Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 57-62).

No description available.

Thirty-one tobacco introductions that were reported to display either a local lesion or a symptomless reaction to infection with tobacco mosaic virus (TMV) were screened for reaction to the virus (Chaplin and Gooding, 1969). Ten tobacco introductions (TI), TI 203, TI 407, TI 438, TI 450, TI 692, TI 1203, TI 1459, TI 1462, TI 1467, and TI 1500 were randomly chosen for further study to characterize their resistance to tobacco mosaic virus (TMV). Each TI line was crossed with susceptible cultivar K 326 to determine the mode of inheritance of resistance to TMV. The F2 progeny of TIs 1459, 1462, and 1500 segregated in a 3 local lesion:1 mosaic ratio, indicating that the gene governing resistance in these three TI lines was a single, dominant trait. The F2 progeny of TIs 203, 407, 438, 450, 692, 1203, and 1467 failed to segregate, only mosaic plants were observed. This would indicate that the gene(s) controlling resistance to TMV in these lines would not provide resistance for plant breeders to incorporate into a breeding program. Each TI line was also crossed with local lesion cultivar NC 567, which contains the N gene, in order to determine if the gene(s) governing resistance in the TI lines was allelic to the N gene in NC 567. The F2 progeny of TIs 1459 and 1462 did not segregate. All progeny displayed the local lesion reaction to TMV indicating that the gene governing resistance in these two lines is allelic to the N gene. The F2 progeny of the cross between TI 1500 and NC 567 segregated in a 15 local lesion: 1 mosaic ratio, which indicates that the gene controlling resistance in TI 1500 is not allelic to the N gene. When crossed with NC 567, the F2 progeny of TIs 407, 438 and 1467, segregated in a 3 local lesion: 1 mosaic ratio. No symptomless plants were observed. There was also segregation in the F2 progeny of the crosses between NC 567 and TIs 203, 450, 692, and 1203. However, the segregation was in no discernible ratio. Once again the F2 progeny of the crosses either displayed a local lesion or mosaic reaction and no symptomless progeny were observed. This would again indicate that the symptomless TI lines do no provide heritable resistance to TMV and therefore are not acceptable as an alternative source of resistance to TMV for the plant breeder. Tobacco introduction 1500 should be investigated further because a single, dominant trait that is not allelic to the N gene governs resistance to TMV in this line. / Master of Science

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 19, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. James E. Schoelz. Includes bibliographical references.

Due to the rapid destruction of native orchid habitats it has become necessary to house many endangered orchid species in greenhouse environments where enhanced spread of viral disease occurs due to the close contact between plants. This research was concerned with the construction of a library of genes whose expression is induced in response to viral challenge. In uncovering the genes that are activated during plant-pathogen interactions, it may be possible to manipulate these pathways to develop virus resistant orchids. Furthermore, this research will contribute additional information for the existing framework of plant-pathogen interactions of all plant species.In order to construct a library of genes expressed in response to viral infection, suppression subtractive hybridization was performed using the PCR-Select cDNA Subtraction Kit (CLONTECH, Palo Alto, CA) on Sophrolaeliacattleya Ginny Champion 'Riverbend' clones. RNA was isolated from plants that had been inoculated with the Odontoglossum ringspot virus (ORSV) and from control plants that had not been inoculated with ORSV. Following reverse transcription-PCR (RT-PCR) to obtain cDNA, cDNAs of the tester population (those cDNAs containing differentially expressed messages in response to ORSV) and the driver population (reference cDNAs from uninfected plants) were obtained. The two different cDNA populations are mixed together and hybridized. The sequences common to both populations were subtracted, leaving only the differentially expressed sequences available for PCR amplification.A library containing these genes was constructed, and one clone, chosen at random, was sequenced. Based on homology comparisons to known genes, we have cloned a gene that may contain a nucleotide binding site similar to that of the tobacco N gene, important for plant resistance to pathogens. In the near future, this clone will be used to construct probes for use in northern analysis to determine the timing and localization of the products of this gene. This information will aid in characterizing the function of the orchid N-gene and identifying other members of this signal cascade. In addition, many other clones await sequencing and similar characterization. / Department of Biology

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 87-91).

No description available.

Control and TMV-infected leaf tissues of three varieties of tomatoes, Marglobe, Moscow and Delicious, were analyzed for Ribulose Diphosphate Carboxylase (RuDPCase). The specific activity of RuDPCase based on protein concentration determined by peak area obtained with the Model E Ultracentrifuge, specific activity of RuDPCase based on protein concentration determined by Lowry's method, total amount of RuDPCase per gram fresh weight, total protein of plant leaves, total chlorophyll, and ratio of Chlorophyll a to Chlorophyll b were determined. Tobacco Mosaic Virus (TMV) infection resulted in an increase in specific activity of RuDPCase and the amount of total protein (at 2 days after inoculation). During the same time period there was a decrease in the total amount and total activity of RuDPCase in TMV-infected plants. The TMV infection appeared to also impair the synthesis of chlorophylls. The abnormal growth of TMV-infected plants appeared to be associated with the utilization of energy and organic substances from host plants for TMV-particle multiplication. As shown by changes in RuDPCase, photosynthesis in TMV-infected plants was disturbed.

Tobacco mosaic virus (TMV) is an extensively studied RNA virus that reduces quality and yield in commercially grown tobacco (Nicotiana tabacum L.). The virus is transmitted mechanically, although infections have been associated with contaminated seeds with the seed coat being the source of virus. Thus, TMV transmission is said to be seedborne (as opposed to true seed transmission where the embryo is infected). The objective of this study was to identify TMV concentrations in the three components of an individual tobacco seed: seed coat (SC), endosperm (ED), and embryo (EM). Six hundred seed from TMV infected K 326 flue-cured cultivar tobacco plants were carefully dissected into the three components. Total RNA was extracted from each sample and synthesized into cDNA for analysis. A quantitative real-time PCR (RT-qPCR) assay was developed to quantify viral titers in each component, while endpoint PCR confirmed RT- qPCR results and established a threshold viral cycle (Ct) value. Endpoint PCR results revealed viral accumulation in all three components of a tobacco seed. The highest concentration of TMV was in the SC, followed by ED and EM. A similar viral concentration gradient was observed in each individual tobacco seed from all three experimental plants. This is the first detection of TMV in tobacco embryos and suggests the virus can be seed transmitted. / Master of Science / Tobacco mosaic virus (TMV) is a widely studied plant virus that affects tobacco, tomato, pepper, and many other crops throughout the world. The virus is easily transmitted through contaminated tools or machinery, workers’ hands or clothing, or when an infected leaf comes into contact with an uninfected leaf. For years, TMV transmission was said to be seedborne, not seed transmitted, meaning that seedling infection comes from the infected external seed coat of the seed. Seed transmission of the virus has yet to be proven because of the difficulty to fully separate tobacco seed tissues. The objective of this study was to identify TMV concentrations in the three components of an individual tobacco seed: seed coat (SC), endosperm (ED), and embryo (EM). Six hundred seed from TMV infected tobacco plants were carefully dissected into the three components. Total RNA was extracted from each sample, and synthesized into cDNA for analysis. A quantitative real-time polymerase chain reaction (RT-qPCR) assay was developed to quantify viral concentrations in each component. Endpoint PCR was used to confirm the quantitative results of RT-qPCR. Results revealed TMV accumulation in all three components of a tobacco seed, the highest concentration detected in the SC, followed by ED and EM; this pattern was observed from each plant. This is the first report of TMV being detected in embryos of tobacco seed which suggests that TMV can be seed transmitted.