Intentional introgression of a blight tolerance transgene to rescue the remnant population of American chestnut

In contrast to many current applications of biotechnology, the intended consequence of the American Chestnut Research & Restoration Project is to produce trees that are well‐adapted to thrive not just in confined fields or orchards, but throughout their natural range. Our primary focus is on disease tolerance, but we believe it will also be critically important that optimal restoration trees should have robust genetic diversity and resilience, which can be supplied by a full complement of their wild‐type genes. Chestnut restoration offers a unique case study because many restoration or intervention options have been attempted: doing nothing, planting non‐native chestnut species, planting hybrids, mutagenesis (exposing seeds to high levels of radiation to induce random mutations), backcross breeding, and now genetic engineering. Any of these techniques may be advantageous independently or in combinations, depending on the specific goals of land managers or restoration practitioners, but genetic engineering offers a unique opportunity to enhance blight tolerance while minimizing other changes to the genome.