Auxinic herbicide-resistant (i.e., resistant to 2,4-D and MCPA) wild radish (Raphanus raphanistrum L.) was discovered in the Western Australian wheatbelt, providing an opportunity to integrate auxinic herbicide resistance into cultivated radish (R. sativus L.) using conventional breeding methods. It was hypothesized that the inheritance of auxinic herbicide resistance in wild radish is conferred by a single, dominant nuclear gene and, therefore, will be relatively easy to introgress from wild radish to cultivated radish; and the mechanism of auxinic herbicide resistance in wild radish is through an altered target-site. Visual injury data of the F2 progeny suggested that resistance was conferred by a quantitative trait with the susceptible allele(s) exhibiting dominance with minor cytoplasmically inherited genes masking the susceptible trait. In conclusion, the resistance allele(s) were quantitative and, thus, make selection for resistance difficult. Therefore, the introgression of the resistance allele(s) was not successfully completed. To determine the mechanism of resistance, the wild radish plants resistant WARR6-26 (R) and susceptible WARR7-5 (S) were treated with radiolabeled MCPA. There was no difference in metabolism of [14C]MCPA between R and S plants. Based upon the decline in the total 14C recovered over 72 h in R and S it was clear that both were “losing” [14C]MCPA; however, R plants were losing MCPA more rapidly. It was hypothesized that because R plants exude 14C more rapidly from their roots than S plants, this accounted for the resistance of R plants.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OGU.10214/4039 |
| Date | 03 October 2012 |
| Creators | Di Meo, Natalie L. |
| Contributors | Hall, J. Christopher |
| 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 | Thesis |
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