10 VIRGINIA FORESTS Citizen Science Powers the Restoration of the American Chestnut Tree Once dominant in many upland forest ecosystems from Georgia to Maine, the American chestnut tree (Castanea dentata (Marsh.) Borkh., Fagaceae) has come to symbolize many things to many people. A critical food source for indigenous communities, wildlife, and subsequent waves of Euro-American settlers and their livestock, as well as a treasured multi-functional timber source, the chestnut is truly deserving of the title iconic. Its ecological role in forests of various management intensity, as well as its relationship with fire, has long been the subject of investigation, while continuous and future change in climates, disturbance, and other factors will mean that its return to the landscape will be decidedly different from its once-held position. Since its demise because of the introduced blight fungus (Cryphonectria parasitica), people have been undertaking vast breeding campaigns for disease resistance improvement in the context of federal, state, and non-profit groups. From the continental to the local, citizen science and local volunteers have been the lifeblood of many of these efforts. Read on to learn the latest about the science and people powering the return of the mighty chestnut, and how each person can become an integral participant in this grand conservation movement. Current Directions in American Chestnut Improvement for Disease Resistance The American Chestnut Foundation (TACF) was founded to develop a blight resistant American chestnut tree and reintroduce it into its native range throughout eastern North America. To develop a blight resistant tree, TACF implemented a backcross breeding program from the 1980s to the 2010s to integrate blight resistance from Chinese chestnut into the American chestnut. This breeding program was based on the idea that a small handful of genes is responsible for natural blight resistance in Chinese chestnut trees, which coevolved with the blight-causing fungus. Fast forward thirty years and the current breeding program is informed by genomic selection. Simply put, genomic selection is used to evaluate the genetic diversity within a breeding program through identification and analysis of specific DNA sequences, or genetic markers, along the individual’s genome. Genomic selection can predict the breeding value of offspring in a population by By Vasiliy Lakoba and Lauren Kerwien The American Chestnut Foundation’s flagship Meadowview Research Farms are in far southwestern Virginia. The above aerial view of the Price Research Farm at Meadowview shows breeding orchards and progeny tests at various stages of growth, all nestled in a mosaic of pasture and forestland. Much of the hybrid chestnut germplasm supplied to the citizen scientists of TACF state chapters originated in the Meadowview program, which started in the late 1980s. associating their traits, like disease resistance, with their genetic markers. To develop a breeding model informed by genomic selection, TACF first characterized the phenotypes of thousands of chestnut trees throughout the native range, focusing on blight resistance, Phytophthora root rot (PRR)
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