| Domestication provides an excellent model for understanding the evolution of quantitative traits due to strong morphological divergence that is often accompanied by profound genetics divergence between the domesticate and its ancestor. Here, we are interested in using maize domestication as a model for understanding genetic changes that distinguish maize from its ancestor teosinte. Beginning at a single gene level, we identified a gene called ZmYAB2.1 through quantitative trait locus (QTL) fine-mapping. ZmYAB2.1 was selected for lower expression in maize which led to shorter ear internode length and more compact grains on an ear for improving harvestability. Further characterization of ZmYAB2.1 revealed that this gene acts in a background dependent manner. Subsequently, we expanded our approach to multiple genes level by mapping QTLs for sexual conversion of the terminal lateral inflorescence in maize. We identified three QTLs (STAM1.1, STAM1.2 and STAM2.1) that are responsible for the sexual conversion and other related domestication traits. Additionally, we also narrowed STAM2.1 down to a 600 kb region with two candidate genes. As our perspective moved from a single gene to a network of multiple genes, we were keen on understanding the genetic changes during domestication on a broader scale. We sampled 18 traits in two large populations of teosinte and maize landrace for estimating additive and dominance genetic variances, genetic-by-environment variances, genetic correlations and genetic covariances. While we observed variable divergence among the 18 domestication traits, we identified a consistent pattern of reduced genetics variability in reproduction-related traits. We inferred weak selection intensities across all domestication traits and moderate genetic constraint during early domestication. We showed that selection for more grains along a single row on an ear would lead to the largest evolutionary gain in all domestication traits with minimal constraint. Overall, our approaches in studying maize domestication offer several different perspectives on the evolution of a major crop from a wild plant. |
