A two-component transposable element system consisting of a stabilized Activator (Acst) and a chimeric Dissociation (Ds) element has been introduced into the genome of Brassica napus. This Acst/ Ds system incorporates the use of several highly effective screenable and selectable markers. One of these markers is the maize Lc gene, a transcriptional regulator of flavonoid biosynthetic genes. This substrate-independent screenable marker was tested for the first time in B. napus and I show that when overexpressed, there is augmented trichome production and a light-dependent, enhanced accumulation of anthocyanins in B. napus plants. The phenotypes are expressed under a wide range of conditions, are visually distinct, and are observed throughout plant development. When used as a visual marker for the Acst element, Lc B. napus plants were rapidly identified among F2 segregating populations. As part of my goal to develop a very efficient Acst/Ds system for use in B. napus, a conditional negative selectable marker, the E. coli codA gene, was also tested for the first time in B. napus. This was done because use of a substrate-dependent negative selectable marker can facilitate the rapid and reliable identification of stable Ds transposition events when used as a marker for the Acst T-DNA. The enzyme cytosine deaminase, encoded by the codA gene, catalyzes the deamination of the non-toxic compound 5-fluorocytosine (5-FC) to the highly toxic compound 5-fluorouracil. In codA transformed B. napus seedlings, expression of cytosine deaminase results in a severe suppression of growth and this phenotype is dependent on the presence of the 5-FC substrate. Wild-type seedlings, however, lack endogenous cytosine deaminase activity and appear unaffected by the presence of 5-FC in the growth media. These results indicate that codA has the potential to be used effectively in B. napus as a substrate-dependent negative selectable marker for the Acst T-DNA. To determine if Ac transposase cou
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.37867 |
| Date | January 2001 |
| Creators | Babwah, Andy Videsh. |
| Contributors | Waddell, Candace S. (advisor), Brown, G. G. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001845381, proquestno: NQ75606, Theses scanned by UMI/ProQuest. |
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