Westbrook et al. (2026) Science

More than a century after two introduced pathogens killed billions of American chestnut trees, introgression of resistance alleles from Chinese chestnuts has contributed to the recovery of self-sustaining populations. However, progress has been slow because of the complex genetic architecture of resistance. To better understand blight resistance, we compared reference genomes, gene expression responses, and stem metabolite profiles of the resistant Chinese and susceptible American chestnut species. To accelerate resistance breeding, we conducted large-scale phenotyping and genotyping in hybrids of these species. Simulation and inoculation experiments suggest that significant resistance gains are possible through selectively breeding trees with an average of 70 to 85% American chestnut ancestry. The resources developed in this work are foundational for breeding to create diverse restoration populations with sufficient disease resistance and competitive growth.

Westbrook JW, Malukiewicz J, Zhang Q, Sreedasyam A, Jenkins JW, Lakoba V, Fitzsimmons S, Van Clief J, Collins K, Hoy S, Stark C, Graboski L, Jenkins E, Saielli TM, Jarrett BT, Wigfield LJ, Kerwien LM, Wilbur C, Sandercock AM, Craddock JH, Kerio S, Zhebentyayeva T, Fan S, Thomas AM, Abbott AG, Nelson CD, Xia X, McKenna JR, Kell C, Williams M, Boston L, Plott C, Carle F, Swatt J, Ostroff J, Jeffers SN, McKeever K, Smith E, Ellis TJ, James JB, Sisco P, Newhouse A, Carlson E, Powell WA, Hebard FV, Scrivani J, Heverly C, Cipollini M, Clark B, Evans E, Levine B, Carlson JE, Goodstein D, Orebaugh J, Yang ZK, Martin MZ, Tannous J, Rush TA, Engle NL, Tschaplinski TJ, Grimwood J, Schmutz J, Holliday JA, Lovell JT. (2026) Genomic Approaches to Accelerate American Chestnut Restoration. Science. DOI:10.1126/science.adw3225