Overexpression of a Native Gene Encoding 5-Enolpyruvylshikimate-3-Phosphate Synthase (EPSPS) May Enhance Fecundity in Arabidopsis thaliana in the Absence of Glyphosate

Premise of research. Strong environmental selection pressures can lead to rapid adaptation and the opportunity to study evolutionary dynamics in real time. A prime example is the recent evolution of resistance to the herbicide glyphosate, the active ingredient in Roundup, in more than 35 weed species. Mechanisms for glyphosate resistance include gene amplification and overproduction of its target enzyme, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), but little is known about whether these genetic changes are associated with differing fitness in glyphosate-free environments. Such fitness effects could have major implications for anticipated changes in the frequency of resistance traits without continued exposure to the selective pressure.Methodology. We used transgenic Arabidopsis thaliana as a model system to test for the effects of overproducing EPSPS on plant growth and reproduction. In a previous study, we developed six independent transgenic lines that overexpress a native EPSPS gene driven by ...