In this work, we present the generation of plants that constitutively overexpress A. thalianad-LDH using the Cauliflower Mosaic Virus 35S (CaMV35S) promoter. d-LDH-overexpressing plants are able to metabolize and detoxify externally provided d-lactate and MG, while wild-type plants accumulate toxic levels of these metabolites. Consequently, transformants are able to grow and develop in the presence of increased of d-lactate in the media whereas the development of wild-type plants is arrested shortly after germination. These features were used to develop d-LDH as a marker that allows mutant selection in the next generation of transformed plants.