocyclic, and three phenylpropanoid compounds were structurally identified by mass spectrometry and nuclear magnetic resonance analyses. Most of the indolics increased strongly upon infection, whereas...
115.
Cloning and Functional Characterization of a Formin-Like Protein (AtFH8) from Arabidopsis1 - Yi, Kexi; Guo, Chunqing; Chen, Ding; Zhao, Binbin; Yang, Bin; Ren, Haiyun
The actin cytoskeleton is required for many cellular processes in plant cells. The nucleation process is the rate-limiting step for actin assembly. Formins belong to a new class of conserved actin nucleator, which includes at least 2 formin homology domains, FH1 and FH2, which direct the assembly of unbranched actin filaments. The function of plant formins is quite poorly understood. Here, we provide the first biochemical study of the function of conserved domains of a formin-like protein (AtFH8) from Arabidopsis (Arabidopsis thaliana). The purified recombinant AtFH8(FH1FH2) domain has the ability to nucleate actin filaments in vitro at the barbed end...
116.
The Arabidopsis Transcription Factor MYB12 Is a Flavonol-Specific Regulator of Phenylpropanoid Biosynthesis1 - Mehrtens, Frank; Kranz, Harald; Bednarek, Pawel; Weisshaar, Bernd
Comprehensive functional data on plant R2R3-MYB transcription factors is still scarce compared to the manifold of their occurrence. Here, we identified the Arabidopsis (Arabidopsis thaliana) R2R3-MYB transcription factor MYB12 as a flavonol-specific activator of flavonoid biosynthesis. Transient expression in Arabidopsis protoplasts revealed a high degree of functional similarity between MYB12 and the structurally closely related factor P from maize (Zea mays). Both displayed similar target gene specificity, and both activated target gene promoters only in the presence of a functional MYB recognition element. The genes encoding the flavonoid biosynthesis enzymes chalcone synthase, chalcone flavanone isomerase, flavanone 3-hydroxylase, and flavonol synthase...
117.
Light-Dark Changes in Cytosolic Nitrate Pools Depend on Nitrate Reductase Activity in Arabidopsis Leaf Cells1[w] - Cookson, Sarah J.; Williams, Lorraine E.; Miller, Anthony J.
Several different cellular processes determine the size of the metabolically available nitrate pool in the cytoplasm. These processes include not only ion fluxes across the plasma membrane and tonoplast but also assimilation by the activity of nitrate reductase (NR). In roots, the maintenance of cytosolic nitrate activity during periods of nitrate starvation and resupply (M. van der Leij, S.J. Smith, A.J. Miller [1998] Planta 205: 6472; R.-G. Zhen, H.-W. Koyro, R.A. Leigh, A.D. Tomos, A.J. Miller [1991] Planta 185: 356361) suggests that this pool is regulated. Under nitrate-replete conditions vacuolar nitrate is a membrane-bound store that can release nitrate to...
118.
The Involvement of Gibberellin 20-Oxidase Genes in Phytochrome-Regulated Petiole Elongation of Arabidopsis - Hisamatsu, Tamotsu; King, Rod W.; Helliwell, Chris A.; Koshioka, Masaji
Long day (LD) exposure of rosette plants causes rapid stem/petiole elongation, a more vertical growth habit, and flowering; all changes are suggestive of a role for the gibberellin (GA) plant growth regulators. For Arabidopsis (Arabidopsis thaliana) L. (Heynh), we show that enhancement of petiole elongation by a far-red (FR)-rich LD is mimicked by a brief (10 min) end-of-day (EOD) FR exposure in short day (SD). The EOD response shows red (R)/FR photoreversibility and is not affected in a phytochrome (PHY) A mutant so it is mediated by PHYB and related PHYs. FR photoconversion of PHYB to an inactive form activates...
119.
Brassinosteroid Homeostasis in Arabidopsis Is Ensured by Feedback Expressions of Multiple Genes Involved in Its Metabolism - Tanaka, Kiwamu; Asami, Tadao; Yoshida, Shigeo; Nakamura, Yasushi; Matsuo, Tomoaki; Okamoto, Shigehisa
Homeostasis of brassinosteroids (BRs) is essential for normal growth and development in higher plants. We examined responsiveness of 11 BR metabolic gene expressions to the decrease or increase of endogenous BR contents in Arabidopsis (Arabidopsis thaliana) to expand our knowledge of molecular mechanisms underlying BR homeostasis. Five BR-specific biosynthesis genes (DET2, DWF4, CPD, BR6ox1, and ROT3) and two sterol biosynthesis genes (FK and DWF5) were up-regulated in BR-depleted wild-type plants grown under brassinazole, a BR biosynthesis inhibitor. On the other hand, in BR-excessive wild-type plants that were fed with brassinolide, four BR-specific synthesis genes (DWF4, CPD, BR6ox1, and ROT3) and...
120.
New Arabidopsis Recombinant Inbred Lines (Landsberg erecta × Nossen) Reveal Natural Variation in Phytochrome-Mediated Responses1 - Magliano, Teresa M. Alconada; Botto, Javier F.; Godoy, A. Veronica; Symonds, V. Vaughan; Lloyd, Alan M.; Casal, Jorge J.
We used 52 Arabidopsis (Arabidopsis thaliana) accessions and developed a new set of 137 recombinant inbred lines between Landsberg erecta (Ler) and Nossen (No-0) to explore the genetic basis of phytochrome-mediated responses during deetiolation. Unexpectedly, most accessions showed weak or moderate hypocotyl growth and cotyledon unfolding responses to pulses of far-red light (FR). Crosses between Columbia and No-0, two accessions with poor response, segregated seedlings with unfolded cotyledons under pulsed FR, suggesting the occurrence of accession-specific loci in the repression of morphological responses to weak light signals. Confirming the latter expectation, mapping of responses to pulsed FR in the Ler...
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