TRACING THE CONTINENTAL DISPERSAL AND GENETIC BASIS OF HERBICIDE RESISTANCE IN A UBIQUITOUS AGRICULTURAL WEED

The evolution of herbicide resistance is one of the greatest challenges to sustainably perform agricultural activities. In addition to economic losses due to competition, herbicide resistance can impact the adoption of conservation agriculture practices such as no-tillage, reduce the price of the final product, and impact export markets due to seed contamination. The US leads the ranking of herbicide resistance evolution worldwide.Italian ryegrass (Lolium perenne L. ssp. multiflorum) is a winter annual grass weed, and herbicide resistance in this species hashas been identified in many US states. This project will assess whether the herbicide resistant populations identified throughout the US are genetically related, or whether they evolved independently. We will also identify the genes involved in herbicide resistance. Results from this project will elucidate whether the widespread resistance in Italian ryegrass is the results of widespread gene flow due to agricultural activities, or whether it is the result of local weed management practices. In addition, we will generate new knowledge in terms of how weeds can evolve under strong selection pressure from herbicides. Ultimately, our results could help minimize gene flow or local selection pressure on weed populations, as well as provide a starting point for the development of quick herbicide resistance diagnostics.