The research, published in the journal Science, analyzed the genomes of thousands of hybrid American chestnut trees that underwent a year of breeding and field testing for blight resistance.[1][3] Scientists sequenced the genomes of three key founder chestnut trees and compared them to real-world disease outcomes, demonstrating that resistance can be predicted solely from DNA data using genomic selection.[1][2][3] This method makes it possible to identify promising seedlings without the need for slow testing for fungal infection, thereby shortening breeding cycles.[1][3] Hybrids with 70 to 85% American chestnut show significant resistance to blight and root rot.[2][4] Chinese chestnut contributes to resistance by gene copy number variations, a different response to infection, and high levels of metabolites inhibiting the growth of the fungus.[2] Genomic selection makes it possible to maintain high genetic diversity and concentrate on trees with the growth form of the American chestnut.[1][3] The next generation of trees should have about double the average hardiness at 75% American origin and produce seed for renewal in a decade.[3]