GNN - Genome News Network  
  Home | About | Topics
Genetic diversity in maize: SNP survey of chromosome 1

By Edward R. Winstead

 Printer Friendly

News by Topic

The diversity of DNA sequences among maize genomes is greater than that of humans or fruit flies, according to a survey of chromosome 1 in maize. On average, two randomly sampled maize DNA sequences have a single nucleotide polymorphism, or SNP, every 104 base pairs, the researchers estimate.

Brandon S. Gaut, of the University of California, Irvine, and colleagues sequenced 21 stretches along chromosome 1 for about two dozen varieties of maize. The sample included nine US inbred strains and 16 exotic strains, representing the plant's geographic and genetic diversity. Individual plants came from regions of Peru, Chile, Mexico, Guatemala, Uruguay, Venezuela, and the United States.

The researchers compared the inbred and exotic strains to assess the genetic consequences of domestication. The inbred strains retained 77 percent of the level of diversity found in the sample of exotics. "There is thus little statistical evidence that the inbred sample represents a significant loss of diversity compared with landraces at any one locus," the researchers write in Proceedings of the National Academy of Sciences.

Gaut and colleagues argue, however, that the reduction is statistically meaningful. The finding of a reduction differed from previous studies of maize diversity. "In the future, it will be interesting to address inconsistencies among marker systems," they write.

The statistical measure of genetic diversity of maize was 1.4 times that of the fly and 11 times that of humans, the researchers found.

M.I. et al. Patterns of DNA sequence polymorphism along chromosome 1 of maize (Zea mays ssp. mays L.). Proc. Natl. Acad. Sci. USA 98, 9161-9166 (July 31, 2001).

Back to GNN Home Page