Three new reports in Nature Genetics describe the maize genome. First, researchers led by Doreen Ware at Cold Spring Harbor Laboratory report on their whole-genome surveys of a number of Zea mays lines and a related genus, Tripsacum. Ware and her team identified 55 million SNPs and found that structural variation is common in Z. mays. Additionally, they say that the Tripsacum genome has a number of transposable elements in its genome, making it larger. Ware and her team add that their HapMap2 dataset will also serve as a resource for further study.
Another team, this one led by the University of California, Davis' Jeffrey Ross-Ibarra, examined maize population genomics using genome-wide resquencing data from 75 domesticated and wild strains of corn. "We find evidence of recovery of diversity after domestication, likely introgression from wild relatives, and evidence for stronger selection during domestication than improvement," Ross-Ibarra's team writes. They add that "we find evidence both consistent with removal of cis-acting variation during maize domestication and improvement and suggestive of modern breeding having increased dominance in expression while targeting highly expressed genes."
Finally, researchers from China Agricultural University in Beijing report their sequencing of a number of inbred maize lines. "The results show that modern breeding has introduced highly dynamic genetic changes into the maize genome. Artificial selection has affected thousands of targets, including genes and non-genic regions, leading to a reduction in nucleotide diversity and an increase in the proportion of rare alleles," the researchers write.
The first two reports, which were funded by the US Department of Agriculture, "represent a major step forward and an important tool in the arsenal available to scientists and breeders for improving a vital source of nutrition, as well as a source of fuel, in the face of changing climates, growing populations, and a diminishing supply of arable land," says Edward Knipling from the USDA's Agricultural Research Service.