Genomic approaches to accelerate American chestnut restoration
Jared W. Westbrook, Joanna Malukiewicz, Qian Zhang, Avinash Sreedasyam, Jerry Jenkins, Vasiliy T. Lakoba, Sara F. Fitzsimmons, Jamie Van Clief, Kendra Collins, Stephen Hoy, Cassie Stark, Lake E. Graboski, Eric V. Jenkins, Thomas M. Saielli, Benjamin Jarrett, Lucinda Wigfield, Lauren M. Kerwien, Ciera Wilbur, Alexander M. Sandercock, J. Hill Craddock, Susanna Keriö, Tetyana Zhebentyayeva, Shenghua Fan, Austin Thomas, Albert G. Abbott, C. Dana Nelson, Xiaoxia Xia, James McKenna, Caleb Kell, Melissa Williams, LoriBeth Boston, Christopher Plott, Florian Carle, Jack Swatt, Jack Ostroff, Steven N. Jeffers, Kathleen McKeever, Erica Smith, Thomas James Ellis, Joseph B. James, Paul H. Sisco, Andrew E. Newhouse, Erik Carlson, William A. Powell, Frederick V. Hebard, John A. Scrivani, Caragh Heverly, Martin L. Cipollini, B. K. Clark, Eric J. Evans, Bruce Levine, John E. Carlson, David Goodstein, Jack Orebaugh, Zamin K. Yang, Madhavi Z. Martin, Joanna Tannous, Tomás A. Rush, Nancy L. Engle, Timothy J. Tschaplinski, Jane Grimwood, Jeremy Schmutz, Jason Holliday, John T. Lovell
Abstract
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.