Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2017
Publication Date: 4/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5700681
Citation: Karn, A., Gillman, J.D., Flint Garcia, S.A. 2017. Genetic analysis of teosinte alleles for kernel composition traits in maize. G3, Genes/Genomes/Genetics. 7(4):1157-1164. doi:org/10.1534/g3.117.039529.
Interpretive Summary: Understanding the genetics of corn (maize) kernel composition is crucial for its use as food, feed, and fuel around the world. Maize was domesticated from its wild ancestor teosinte 9000 years ago in central Mexico, and has been subjected to modern plant breeding over the past 100 years. The domestication and breeding processes resulted in the transformation of a grassy weed into a high yielding commodity, but at the cost of genetic diversity underlying kernel size and composition traits. In order to understand the relationship between genetic diversity from teosinte and grain composition, we evaluated kernel starch, protein, and oil content in a maize population that contains small amounts of teosinte genome. We found that some of the regions of the genome that control grain composition in our population were previously known in maize, but we also found several new regions of the genome from teosinte that control grain composition. Ultimately, these novel regions of the teosinte genome can be mined for useful variation to improve corn for producers and consumers, as well as many industrial applications.
Technical Abstract: Teosinte (Zea mays ssp. parviglumis) is the wild ancestor of modern maize (Zea mays ssp. mays). Teosinte contains greater genetic diversity compared to maize inbreds and landraces, but its use is limited by insufficient genetic resources to evaluate its value. A population of teosinte near isogenic lines (teosinte NILs) was previously developed to broaden the resources for genetic diversity of maize, and to discover novel alleles for agronomic and domestication traits. The 961 teosinte NILs were developed by backcrossing ten geographically diverse parviglumis accessions into the B73 (reference genome inbred) background. The NILs were grown in two replications in 2009 and 2010 in Columbia, Missouri and Aurora, New York, respectively, and Near Infrared Reflectance (NIR) spectroscopy and Nuclear Magnetic Resonance (NMR) calibrations were developed and used to rapidly predict total kernel starch, protein and oil content on a dry matter basis in bulk whole grains of teosinte NILs. Our joint-linkage quantitative trait locus (QTL) mapping analysis identified two starch, three protein and six oil QTL, which collectively explained 18%, 23% and 45% of the total variation, respectively. A range of strong additive allelic effects for kernel starch, protein and oil content were identified relative to the B73 allele. Our results strongly support our hypothesis that teosinte harbors stronger alleles for kernel composition traits than maize, and can be exploited for the improvement of kernel composition traits in modern maize germplasm.