Alopecurus myosuroides, a problematic weed of UK winter cereals, is predominantly controlled by post-emergent herbicides with ALS and ACCase modes of action (MOA). Evolved resistance to these MOA - endowed by the mechanisms of targetsite (TSR) and/or enhanced metabolism (EMR) – threatens the sustainable production of winter cereals in the UK. This project aims to establish the frequency of ALS and ACCase resistance in UK populations of A. myosuroides and the factors that drive its evolution. From a 2011 survey of 92 UK A. myosuroides populations, mesosulfuron-methyl + iodosulfuron-methyl-sodium (ALS) resistance was confirmed in 81 populations; all 92 populations exhibited clodinofop-propargyl (ACCase) resistance. To understand how management affects resistance evolution, seventeen populations from the 2011 survey were resampled (2012–2014) so that estimated frequencies of phenotypic resistance, TSR and EMR could be compared to weed management histories. Fields in which spring crops were more frequently planted possessed A. myosuroides that exhibited lower levels of phenotypic resistance to both ALS and ACCase MOA. A simulation model was developed to describe A. myosuroides herbicide resistance evolution. However, this model could not be validated when parameterized with resistance and management data collected from the UK. In the 2011 survey, homozygous Pro-197-Thr ALS TSR mutations were absent. Phenotyping, germination, and genotyping experiments of plants from controlled heterozygous Pro-197-Thr crosses confirmed that there is a lethality associated with homozygous Pro-197-Thr mutations. To test the hypothesis that preexisting ACCase EMR increases the rate of ALS EMR selection, four A. myosuroides populations – three with ACCase EMR and one without - were selected over two generations with ALS herbicide. From dose-response analyses of survival, the three populations with ACCase EMR exhibited significant increases in ED50 values after selection, whereas the population without ACCase EMR did not.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:682955 |
| Date | January 2015 |
| Creators | Knight, Craig Martin |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/77761/ |
Page generated in 0.002 seconds