Journal Article

Genomic Screening for Artificial Selection during Domestication and Improvement in Maize

Masanori Yamasaki, Stephen I. Wright and Michael D. McMullen

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 100, issue 5, pages 967-973
Published in print October 2007 | ISSN: 0305-7364
Published online August 2007 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcm173
Genomic Screening for Artificial Selection during Domestication and Improvement in Maize

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background

Artificial selection results in phenotypic evolution. Maize (Zea mays L. ssp. mays) was domesticated from its wild progenitor teosinte (Zea mays subspecies parviglumis) through a single domestication event in southern Mexico between 6000 and 9000 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.

Scope

This review is a summary of research on the identification and characterization by population genetics approaches of genes affected by artificial selection in maize.

Conclusions

Analysis of DNA sequence diversity at a large number of genes in a sample of teosintes and maize inbred lines indicated that approx. 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 second 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 exhibiting evidence for artificial selection. Extended gene sequencing demonstrated a low false-positive rate in 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 if specific demographic conditions during domestication exist.

Keywords: Maize; Zea mays L. ssp. mays; teosinte; Zea mays subspecies parviglumis; agronomic traits; artificial selection; domestication; plant breeding; DNA sequence; genetic diversity; HKA (Hudson–Kreitman–Aguadé) test; bottleneck; coalescent simulation

Journal Article.  5301 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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