A plan to diversify a transgenic blight‐tolerant American chestnut population using citizen science.

Shared with the Chestnut Growers of The American Chestnut Foundation on behalf of Jared Westbrook  — Mon 7/22/2019 

This article summarizes the rationale for TACF and ESF’s plans to outcross transgenic trees to wild trees to diversify the blight-tolerant population for restoration. We are currently in the second generation of outcrossing to wild trees. We plan to outcross the second generation trees over three additional generations to minimize inbreeding in the population. We plan to use DNA markers to select against the transgenic founder trees genome and to maximize genome inheritance from wild trees. We want to ensure
that the population has enough genetic diversity to adapt to broad geographical range and a changing climate.

TACF will need help of chapter members to find and propagate 1,000 wild type American chestnut from across the species range. These wild type trees can be used both for diversifying transgenic populations and for creating new backcross lines. The general protocol for collecting scion from wild trees is: 

1. Document the location of the tree and take a picture using treeSnap or the tree locator form on
2. Mark the tree with a forestry crayon or with a tag so that you can identify it in the winter
3. Revisit the tree in the winter and collect 5-10 pieces of scion wood. Scionwood should be last years
growth, about pencil width diameter, disease free, with dormant buds.
4. Ship scion wood to Meadowview or Penn State for propagation if you do not plan to propagate yourself.