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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 90 (1994), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chitinases (EC 3.2.1.14) and β-1.3 glucanases (EC 3.2.1.39) have been known to play a vital role in the defense of plants against fungal pathogens. The pattern of induction of these two enzymes subsequent to infection by powdery mildew was studied in 10 pairs of near-isogenic lines of barley (Hordeum vulgare L.) which possess powdery mildew resistance genes. These isogenic lines have been grotiped according to their reaction to the fungus. The induction patterns varied between the resistant and the susceptible cultivars within each group and between different groups. More tsozymcs were induced in susceptible varieties of highly resistant groups and the overall levels and the number of isozymes of chitinases and β-1.3 glucanases were lower in groups with low resistance. The effect of powdery mildew infection and mechanical wounding on the cellular localization of chitinases and β-1.3 glucanases in barley leaves has also been studied. The 31 kDa leaf chitinase, L-CH2, and trace amounts of a 25 kDa chitinase. L-CH3. were present in healthy leaves. Wounding increased the levels of L-CH3 within I ft h. Powdery mildew infection increased the levels of L-CH3 both in intercellular fluid and in intracellular extract of leaves. A /3-I.3 glucanase. GH, also increased after infection and wounding. In infected barley leaves, GL-1 was present both in intercellular space and intracellular extract. It is concluded that powdery mildew resistance genes exhibit qualitative and quantitative differences in the expression of chitinases and β-1.3 glucanases. Further, chitinases and β-1.3 glucanases appear to be a response to active infection rather than the factors responsible for disease resistance.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; T. durum ; Aegilops longissimum ; Dasypyrum villosum ; Endonuclease ; Cytoplasm donor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To elucidate the phylogenetic relationships and cytoplasmic types, restriction endonuclease fragment patterns of chloroplast (cp) and mitochondrial (mt) DNAs isolated from two different accessions of Dasypyrum villosum (L.) candargy were compared with those of tetraploid wheat (Triticum durum Desf., PI265007), hexaploid wheat (Triticum aestivum L., cv Chinese Spring), Aegilops longissimum (S. and M., in Muschli) Bowden and Hordeum vulgare L. T. aestivum and T. durum had identical restriction patterns for their cp and mtDNAs in digestions with four different enzymes. Likewise, no differences were found between the restriction fragment patterns of two accessions of D. villosum. But, there were distinct differences in chloroplast and mitochondrial DNA restriction fragment patterns between D. villosum and tetraploid and hexaploid wheats. A. longissimum (G609) showed a similar pattern to those wheats for PstI digestion of cpDNA. Organellar DNA from Hordeum vulgare (cv Himalaya) showed a distinctly different restriction pattern from those of wheat and D. villosum. These results suggest that D. villosum is unlikely to be the donor of cytoplasm to wheats, and its cytoplasmic organelles were also different from those of A. longissimum.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2242
    Keywords: Key words Thaumatin-like protein ; PR-5 ; Rhizoctonia solani ; Sheath blight disease ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A 1.1-kb DNA fragment containing the coding region of a thaumatin-like protein (TLP-D34), a member of the PR-5 group, was cloned into the rice transformation vector pGL2, under the control of the CaMV 35S promoter. The Indica rice cultivars, ‘Chinsurah Boro II’, ‘IR72’, and ‘IR51500’ were transformed with the tlp gene construct by PEG-mediated direct gene transfer to protoplasts and by biolistic transformation using immature embryos. The presence of the chimeric gene in T0, T1, and T2 transgenic plants was detected by Southern blot analysis. The presence of the expected 23-kDa TLP in transgenic plants was confirmed by Western blot analysis and by staining with Coomassie Brilliant Blue. Bioassays of transgenic plants challenged with the sheath blight pathogen, Rhizoctonia solani, indicated that over-expression of TLP resulted in enhanced resistance compared to control plants.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2242
    Keywords: Key words  Triticum aestivum ; Genetic transformation ; Thaumatin-like protein ; Wheat scab ; Fluorescent in situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   The possibility of controlling wheat scab (caused by Fusarium graminearum Schw.) was explored by engineering wheat plants for constitutive expression of pathogenesis-related (PR) protein genes. A rice thaumatin-like protein (TLP) gene (tlp) and a rice chitinase gene (chi11) were introduced into the spring wheat cultivar ’Bobwhite’ by co-transformation of the plasmids pGL2ubi-tlp (ubiquitin/tlp//CaMV 35S/hpt) and pAHG11 (CaMV 35S/chi11//ubiquitin/bar). The transformation was by biolistic bombardment. Bialaphos was used as the selection reagent. The integration and expression of the tlp, bar, chi11 and hpt genes were analyzed by Southern, Northern and Western blot analyses. The four transgenes co-segregated in the T1 progeny of the transgenic plant and were localized at the telomeric region of the chromosome 6A long arm by sequential N-banding and fluorescent in situ hybridization (FISH) using pAHG11 or pGL2ubi-tlp as the probes. Only the transgenes tlp and bar, under the control of the ubiquitin promoter-intron, were expressed. No expression of the chi11 and hpt genes, controlled by the CaMV 35S promoter, was detected in T1 plants. After inoculation with conidia of F. graminearum, the symptoms of scab developed significantly slower in transgenic plants of the T1, T2 and T3 generations expressing the tlp gene than in non-transformed control plants. This is the first report of enhanced resistance to F. graminearum in transgenic wheat plants with constitutive expression of TLP.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2242
    Keywords: Key wordsTriticum aestivum ; Transformation ; Microprojectile bombardment ; Chitinase gene ; bar gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Our long-term goal is to control wheat diseases through the enhancement of host plant resistance. The constitutive expression of plant defense genes to control fungal diseases can be engineered by genetic transformation. Our experimental strategy was to biolistically transform wheat with a vector DNA containing a rice chitinase gene under the control of the CaMV 35 S promoter and the bar gene under control of the ubiquitin promoter as a selectable marker. Immature embryos of wheat cv ‘Bobwhite’ were bombarded with plasmid pAHG11 containing the rice chitinase gene chi11 and the bar gene. The embryos were subcultured on MS2 medium containing the herbicide bialaphos. Calli were then transferred to a regeneration medium, also containing bialaphos. Seventeen herbicide-resistant putative transformants (T0) were selected after spraying with 0.2% Liberty, of which 16 showed bar gene expression as determined by the phosphinothricin acetyltransferase (PAT) assay. Of the 17 plants, 12 showed the expected 35-kDa rice chitinase as revealed by Western blot analysis. The majority of transgenic plants were morphologically normal and self-fertile. The integration, inheritance and expression of the chi11 and bar genes were confirmed by Southern hybridization, PAT and Western blot analysis of T0 and T1 transgenic plants. Mendelian segregation of herbicide resistance was observed in some T1 progenies. Interestingly, a majority of the T1 progeny had very little or no chitinase expression even though the chitinase transgene was intact. Because PAT gene expression under control of the ubiquitin promoter was unaffected, we conclude that the CaMV 35 S promoter is selectively inactivated in T1 transgenic wheat plants.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Company
    Nature biotechnology 13 (1995), S. 686-691 
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] A 1.1 kb rice genomic DNA fragment, containing a chitinase gene under the control of the CaMV 35S promoter, was cloned into the rice transformation vector pGL2. After transformation of Indica rice protoplasts in the presence of polyethyleneglycol, plants were regenerated. The presence of the ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 18 (1997), S. 512-520 
    ISSN: 1432-0541
    Keywords: Key words. Parallel algorithms, Randomized (Las Vegas) string matching, %String Matching on Finite State Machines, Approximate Matching, Checking string matching algorithms.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Consider a text string of length n, a pattern string of length m, and a match vector of length n which declares each location in the text to be either a mismatch (the pattern does not occur beginning at that location in the text) or a potential match (the pattern may occur beginning at that location in the text). Some of the potential matches could be false, i.e., the pattern may not occur beginning at some location in the text declared to be a potential match. We investigate the complexity of two problems in this context, namely, checking if there is any false match, and identifying all the false matches in the match vector. We present an algorithm on the CRCW PRAM that checks if there exists a false match in O(1) time using O(n) processors. This algorithm does not require preprocessing the pattern. Therefore, checking for false matches is provably simpler than string matching since string matching takes $\Omega(\log\log m)$ time on the CRCW PRAM. We use this simple algorithm to convert the Karp—Rabin Monte Carlo type string-matching algorithm into a Las Vegas type algorithm without asymptotic loss in complexity. We also present an efficient algorithm for identifying all the false matches and, as a consequence, show that string-matching algorithms take $\Omega(\log\log m)$ time even given the flexibility to output a few false matches.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2242
    Keywords: Key words Chitinase ; Gene-silencing ; hpt-gene-silencing ; Rice ; Transcriptional silencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The inheritance and expression of a transgene locus consisting of multiple copies of a rice chitinase gene under the control of the CaMV 35S promoter was studied in the T3 and T4 generations of a transformed line that expressed the chitinase at a high level. All T3 progeny of a homozygous T2 parent expressed the chitinase constitutively at 3 weeks after germination, but a proportion of the progeny had undetectable levels of chitinase 8 weeks after germination, indicating silencing of the transgene. Transgene silencing was also observed among progeny of a hemizygous parent. However, we did not observe chitinase gene silencing among progeny of another homozygous line that expressed the transgenic chitinase at a five- to tenfold lower level. Thus, expression level, rather than copy number, of the transgene appears to be critical for silencing. Silencing was observed in the leaf, sheath, and root tissues of the plant, indicating that it is not restricted to specific tissues. Silencing was first observed in the youngest leaves and only later in the oldest leaves of the same plant. There was co-silencing of the selectable marker gene, hpt, which is also driven by the CaMV 35S promoter. Unlike the two transgenes (chitinase and marker), the resident homologous chitinase gene with seed-specific expression and two nonhomologous chitinase genes induced in the leaves upon pathogen infection were not silenced. The silent phenotype was inherited in the T4 generation plants, while progeny of expressing plants exhibited silencing. The chitinase transgene appeared intact, and no evidence for gross alterations or methylation of CCGG sites was found. The silent phenotype could not be reversed by treatment with 5-azacytidine. Northern blot analysis and nuclear run-on transcription studies indicated that silencing occurred at the transcriptional level. The implications of transgene silencing in genetic engineering of monocot plants for disease resistance are discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2242
    Keywords: Chloroplast DNA ; Sorghum bicolor (L.) ; Moench ; Male-sterile cytoplasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restriction endonuclease patterns of chloroplast DNA (cpDNA) were consistently distinguishable between fertile and male-sterile cytoplasms of sorghum [Sorghum bicolor (L.) Moench], whereas no differences in restriction patterns of cpDNA among male-sterile (A1) lines, including six isocytoplasmic strains, were revealed in this study. It is suggested that chloroplast DNA may contribute to the male sterility of A1 lines used currently in hybrid sorghum production.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Engineering with computers 12 (1996), S. 243-255 
    ISSN: 1435-5663
    Keywords: Finite element ; Mesh modification ; Triangular mesh refinement and derefinement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper presents a topological approach to improve the quality of unstructured triangular finite element meshes. Topological improvement procedures are presented both for elements that are interior to the mesh and for elements connected to the boundary. Optimal ordering of the topology improvement operations and their efficient implementation is also discussed. Several example meshes are included to demonstrate the effectiveness of the approach in improving element quality in a finite element mesh.
    Type of Medium: Electronic Resource
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