GENETIC MECHANISMS AND MOLECULAR GENETIC RESOURCES FOR MAIZE
Location: Plant Genetics Research
Title: Genetic architecture of maize kernel composition in the nested association mapping and inbred association panels
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 2011
Publication Date: February 1, 2012
Citation: Cook, J.P., McMullen, M.D., Holland, J.B., Tian, F., Bradbury, P., Ross-Ibarra, J., Buckler IV, E.S., Flint-Garcia, S.A. 2012. Genetic architecture of maize kernel composition in the nested association mapping and inbred association panels. Plant Physiology. 158:824-834.
Interpretive Summary: The composition of a maize (corn) kernel -- starch, protein, and oil -- is the determining factor for how the grain is utilized by an end user. Traditionally, maize has been an essential source of food, energy and nutrition to humans and livestock world-wide. Recently, maize has also become an important feedstock for ethanol production in the United States, and is used as a raw material for several industrial applications. An understanding of the genes regulating the production of kernel starch, protein, and oil in genetically diverse populations will provide valuable information on how kernel composition can be optimized to meet the needs of diverse end uses. We evaluated starch, protein, and oil in the genetically diverse nested association mapping (NAM) population and 282 inbred association panel. We identified numerous chromosomal regions involved in the complex genetic network regulating starch, protein, and oil content, and were able to refine one such chromosomal region to the gene level. We found that diverse maize lines contain combinations of these chromosome regions, and that no single line contained all the favorable variants for any one composition trait. Thus, lines with high starch, protein, or oil can be derived by combining favorable variants from different lines into a single line by breeding and/or transgenic approaches. These results can be used by corn breeders and geneticists to optimize kernel composition for specific end-use applications.
The maize kernel plays a critical role in feeding humans and livestock around the world and in a wide array of industrial applications. An understanding of the regulation of kernel starch, protein, and oil is needed in order to manipulate composition to meet future needs. We conducted quantitative trait locus (QTL) mapping and genome-wide association studies (GWAS) in the maize nested association mapping (NAM) population. Numerous associations were detected including several oil and starch associations in DGAT1-2, a gene which regulates oil composition and quantity. Results from NAM were verified in a 282 inbred association panel using both GWAS and candidate gene association approaches. Many beneficial alleles were identified for the improvement of kernel starch, protein, and oil content.