Maize domestication and gene interaction

Domestication is a tractable system for following evolutionary change. Under domestication, wild populations respond to shifting selective pressures, resulting in adaptation to the new ecological niche of cultivation. Due to the important role of domesticated crops in human nutrition and agriculture, the ancestry and selection pressures transforming a wild plant into a domesticate have been extensively studied. In Zea mays, morphological, genetic, and genomic studies have elucidated how a wild plant, the teosinte Zea mays subsp. parviglumis, was transformed into the domesticate Zea mays subsp. mays. Five major morphological differences distinguish these two subspecies, and careful genetic dissection has pinpointed the molecular changes responsible for several of these traits. But maize domestication was a consequence of more than just five genes, and regions throughout the genome contribute. The impacts of these additional regions are contingent on genetic background, both the interactions between alleles of a single gene and among alleles of the multiple genes that modulate phenotypes. Key genetic interactions include dominance relationships, epistatic interactions, and pleiotropic constraint, including how these variants are connected in gene networks. Here, we review the role of gene interactions in generating the dramatic phenotypic evolution seen in the transition from teosinte to maize.