Expanding maize genetic resources with predomestication alleles: maize-teosinte introgression populations

Authors: LIU, ZHENGBIN - University Of Missouri; COOK, JASON - University Of Missouri; Melia-Hancock, Susan; Guill, Katherine; BOTTOMS, CHRISTOPHER - University Of Missouri; Garcia, Arturo; OTT, OLIVER - Cornell University; NELSON, REBECCA - Cornell University; RECKER, JILL - North Carolina State University; Balint-Kurti, Peter; LARSSON, SARA - Cornell University; Lepak, Nicholas; Buckler, Edward - Ed; TRIMBLE, LOREN - University Of Wisconsin; TRACY, WILLIAM - University Of Wisconsin; McMullen, Michael; Flint-Garcia, Sherry

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2015
Publication Date: 3/4/2016
Publication URL: https://handle.nal.usda.gov/10113/62259
Citation: Liu, Z., Cook, J., Melia-Hancock, S., Guill, K.E., Bottoms, C., Garcia, A., Ott, O., Nelson, R., Recker, J., Balint-Kurti, P.J., Larsson, S., Lepak, N.K., Buckler, E.S., Trimble, L., Tracy, W., McMullen, M.D., Flint-Garcia, S.A. 2016. Expanding maize genetic resources with predomestication alleles: maize-teosinte introgression populations. The Plant Genome. 9(1). doi:10.3835/plantgenome2015.07.0053.

Interpretive Summary: During the domestication of corn (maize) from its wild ancestor (teosinte), humans selected plants that were more reliable, easier to harvest, and better tasting, thus causing dramatic transformations in plant, ear, and seed characteristics. However, domestication also greatly reduced genetic diversity in modern maize compared to teosinte, a reduction which may ultimately limit maize productivity. Because teosinte growth and morphology are so different than maize, it is nearly impossible to identify traits in teosinte that may be used for maize improvement. To overcome this limitation, we created by simple backcross breeding over 900 new lines of corn that carry small amounts of the teosinte DNA in their genome. We determined which chromosomal regions from teosinte are present in each line, and we evaluated these lines in field trials for plant, ear and kernel traits. We identified numerous chromosomal regions involved in the complex genetic network regulating several traits that contribute to yield. We also showed how this collection of lines can be used to validate and refine genetic studies, thus improving the process for gene discovery in maize. These lines will be used by breeders and geneticists in both the private and public sectors, in their efforts to understand the impact of domestication on modern maize, unravel the basis of important quantitative traits, and discover useful variation for maize improvement.

Technical Abstract: Teosinte (Zea mays ssp. parviglumis) has greater genetic diversity than maize inbreds and landraces (Z. mays ssp. mays). There are, however, limited genetic resources to efficiently evaluate and tap this diversity. To broaden resources for genetic diversity studies in maize, we developed and evaluated 928 near-isogenic introgression lines (NILs) from ten Z. mays ssp. parviglumis accessions in the B73 background. Joint linkage analysis of the ten introgression populations identified several large-effect quantitative trait loci (QTL) for days to anthesis (DTA), kernel row number (KRN), and 50-kernel weight (Wt50k). Our results both confirm prior reports of kernel domestication loci and identify previously uncharacterized QTLs with a range of allelic effects enabling future research into the genetic basis of these traits. Additionally, we used a targeted set of NILs to validate the effects of a KRN QTL located on chromosome two. These introgression populations offer novel tools for QTL discovery and validation, as well as a platform for initiating fine mapping.