Submitted to: Annals Of Botany
Publication Type: Review article
Publication Acceptance Date: 7/3/2007
Publication Date: 8/18/2007
Citation: Yamasaki, M., Wright, S., Mcmullen, M.D. 2007. Genomic screening for artificial selection during domestication and improvement in maize. Annals Of Botany. 100:967-973. Interpretive Summary:
Technical Abstract: Artificial selection results in phenotypic evolution. Maize (Zea mays subspecies mays) was domesticated from its wild progenitor teosinte (Zea mays subspecies parviglumis) through a single domestication event in southern Mexico between 6,000 and 9,000 years ago. This domestication event resulted in the original maize landrace varieties. The landraces provided the genetic material for modern plant breeders to select improved varieties and inbred lines by enhancing traits controlling agricultural productivity and performance. Artificial selection during domestication and crop improvement involved selection of specific alleles at genes controlling key morphological and agronomic traits, resulting in reduced genetic diversity relative to unselected genes. In this review, we summarize research on the identification and characterization of genes affected by artificial selection in maize by population genetics approaches. Analysis of DNA sequence diversity at a large number of genes in a sample of teosintes and maize inbred lines indicated that ~2% of maize genes exhibit evidence of artificial selection. The remaining genes give evidence of a population bottleneck associated with domestication and crop improvement. In a study to efficiently identify selected genes, the genes with zero sequence diversity in maize inbreds were chosen as potential targets of selection and sequenced in diverse maize landraces and teosintes, resulting in about half of candidate genes being significant for artificial selection. Extended gene sequencing demonstrated a low false-positive rate to the approach. The selected genes have functions consistent with agronomic selection for plant growth, nutritional quality and maturity. Large scale screening for artificial selection allows identification of genes of potential agronomic importance even when gene function and the phenotype of interest are unknown. These approaches should also be applicable to other domesticated species.