Is Convergence at the Level of the Phenotype Mirrored Across the Genome? the Repeated Evolution of Glyphosate Resistance in the Common Morning Glory, Ipomoea purpurea

The common morning glory, Ipomoea purpurea, exhibits variation in nature for resistance to glyphosate, with some populations showing high survival post-herbicide application and others exhibiting high susceptibility. The pattern of resistance across the landscape appears to be a mosaic, such that resistance potentially evolved independently multiple times. We used a Rad-seq approach to identify the genetic basis of glyphosate resistance across independent populations followed by target-capture exome sequencing to identify potential causative SNPs. Using BayEnv and Bayescan, we identified approximately 80 loci potentially involved in resistance. Exome sequencing of predicted genes near these loci found five genes whose allele frequencies covary with resistance and show similar patterns among the spatially disjunct resistant populations. The data thus far suggest resistance is controlled by the same gene (or few genes) among resistant populations, indicating that the convergent herbicide resistance phenotype is due to a parallel genetic basis.