A unified approach to assess the effects of herbicide resistance alleles on plant fitness

MARTIN MIGUEL VILA AIUB

Exposición; Herbicide Resistance Meeting; 2011

European Weed Research Society

Evolved herbicide resistance is usually assumed to be negatively associated with plant fitness, representing an evolutionary trade-off between the benefit of the resistance allele in the presence of the herbicide and its cost when the herbicide is removed1. This assumption is primarily based on the observation of evolutionary equilibrium at resistance alleles in herbicide unselected plant populations2. Quantifying costs of resistance provides insight into the cost of plant adaptation, has practical implications for weed management and provide a valuable input for modelling the trajectories of resistance alleles in weed populations and their equilibrium frequencies under a range of environmental conditions3. Fitness costs associated with herbicide resistance alleles are evident, but not universal among plant species. Paradoxically, in some cases, a fitness advantage has been observed, contradicting the growth-defence trade-off. For a proper assessment of costs it is necessary a correct experimental design and choice of plant traits which may range from biochemical to ecological scales. While some used experimental methods enable to determine the mechanistic bases of costs, others provide a better estimate of the impact of these costs on the trajectories of resistance alleles in plant populations4. The importance of control of genetic background and knowledge of the molecular basis of resistance for quantifying plant resistance costs are discussed.   1Stahl et al. (1999) Nature 400, 667-671. 2 Bergelson & Purrington (1996) American Naturalist 146, 536-558; Purrington (2000) Current Opinion in Plant Biology 3: 305-308. 3 Vila-Aiub, Neve & Powles (2009) New Phytologist 184, 751-767. 4 Lenormand et al. (1999) Nature 400, 861-864; Roux et al. (2006) Genetics 173, 1023-1031.