碩士 / 國立中興大學 / 生命科學系所 / 101 / Agrobacterium tumefaciens has a unique ability to transfer DNA from bacteria into eukaryotic cells. A. tumefaciens has a linear and a circular chromosomes, and two plasmids, the Ti-plasmid (tumor-inducing plasmid) and the cryptic plasmid. During A. tumefaciens infections, a DNA segment, called T-DNA (transferred DNA), from the Ti plasmid transfers from bacteria into plant cells, enters plant nucleus, finally integrates into plant chromosome and expresses oncogenes in the T-DNA regions. Due to the biosynthesis genes of auxin, cytokinin, and opine located in the wild-type T-DNA regions, the plant cells produce high
levels of plant hormones and opines after A. tumefaciens infections, leading to crown gall tumor formations in infected plants. Transformed plant cells synthesize and secrete significant quantities of particular opines which are then utilized by A. tumefaciens as a carbon and
sometimes nitrogen source. A. tumefaciens are usually classified on the basis of the opine they can catabolize. The most well studied strains are octopine, nopaline, and agropine. In this study, we characterized five poorly characterized wild-type Agrobacterium strains, 1D1108,
1D1460, 1D132, 1D1478, and 1D1487, from Northern America. Based on the Biolog assays,fatty acid analysis (fatty acid methyl esters profiles, FAME) and several physiological and
biochemical test results, these five strains belong to biovar 1 Agrobacterium tumefaciens.PCR analyses and DNA sequences of border regions of the five A. tumefaciens strains demonstrated that they are nopaline-type strains. We selected these five strains and NT1RE(pJK270), A208, C58, A348, Ach5, and 1D1609 to perform tumorigenesis assays on different plant families, including Leguminosae Cucurbitaceae, Asteraceae, Brassicaceae, Solanaceae, Apiaceae, Amaranthaceae, Lamiaceae and etc. Tumor assay results showed that nopaline-type strains caused more plant species to form tumors in the Brassicaceae family.
Octopine-type strains caused more plant species to produce tumors in some plant species of the Solanaceae and Asteraceae families. Arabidopsis transient transformation assay results also demonstrated that 1D1108 and 1D1460 strains showed higher and/or similar transformation efficiencies than other A. tumefaciens strains. In addition, 1D1108, 1D1460, 1D1609, and 1D1478 strains showed higher and/or similar transient transformation efficiencies than other A. tumefaciens strains in soybean and cowpea cotyledon explants transformation assays. The disarmed strains of 1D1108 and 1D1460 were obtained by the homologous recombination and could be further used to generate transgenic plants of certain recalcitrant but economically important crops.
| Identifer | oai:union.ndltd.org:TW/101NCHU5105004 |
| Date | January 2013 |
| Creators | En-Ting Wu, 吳恩婷 |
| Contributors | 黃皓瑄 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 134 |
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