Functional Analysis of Selected Genes in Maize

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PI: John F. Doebley (University of Wisconsin - Madison)Collaborator: David M. Wills (University of Wisconsin - Madison)Crop plants are the products of selective breeding, a process whereby plant breeders select for gene variants that confer useful traits and against variants that confer detrimental traits. Generally, hundreds of genes have been the targets of selective breeding in a single crop species. Over the last decade, approximately 80 genes have been specifically identified as targets of breeding during the domestication and improvement of maize. It is not clear why variants of these maize genes were particularly favored by selective breeding, in part because it is not known what favorable traits are affected by the gene variants. Identifying the specific traits influenced by a gene variant is important to understanding how maize has been able to adapt so widely to diverse conditions across the globe. Further, this information increases the potential for further adaptive selection, a process likely needed in the future as climate change demands new growth strategies in crops. This project addresses the problem of identifying why and how variants have been selected in maize using three approaches. First, differences in gene expression, a form of gene activity, will be examined in selected and unselected variants for each of the 80 maize genes. The results will indicate whether selection favored variants with higher or lower levels of gene expression. Second, four of the selected maize genes will be analyzed in detail to determine which characteristics they control, focusing on agronomic traits related to yield, harvest and adaptation to the environment. Third, mutations in the four selected genes will be identified and the mutants studied genetically to understand gene function.These studies should provide genetic explanations for how maize has become one of the most productive agricultural crops worldwide. Understanding how genetic diversity generates agronomic diversity is necessary to improve the agricultural performance of maize in a changing world. Maize is also an excellent model crop for training students and future breeders in understanding the processes of evolution, genetics, and agriculture. Undergraduate students will be mentored in maize diversity research as part of the Integrated Biological Sciences Summer Research Program (IBS-SRP) at the University of Wisconsin. The IBS-SRP provides research opportunities for students from diverse backgrounds, thus providing an introduction to scientific research that may not be otherwise available. Data generated by the project will be available at the project website (www.panzea.org) and the Maize Genetics Database at www.maizegdb.org. All seed stocks developed by the project will be available via the Maize Genetics Cooperation Stock Center at http://maizecoop.cropsci.uiuc.edu.