Assessing ectomycorrhizal associations on chestnut: Comparing transgenic, wild-type, a conventionally-bred hybrid, and related Fagaceae species

American chestnut (Castanea dentata) once dominated eastern U.S. forests prior to its demise following the introduction of Cryphonectria parasitica. Genetic transformation has been suggested as a method to produce chestnut trees with enhanced blight resistance. This project is an assessment of the potential non-target impact of an oxalate oxidase-expressing, transgenic American chestnut on associated ectomycorrhizal fungal communities. This is accomplished through a greenhouse bioassay that compares transgenic American chestnut to the wild-type, a conventionally-bred hybrid, and related Fagaceae species. The results demonstrate that the transgenic chestnut does not differ in EM fungal colonization compared to wild-type or hybrid chestnut, and environmental factors like soil site have a greater influence on EM presence than transgene expression. This work will be used to inform regulators regarding the environmental safety of transgenic American chestnut and contribute to the existing body of research regarding non-target impacts of transgenic forest trees.;Key Words: Castanea dentata, mycorrhizal fungi, non-target impact, greenhouse bioassay...