Making the Most of Corn: The Identification and Characterization of Exotic Genes and Germplasm for Maize Improvement

Diversity is critical to any plant breeding program. Diversity allows for adaptation to future unknown challenges, such as climate change, abiotic and biotic stresses, market demands and consumer needs. This century will introduce novel challenges to crop production as the world's population is expected to exceed nine billion in the next 35 years. Along with growing pressures from higher demands in crop production, climate change has the potential to thwart any efforts by creating drastic changes in microenvironments. Therefore, it is increasingly important to incorporate and develop genetically diverse resources for plant breeders.;Genetic diversity can take many forms, and in this thesis, three categories will be explored. While all within maize's (Zea mays L. ssp. mays) primary gene pool, they are very different. In the first two chapters, the ancestor and wild relative, teosinte ( Zea mays ssp. parviglumis) was introgressed into a well-known and popular, temperate-adapted, maize inbred, B73, and screened for potential disease resistance alleles. In the third chapter, older elite inbreds, with expired plant variety protected certificates, were characterized for the presence of a crossing barrier gene, Gametophyte factor 1 . This gene was proposed for use in organic crop production to limit the amount of contamination from genetically modified organisms during pollination. The fourth chapter aims to describe the usefulness of semi-exotic germplasm through the identification of high yielding, agronomically viable, Germplasm Enhancement of Maize (GEM) lines, which were then inter-mated in an attempt to develop superior progeny, compared to their semi-exotic GEM parents and commercial hybrid checks.;Diversity explored in this thesis includes wild relatives, semi-exotic germplasm, and older elite inbreds. Each source is valuable and while different, serves to increase the diversity of any maize breeding program. The germplasm resources explored in these studies are publically available for immediate use through the Germplasm Recourses Information Network (GRIN) within the USDA-ARS-National Genetic Resources Program.