Bumble bee (Bombus impatiens) survival, pollen usage, and reproduction are not affected by oxalate oxidase at realistic concentrations in American chestnut (Castanea dentata) pollen.

Transgenic American chestnut trees expressing a wheat gene for oxalate oxidase (OxO) can tolerate chestnut blight, but as with any new restoration material, they should be carefully evaluated before being released into the environment. Native pollinators such as bumble bees are of particular interest: Bombus impatiens use pollen for both a source of nutrition and a hive building material. Bees are regular visitors to American chestnut flowers and likely contribute to their pollination, so depending on transgene expression in chestnut pollen, they could be exposed to this novel source of OxO during potential restoration efforts.

Transgenic American Chestnuts Do Not Inhibit Germination of Native Seeds or Colonization of Mycorrhizal Fungi.

The American chestnut () was once an integral part of eastern United States deciduous forests, with many environmental, economic, and social values. This ended with the introduction of an invasive fungal pathogen that wiped out over three billion trees. Transgenic American chestnuts expressing a gene for oxalate oxidase successfully tolerate infections by this blight fungus, but potential non-target environmental effects should be evaluated before new restoration material is released.

Chestnut, American (Castanea dentata (Marsh.) Borkh.).

The key to successful transformation of American chestnut is having the correct combination of explant tissue, selectable markers, a very robust DNA delivery system, and a reliable regeneration system. The most important components of this transformation protocol for American chestnut are the following: starting out with rapidly dividing somatic embryos, treating the embryos gently throughout the Agrobacterium inoculation and cocultivation steps, doing the cocultivation step in desiccation plates, and finally transferring the embryos into temporary-immersion bioreactors for selection. None of these departures from standard Agrobacterium transformation protocols is sufficient by itself to achieve transgenic American chestnut, but each component makes a difference, resulting in a highly robust protocol.

Comparisons of ectomycorrhizal colonization of transgenic american chestnut with those of the wild type, a conventionally bred hybrid, and related fagaceae species.

American chestnut (Castanea dentata [Marsh.] Borkh.) dominated the eastern forests of North America, serving as a keystone species both ecologically and economically until the introduction of the chestnut blight, Cryphonectria parasitica, functionally eradicated the species.

A threshold level of oxalate oxidase transgene expression reduces Cryphonectria parasitica-induced necrosis in a transgenic American chestnut (Castanea dentata) leaf bioassay.

American chestnut (Castanea dentata) was transformed with a wheat oxalate oxidase (oxo) gene in an effort to degrade the oxalic acid (OA) secreted by the fungus Cryphonectria parasitica, thus decreasing its virulence. Expression of OxO was examined under two promoters: a strong constitutive promoter, CaMV 35S, and a predominantly vascular promoter, VspB. Oxo gene transcription was quantified by RT-qPCR.