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Ergot of nut sedge in South AfricaVan der Linde, Ella Johanna 04 August 2008 (has links)
Please read the abstract in the section 00front of this document / Thesis (PhD)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted
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Epidemiology and biology of Sclerotium bataticola taub. on several hosts.Chan, James Yu-Ho. January 1965 (has links)
No description available.
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Evolution of a gene for pathogenicity: endo-pectate lyaseAllen, Caitilyn January 1987 (has links)
Erwinia carotovora subsp. Carotovora (Ecc) and Erwinia carotovora subsp. Atroseptica (Eca) are plant pathogenic bacteria that cause soft rot disease of many plant species and blackleg disease of potatoes, respectively. Ecc and Eca attack plants by means of a group of extracellular plant tissue-degrading enzymes. which rapidly breaks down the pectic polymers that form a structurally important part of the plant cell wall, is considered central to soft rot pathogenesis. In this work, I isolated and studied the genes encoding this enzyme from Ecc and Eca. A clone library of Ecc strain EC14 was constructed using cosmid PLAFR3. This library contains 2,200 clones with an average insert size of 27 kilobases of DNA and included a proteolytic clone, five cellulolytic clones, and ten pectolytic clones. The proteolytic clone was used to complement a Tn5-induced protease mutant of Ecc; the complemented mutant was restored to near-wild type phenotype. Six of the pectolytic clones hybridized to a probe from a. previously isolated extracellular endo-pectate-pectate lyase gene from Ecc; one pectolytic clone had homology to a previously isolated clone encoding endo-polygalacturonase: three clones showed no relationship to either of the previously characterized Ecc pectolytic enzyme genes. A clone encoding the major endo-pectate lyase gene from Ecc was chosen for subcloning and further study. I used the plasmid vector pBR322 to construct a clone bank of Eca strain SRB; of the 1700 clones screened, five were pectolytic. Two of the Eca pectolytic. clones had homology to the Ecc endo-pectate lyase gene; upon examination, they proved to contain the same insert in opposite orientations. The Ecc endo-pectate lyase had a pI of 9. 5 and a molecular weight of 33,000; the analogous Eca endo-pectate lyase had a pI of 9.2 and a molecular weight of 31,000. Both enzymes required a divalent cation for activity (preferring Ca2+ over Mg2+ over Mn²⁺. The restriction endonuclease maps of the two clones did not have any tested sites in common. These differences suggest that although these two genes may have originated from a common ancestral gene, considerable divergence has taken place. I analyzed the fine structure of the Ecc endo-pectate lyase gene by DNA sequencing. The coding region of the gene is preceded by E. coli-type -10 and -35 sequences and encodes an unmodified protein of 281 amine acids. A typical secretion signal peptide is not present. / Ph. D.
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Soilborne with an aerial habitat characterization of Phytophthora species recovered from nursery and vegetable production in Tennessee /Donahoo, Ryan S. January 2008 (has links) (PDF)
Thesis (Ph. D.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Mar. 10, 2009). Thesis advisor: Kurt H. Lamour. Vita. Includes bibliographical references.
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Damping OffOlsen, Mary W., Young, Deborah 01 1900 (has links)
2 pp. / Originally published: 1998 / Damping off is caused by several different fungi under different environmental conditions. The fungi include Pythium, Rhizoctonia solani, and Thielaviopsis basicola. This article discusses the symptoms, environmental conditions, diseases, prevention and control methods for the damping-off caused by fungi.
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Developing a sensitive, high-throughput tool for rapid detection of agronomically important seed-borne pathogens of tomatoCarmichael, Deborah Jo 31 January 2013 (has links)
The limited specificity, sensitivity and multiplex capacity of detection techniques currently available
for important seed-borne pathogens of tomato is a significant risk for the global tomato trade and
production industry. These pathogens can be associated with seed at low concentrations but, due to
their highly virulent nature, these low levels can be sufficient to infect germinating seedlings and
spread to neighbouring plants and fields, potentially causing epidemics and economic losses. In this
study, detection techniques currently available for phytodiagnostics were evaluated for the capacity
to accurately detect and identify five agronomically important seed-borne pathogens of tomato:
Pepino mosaic virus (PepMV), Tomato mosaic virus (ToMV), Clavibacter michiganensis subsp.
michiganensis (Cmm), Xanthomonas campestris pv. vesicatoria and Pseudomonas syringae pv.
tomato. A prototype diagnostic microarray was also designed in an attempt to develop a tool that
could simultaneously detect these five seed-borne pathogens from a single sample. Viral detection
based on serological techniques was rapid, accurate and reliable but only detected a single pathogen
per assay and required supplementary bioassays to indicate the viability of detected viral pathogens.
Selective media plating for bacterial detection demonstrated unreliable recovery of targeted
bacteria from infected seed and leaf samples and required supplementary tests to validate the
identity of presumptive positives. Assays were lengthy, laborious and sometimes too ambiguous for
accurate diagnosis of bacterial pathogens. Nucleic acid-based technologies demonstrated improved
sensitivity and specificity for detection of targets from pure culture, leaf and seed extracts,
compared to conventional and serological methods, yet also required supplementary bioassays or
media assays to validate the viability of detected pathogens. Amplification efficiency however, was
affected by the presence of PCR inhibitors and despite positive detection, variable banding intensity
in electrophoretic analysis of amplified products necessitated the use of reference cultures to
validate diagnosis. The developed microarray incorporated 152 pathogen-specific and control probes
to facilitate diagnosis and taxonomic classification of detected pathogens. The array was challenged
with pure culture extracts of the five target pathogens, selected related and non-target, unrelated
pathogens of tomato. Positive detection of each of the pathogens was demonstrated but the
production of hybridisation signals was highly variable and extremely sensitive to minor technical
differences. Each of the five pathogens were successfully detected in combination proving that
different classes of seed-borne pathogens could be detected from a single sample using the
developed microarray. This prototype microarray has good potential for phytodiagnostic screening
of the five targeted pathogens, and further validation, optimisation and extension for testing tomato
seed samples may facilitate incorporation of this array into standard diagnostic protocols.
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Celery blackheart occurrence during growth as influenced by light quality and nutrition.Guévin, José. January 1981 (has links)
No description available.
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Biology and epidemiology of Australian grapevine phytoplasmasConstable, Fiona Elizabeth. January 2002 (has links) (PDF)
Includes bibliographical references (leaves 158-180) Appendix A. Vineyard disease survey maps -- appendix B. Log linear graphs
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Biology and epidemiology of Australian grapevine phytoplasmas / Fiona Elizabeth Constable.Constable, Fiona Elizabeth January 2002 (has links)
Includes bibliographical references (leaves 158-180) / xiii, [220] leaves : ill. (col.), maps ; 30 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2002
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Novel inducible phytochemical defences against plant parasitic nematodes / Imelda Rizalina Soriano.Soriano, Imelda Rizalina January 2004 (has links)
"August 2004" / Bibliography: leaves 146-169. / vi, 169 leaves : ill, (some col.), photos (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2004
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