Dosage dependent genes affecting seed composition and weight

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PI: A. Mark Settles (University of Florida)Collaborators: George Casella (University of Florida), L. Curtis Hannah (University of Florida), and Tamer Kahveci (University of Florida)Cereal yield and grain composition are two important targets for improving food security and reducing the environmental impact of agriculture. Cereals show genetic variation in the amount and quality of protein, oil, and starch within the kernel. Little is known about the molecular mechanisms that control seed weight and seed composition. The objective of this project is to identify novel genes that impact seed weight and seed composition in corn. The project will focus on genes with dosage effects on the kernel. Dosage-effect genes show stepwise changes as the number of normal alleles increases instead of the dominant-recessive relationship found for most genes. The project hypothesis is that these genes will identify key biological processes that are important in controlling seed composition or seed weight. The project will develop a novel single kernel analyzer that utilizes seed weights and near infrared reflectance spectroscopy to determine the composition of individual seeds. The kernel analyzer will then be used to screen for families of corn that segregate for differences in seed composition or weight. Families that show segregation ratios consistent with a dosage effect will be tested for heritability in multiple field environments. Finally a genomics approach will be used to identify the mutant genes responsible for the dosage effects. The research is expected to identify approximately ten to twenty genes that have seed dosage effects along with fifty seed mutants that show dosage sensitive phenotypes. These outcomes are significant, because they are expected to develop a novel understanding of the biological processes important for determining final seed composition and weight within cereals. This knowledge will provide a foundation to develop cereal crops with desired grain traits. Broader Impacts: The project will have broader impacts at four levels. (A) The research plan uses an interdisciplinary approach incorporating: plant genetics, molecular biology, analytical chemistry, engineering, statistics, and computer science to identify genes linked to quantitative kernel traits. These genes most likely will have significant impacts on cereal seed weight or cereal nutrient composition. Seed weight genes can be used to improve yield, while seed composition genes can be used to improve the nutritional value of human and animal diets. The project will generate quantitative trait data, flanking sequence tags for UniformMu lines, confirmed germinal transposon insertion sites, dosage-effect mutant stocks, and improvements on existing kernel analyzers. All quantitative kernel data will be available through a project website (to be developed) and through Gramene. Flanking sequence tags will be submitted to the GenBank GSS database and subsequent sequence analyses available at the UniformMu project website (http://currant.hos.ufl.edu/mutail/). (B) New tools for research will be developed. The grain analyzer can be used to determine composition of other grains and biological samples. Analyzer design will be freely available through the USDA Grain Marketing and Production Research Center (GMPRC) (www.gmprc.ksu.edu). (C) New biological resources will be developed. The project will identify and submit gene knockouts to the Maize Genetics Cooperative Stock Center for distribution to other researchers. (D) Post-doctoral, graduate, undergraduate, and high-school student training is an integrated part of the research plan. Importantly, the undergraduate researchers will be recruited through a collaboration with a Historically Black University, and the high school student training will target economically disadvantaged students.