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The origin of the naked grains of maize


The most critical step in maize (Zea mays ssp. mays) domestication was the liberation of the kernel from the hardened, protective casing that envelops the kernel in the maize progenitor, teosinte1. This evolutionary step exposed the kernel on the surface of the ear, such that it could readily be used by humans as a food source. Here we show that this key event in maize domestication is controlled by a single gene (teosinte glume architecture or tga1), belonging to the SBP-domain family2 of transcriptional regulators. The factor controlling the phenotypic difference between maize and teosinte maps to a 1-kilobase region, within which maize and teosinte show only seven fixed differences in their DNA sequences. One of these differences encodes a non-conservative amino acid substitution and may affect protein function, and the other six differences potentially affect gene regulation. Molecular evolution analyses show that this region was the target of selection during maize domestication. Our results demonstrate that modest genetic changes in single genes can induce dramatic changes in phenotype during domestication and evolution.

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Figure 1: Phenotypes.
Figure 2: The tga1 locus.
Figure 3: Molecular analysis of tga1.
Figure 4: Tissue in situ hybridizations.
Figure 5: Molecular evolution.

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We thank D. Baum and J. Wendel for comments, R. Clark for helpful discussions; E. Ananiev, K. Fengler and M. Morgante for help with screening and identifying BAC contigs; the DuPont sequencing group for BAC sequencing; and P. Rose for assistance with genetic mapping. This research was supported in part by grants from the National Institutes of Health and the USDA Hatch program (to J.F.D.), a Howard Hughes Medical Institute predoctoral fellowship (to K.B.), and an Environmental Protection Agency predoctoral fellowship (to L.L).

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Correspondence to John F. Doebley.

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All sequences have been deposited in GenBank under accession numbers AY883436–AY883568. Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Notes

Includes Supplementary Methods, Supplementary Results, Supplementary Tables S1-S3 and Supplementary Figures. (DOC 519 kb)

Supplementary Figure S1

An enlarged version of Figures 1f-h from the main text. (PDF 47 kb)

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Wang, H., Nussbaum-Wagler, T., Li, B. et al. The origin of the naked grains of maize. Nature 436, 714–719 (2005).

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