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Title: Defining the role of the MADS-box gene, Zea agamous like1, in maize domestication

Author
item Wills, David
item FANG, ZHOU - North Carolina State University
item YORK, ALESSANDRA - University Of Wisconsin
item Holland, Jim - Jim
item DOEBLEY, JOHN - University Of Wisconsin

Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2017
Publication Date: 5/1/2018
Citation: Wills, D.M., Fang, Z., York, A., Holland, J.B., Doebley, J. 2018. Defining the role of the MADS-box gene, Zea agamous like1, in maize domestication. Journal of Heredity. 109:333-338.

Interpretive Summary: The ability to identify the genes which determine a desired phenotype would be of great value to plant breeders. As scientist’s ability to analyze genetic information rapidly continues to improve, one method used to identify important genes has been to look for loci that have been altered by selection over time. Whole genomes of populations of plants can be quickly scanned to find candidate genes that may have been selected during crop domestication and improvement. These scans often identify dozens, hundreds or even thousands of genes as candidates of selection. However, the scans do not identify the traits these genes control and follow up research is necessary to link these potentially important genes to those traits. In this study we determined a number of traits affected by an important candidate gene, zea agamous like1 (zagl1). This locus has been shown to be a selection candidate gene in multiple studies of genetic diversity in maize. We created a number of maize lines which carry the wild allele for zagl1 from maize’s progenitor, teosinte, and then compared them to lines which contained the selected maize allele. By measuring a number of important plant traits in maize we were able to show that the selected allele increased the size of the maize ear, increasing the potential quantity of grain. This work demonstrates that scans for selection can be used to uncover genes that control critical plant traits of interest to breeders.

Technical Abstract: Genomic scans for genes that show the signature of past selection have been widely applied to a number of species and have identified a large number of selection candidate genes. In cultivated maize (Zea mays ssp. mays) selection scans have identified several hundred candidate domestication genes by comparing nucleotide diversity and differentiation between maize and its progenitor, teosinte (Z. mays ssp. parviglumis). One of these is a gene called zea agamous-like1(zagl1), a MADS-box transcription factor, that is known for it that is known for its function in the control of flowering time. To determine the trait(s) controlled by zagl1 that was(were) the target(s) of selection during maize domestication, we created a set of recombinant chromosome isogenic lines that differ for the maize versus teosinte alleles of zagl1 and which carry cross-overs between zagl1 and its neighbor genes. These lines were grown in a randomized trial and scored for flowering time and domestication related traits. The results indicated that the maize versus teosinte alleles of zagl1 affect flowering time as expected and multiple traits related to ear size, with the maize allele conferring larger ears, with more kernels. Our results suggest that zagl1 may have been under selection during domestication to increase the size of the maize ear.