Population Genomics of Maize

One of the most explored crop plants in genomics studies is maize (Zea mays L.). It has served as a model for developing and incorporating biotechnology and genomics approaches in breeding programs of several other crop plants. From this perspective, the genomic information available in the last decades has helped geneticists and breeders better understand maize evolution and diversity, gene flow, admixture, and inbreeding and outbreeding depression, and identify genes and genetic variants related to many traits, increasing genetic gains in breeding programs. In this chapter, we present a review of population genomics aspects related to the genetic history of the origin and domestication of maize, the genes that underlined this process, and the possible introgressions that originated the multiple maize races known. We present the synthesis of information on genetic diversity of maize races and the heterotic groups that have become the genetic base of temperate and tropical commercial germplasms. The genomic diversity of maize, especially after the release of inbred line B73, is presented by focusing on the advances made regarding maize pan-genomes and epigenomics. We also discuss how population genomics helped maize breeding and highlight some results in genome-wide association studies and genomic selection, although these results are not yet fully exploited in maize germplasm conservation. Finally, we briefly present some future perspectives into the application of population genomics in maize conservation, selection, and breeding. Although many advances have already been made in population genomics of maize, the more we elucidate the multiple aspects of maize genetics, the more questions arise, unraveling new key insights into maize population genomics and breeding.