Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Review Article
Publication Acceptance Date: 5/29/2013
Publication Date: 9/4/2013
Citation: Flint Garcia, S.A. 2013. Genetics and consequences of crop domestication. Journal of Agricultural and Food Chemistry. 61:8267-8276.
Interpretive Summary: All the world’s major crop species were domesticated from wild relatives thousands of years ago in various regions around the world. Humans imposed selection on these wild populations in order to make the crops more reliable, harvesting easier, and the food taste better. As a result, the form of the plant and the seeds or the fruit have undergone striking transformations. For example, wild tomato growing in Mexico or Peru resembles a very small cherry tomato. Over thousands of years, humans selected for larger fruit with varying shapes and colors, resulting in the amazing diversity of tomato cultivars available to gardeners and commercial producers today. Likewise, corn has a unique domestication and breeding history. The wild ancestor of corn, teosinte, was domesticated 9000 years ago in southern Mexico as a result of human selection for dramatic changes in the plant, ear, and kernel morphology. Teosinte is a bushy plant, with about one hundred small, cob-less ears that bear small seeds enclosed in a stony fruitcase. Human selection for single-stalk plants carrying one or two ears with hundreds of large, exposed kernels has resulted in the modern plant form. For all crops, human selection has profound effects on the genetic diversity of the crop that may impact its productivity. An understanding of the domestication and breeding history of each crop and the genetic consequences of this history can play an important role in increasing productivity in today’s agricultural systems.
Technical Abstract: Phenotypic variation has been manipulated by humans during crop domestication, which occurred primarily between 3,000 and 10,000 years ago in the various centers of origin around the world. The process of domestication has profound consequences on crops, where the domesticate has moderately reduced genetic diversity relative to the wild ancestor across the genome, and severely reduced diversity for genes targeted by domestication. The question that remains is whether reduction in genetic diversity has impacted crop production today. A case study in maize (Zea mays) demonstrates the application of understanding relationships between genetic diversity and phenotypic diversity in the wild ancestor and the domesticate. As an outcrossing species, maize has tremendous genetic variation. The complementary combination of genome-wide association mapping (GWAS) approaches, large HapMap datasets, and germplasm resources are leading to important discoveries of the relationship between genetic diversity and phenotypic variation, and the impact of domestication on trait variation.