Maize and crop diversity is the product of millions of years of evolution. This evolution has resulted in numerous adaptations. Our group and collaborators have developed and/or characterized germplasm resources in order to powerfully analyze and use this diversity.
Maize NAM (Nested Association Mapping)
In collaboration with McMullen, Holland, Flint-Garcia, Kresovich labs, we developed the maize nested association design and mapping population. At the time it was created, it was the largest public sector tool for genetic mapping ever created for any species. While it only tapped the diversity of 25 founder lines, it was large enough to address questions on magnitudes of quantitative trait loci effects, heterosis, and the mapping of numerous genes controlling various traits.
Long-term the greatest value is a community resource that can be shared worldwide. Soon we will develop a page highlighting the dozen of papers on NAM.
Germplasm is available through the Maize Genetics Stock Center.
Key Papers: Design and structure, statistical considerations, genetic architecture
Data: Genotypes are phenotypes are available through Panzea.
Ames Inbred Lines
Breeders from around the world have developed lines that are specifically adapted to their environments. The USDA North Central Regional Plant Introduction Station in Ames, Iowas maintains over 3000 maize inbreds from around the world. Cinta Romay collaborated with Gardner and Millard to genotype and evaluate the germplasm for some key traits. In the initial study, Romay showed how powerfully this population was for association mapping. Over the coming years, our projects will be able to provide a nearly complete sequence for this tremendous germplasm resource.
Key Papers: Genotyping and flowering time, height.
Maize 282 Association Panel
Major Goodman has helped lead the maize community for decades on the importance of germplasm. In the late 1990s, when the technology to genotype was very limited, Goodman choose a panel of 282 breeding lines of maize from throughout the world. Almost 20 years later, we see that these were an excellent choice for a small association panel. They are biased to temperate lines, but do include tropical, sweet corns, and popcorns.
This panel has been used in numerous community diversity and mapping studies.
Key paper: Population and structure.
Data: Genotypic and phenotypic data in Panzea
By the end 2015, their entire genomes will be sequenced with the support of USDA-ARS.