The success of modern maize breeding derives from the development of hybrid maize breeding programs begun in the first half of the 20th century. Since then, much of the seven-fold increase in yield can be attributed to the tolerance of increased planting density and an increased density. To investigate the genetic impacts of selection during breeding and identify the key genes contributing to adaptation to increased planting density, Wang Haiyang’s team conducted a comprehensive analysis of the genomic and phenotypic changes associated with modern maize breeding through chronological sampling of 350 elite inbred lines representing multiple eras of germplasm from both China and the United States. They documented several convergent phenotypic changes in both countries. Using genome-wide association and selection scan methods, they identified 160 loci underlying adaptive agronomic phenotypes and more than 1,800 genomic regions representing the targets of selection during modern breeding. This work demonstrates the use of the breeding-era approach for identifying breeding signatures and lays the foundation for future genomics-enabled maize breeding.

Morphological trait improvement during modern maize breeding